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Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86-64, vdso: Do not allocate memory for the vDSO
  clocksource: Change __ARCH_HAS_CLOCKSOURCE_DATA to a CONFIG option
  x86, vdso: Drop now wrong comment
  Document the vDSO and add a reference parser
  ia64: Replace clocksource.fsys_mmio with generic arch data
  x86-64: Move vread_tsc and vread_hpet into the vDSO
  clocksource: Replace vread with generic arch data
  x86-64: Add --no-undefined to vDSO build
  x86-64: Allow alternative patching in the vDSO
  x86: Make alternative instruction pointers relative
  x86-64: Improve vsyscall emulation CS and RIP handling
  x86-64: Emulate legacy vsyscalls
  x86-64: Fill unused parts of the vsyscall page with 0xcc
  x86-64: Remove vsyscall number 3 (venosys)
  x86-64: Map the HPET NX
  x86-64: Remove kernel.vsyscall64 sysctl
  x86-64: Give vvars their own page
  x86-64: Document some of entry_64.S
  x86-64: Fix alignment of jiffies variable
This commit is contained in:
Linus Torvalds 2011-07-22 17:05:15 -07:00
Родитель 3e0b8df79d aafade242f
Коммит 8e204874db
41 изменённых файлов: 946 добавлений и 397 удалений
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27
Documentation/ABI/stable/vdso Normal file
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@ -0,0 +1,27 @@
On some architectures, when the kernel loads any userspace program it
maps an ELF DSO into that program's address space. This DSO is called
the vDSO and it often contains useful and highly-optimized alternatives
to real syscalls.
These functions are called just like ordinary C function according to
your platform's ABI. Call them from a sensible context. (For example,
if you set CS on x86 to something strange, the vDSO functions are
within their rights to crash.) In addition, if you pass a bad
pointer to a vDSO function, you might get SIGSEGV instead of -EFAULT.
To find the DSO, parse the auxiliary vector passed to the program's
entry point. The AT_SYSINFO_EHDR entry will point to the vDSO.
The vDSO uses symbol versioning; whenever you request a symbol from the
vDSO, specify the version you are expecting.
Programs that dynamically link to glibc will use the vDSO automatically.
Otherwise, you can use the reference parser in Documentation/vDSO/parse_vdso.c.
Unless otherwise noted, the set of symbols with any given version and the
ABI of those symbols is considered stable. It may vary across architectures,
though.
(As of this writing, this ABI documentation as been confirmed for x86_64.
The maintainers of the other vDSO-using architectures should confirm
that it is correct for their architecture.)

256
Documentation/vDSO/parse_vdso.c Normal file
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/*
* parse_vdso.c: Linux reference vDSO parser
* Written by Andrew Lutomirski, 2011.
*
* This code is meant to be linked in to various programs that run on Linux.
* As such, it is available with as few restrictions as possible. This file
* is licensed under the Creative Commons Zero License, version 1.0,
* available at http://creativecommons.org/publicdomain/zero/1.0/legalcode
*
* The vDSO is a regular ELF DSO that the kernel maps into user space when
* it starts a program. It works equally well in statically and dynamically
* linked binaries.
*
* This code is tested on x86_64. In principle it should work on any 64-bit
* architecture that has a vDSO.
*/
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <elf.h>
/*
* To use this vDSO parser, first call one of the vdso_init_* functions.
* If you've already parsed auxv, then pass the value of AT_SYSINFO_EHDR
* to vdso_init_from_sysinfo_ehdr. Otherwise pass auxv to vdso_init_from_auxv.
* Then call vdso_sym for each symbol you want. For example, to look up
* gettimeofday on x86_64, use:
*
* <some pointer> = vdso_sym("LINUX_2.6", "gettimeofday");
* or
* <some pointer> = vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
*
* vdso_sym will return 0 if the symbol doesn't exist or if the init function
* failed or was not called. vdso_sym is a little slow, so its return value
* should be cached.
*
* vdso_sym is threadsafe; the init functions are not.
*
* These are the prototypes:
*/
extern void vdso_init_from_auxv(void *auxv);
extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
extern void *vdso_sym(const char *version, const char *name);
/* And here's the code. */
#ifndef __x86_64__
# error Not yet ported to non-x86_64 architectures
#endif
static struct vdso_info
{
bool valid;
/* Load information */
uintptr_t load_addr;
uintptr_t load_offset; /* load_addr - recorded vaddr */
/* Symbol table */
Elf64_Sym *symtab;
const char *symstrings;
Elf64_Word *bucket, *chain;
Elf64_Word nbucket, nchain;
/* Version table */
Elf64_Versym *versym;
Elf64_Verdef *verdef;
} vdso_info;
/* Straight from the ELF specification. */
static unsigned long elf_hash(const unsigned char *name)
{
unsigned long h = 0, g;
while (*name)
{
h = (h << 4) + *name++;
if (g = h & 0xf0000000)
h ^= g >> 24;
h &= ~g;
}
return h;
}
void vdso_init_from_sysinfo_ehdr(uintptr_t base)
{
size_t i;
bool found_vaddr = false;
vdso_info.valid = false;
vdso_info.load_addr = base;
Elf64_Ehdr *hdr = (Elf64_Ehdr*)base;
Elf64_Phdr *pt = (Elf64_Phdr*)(vdso_info.load_addr + hdr->e_phoff);
Elf64_Dyn *dyn = 0;
/*
* We need two things from the segment table: the load offset
* and the dynamic table.
*/
for (i = 0; i < hdr->e_phnum; i++)
{
if (pt[i].p_type == PT_LOAD && !found_vaddr) {
found_vaddr = true;
vdso_info.load_offset = base
+ (uintptr_t)pt[i].p_offset
- (uintptr_t)pt[i].p_vaddr;
} else if (pt[i].p_type == PT_DYNAMIC) {
dyn = (Elf64_Dyn*)(base + pt[i].p_offset);
}
}
if (!found_vaddr || !dyn)
return; /* Failed */
/*
* Fish out the useful bits of the dynamic table.
*/
Elf64_Word *hash = 0;
vdso_info.symstrings = 0;
vdso_info.symtab = 0;
vdso_info.versym = 0;
vdso_info.verdef = 0;
for (i = 0; dyn[i].d_tag != DT_NULL; i++) {
switch (dyn[i].d_tag) {
case DT_STRTAB:
vdso_info.symstrings = (const char *)
((uintptr_t)dyn[i].d_un.d_ptr
+ vdso_info.load_offset);
break;
case DT_SYMTAB:
vdso_info.symtab = (Elf64_Sym *)
((uintptr_t)dyn[i].d_un.d_ptr
+ vdso_info.load_offset);
break;
case DT_HASH:
hash = (Elf64_Word *)
((uintptr_t)dyn[i].d_un.d_ptr
+ vdso_info.load_offset);
break;
case DT_VERSYM:
vdso_info.versym = (Elf64_Versym *)
((uintptr_t)dyn[i].d_un.d_ptr
+ vdso_info.load_offset);
break;
case DT_VERDEF:
vdso_info.verdef = (Elf64_Verdef *)
((uintptr_t)dyn[i].d_un.d_ptr
+ vdso_info.load_offset);
break;
}
}
if (!vdso_info.symstrings || !vdso_info.symtab || !hash)
return; /* Failed */
if (!vdso_info.verdef)
vdso_info.versym = 0;
/* Parse the hash table header. */
vdso_info.nbucket = hash[0];
vdso_info.nchain = hash[1];
vdso_info.bucket = &hash[2];
vdso_info.chain = &hash[vdso_info.nbucket + 2];
/* That's all we need. */
vdso_info.valid = true;
}
static bool vdso_match_version(Elf64_Versym ver,
const char *name, Elf64_Word hash)
{
/*
* This is a helper function to check if the version indexed by
* ver matches name (which hashes to hash).
*
* The version definition table is a mess, and I don't know how
* to do this in better than linear time without allocating memory
* to build an index. I also don't know why the table has
* variable size entries in the first place.
*
* For added fun, I can't find a comprehensible specification of how
* to parse all the weird flags in the table.
*
* So I just parse the whole table every time.
*/
/* First step: find the version definition */
ver &= 0x7fff; /* Apparently bit 15 means "hidden" */
Elf64_Verdef *def = vdso_info.verdef;
while(true) {
if ((def->vd_flags & VER_FLG_BASE) == 0
&& (def->vd_ndx & 0x7fff) == ver)
break;
if (def->vd_next == 0)
return false; /* No definition. */
def = (Elf64_Verdef *)((char *)def + def->vd_next);
}
/* Now figure out whether it matches. */
Elf64_Verdaux *aux = (Elf64_Verdaux*)((char *)def + def->vd_aux);
return def->vd_hash == hash
&& !strcmp(name, vdso_info.symstrings + aux->vda_name);
}
void *vdso_sym(const char *version, const char *name)
{
unsigned long ver_hash;
if (!vdso_info.valid)
return 0;
ver_hash = elf_hash(version);
Elf64_Word chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) {
Elf64_Sym *sym = &vdso_info.symtab[chain];
/* Check for a defined global or weak function w/ right name. */
if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
ELF64_ST_BIND(sym->st_info) != STB_WEAK)
continue;
if (sym->st_shndx == SHN_UNDEF)
continue;
if (strcmp(name, vdso_info.symstrings + sym->st_name))
continue;
/* Check symbol version. */
if (vdso_info.versym
&& !vdso_match_version(vdso_info.versym[chain],
version, ver_hash))
continue;
return (void *)(vdso_info.load_offset + sym->st_value);
}
return 0;
}
void vdso_init_from_auxv(void *auxv)
{
Elf64_auxv_t *elf_auxv = auxv;
for (int i = 0; elf_auxv[i].a_type != AT_NULL; i++)
{
if (elf_auxv[i].a_type == AT_SYSINFO_EHDR) {
vdso_init_from_sysinfo_ehdr(elf_auxv[i].a_un.a_val);
return;
}
}
vdso_info.valid = false;
}

111
Documentation/vDSO/vdso_test.c Normal file
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@ -0,0 +1,111 @@
/*
* vdso_test.c: Sample code to test parse_vdso.c on x86_64
* Copyright (c) 2011 Andy Lutomirski
* Subject to the GNU General Public License, version 2
*
* You can amuse yourself by compiling with:
* gcc -std=gnu99 -nostdlib
* -Os -fno-asynchronous-unwind-tables -flto
* vdso_test.c parse_vdso.c -o vdso_test
* to generate a small binary with no dependencies at all.
*/
#include <sys/syscall.h>
#include <sys/time.h>
#include <unistd.h>
#include <stdint.h>
extern void *vdso_sym(const char *version, const char *name);
extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
extern void vdso_init_from_auxv(void *auxv);
/* We need a libc functions... */
int strcmp(const char *a, const char *b)
{
/* This implementation is buggy: it never returns -1. */
while (*a || *b) {
if (*a != *b)
return 1;
if (*a == 0 || *b == 0)
return 1;
a++;
b++;
}
return 0;
}
/* ...and two syscalls. This is x86_64-specific. */
static inline long linux_write(int fd, const void *data, size_t len)
{
long ret;
asm volatile ("syscall" : "=a" (ret) : "a" (__NR_write),
"D" (fd), "S" (data), "d" (len) :
"cc", "memory", "rcx",
"r8", "r9", "r10", "r11" );
return ret;
}
static inline void linux_exit(int code)
{
asm volatile ("syscall" : : "a" (__NR_exit), "D" (code));
}
void to_base10(char *lastdig, uint64_t n)
{
while (n) {
*lastdig = (n % 10) + '0';
n /= 10;
lastdig--;
}
}
__attribute__((externally_visible)) void c_main(void **stack)
{
/* Parse the stack */
long argc = (long)*stack;
stack += argc + 2;
/* Now we're pointing at the environment. Skip it. */
while(*stack)
stack++;
stack++;
/* Now we're pointing at auxv. Initialize the vDSO parser. */
vdso_init_from_auxv((void *)stack);
/* Find gettimeofday. */
typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
if (!gtod)
linux_exit(1);
struct timeval tv;
long ret = gtod(&tv, 0);
if (ret == 0) {
char buf[] = "The time is .000000\n";
to_base10(buf + 31, tv.tv_sec);
to_base10(buf + 38, tv.tv_usec);
linux_write(1, buf, sizeof(buf) - 1);
} else {
linux_exit(ret);
}
linux_exit(0);
}
/*
* This is the real entry point. It passes the initial stack into
* the C entry point.
*/
asm (
".text\n"
".global _start\n"
".type _start,@function\n"
"_start:\n\t"
"mov %rsp,%rdi\n\t"
"jmp c_main"
);

98
Documentation/x86/entry_64.txt Normal file
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@ -0,0 +1,98 @@
This file documents some of the kernel entries in
arch/x86/kernel/entry_64.S. A lot of this explanation is adapted from
an email from Ingo Molnar:
http://lkml.kernel.org/r/<20110529191055.GC9835%40elte.hu>
The x86 architecture has quite a few different ways to jump into
kernel code. Most of these entry points are registered in
arch/x86/kernel/traps.c and implemented in arch/x86/kernel/entry_64.S
and arch/x86/ia32/ia32entry.S.
The IDT vector assignments are listed in arch/x86/include/irq_vectors.h.
Some of these entries are:
- system_call: syscall instruction from 64-bit code.
- ia32_syscall: int 0x80 from 32-bit or 64-bit code; compat syscall
either way.
- ia32_syscall, ia32_sysenter: syscall and sysenter from 32-bit
code
- interrupt: An array of entries. Every IDT vector that doesn't
explicitly point somewhere else gets set to the corresponding
value in interrupts. These point to a whole array of
magically-generated functions that make their way to do_IRQ with
the interrupt number as a parameter.
- emulate_vsyscall: int 0xcc, a special non-ABI entry used by
vsyscall emulation.
- APIC interrupts: Various special-purpose interrupts for things
like TLB shootdown.
- Architecturally-defined exceptions like divide_error.
There are a few complexities here. The different x86-64 entries
have different calling conventions. The syscall and sysenter
instructions have their own peculiar calling conventions. Some of
the IDT entries push an error code onto the stack; others don't.
IDT entries using the IST alternative stack mechanism need their own
magic to get the stack frames right. (You can find some
documentation in the AMD APM, Volume 2, Chapter 8 and the Intel SDM,
Volume 3, Chapter 6.)
Dealing with the swapgs instruction is especially tricky. Swapgs
toggles whether gs is the kernel gs or the user gs. The swapgs
instruction is rather fragile: it must nest perfectly and only in
single depth, it should only be used if entering from user mode to
kernel mode and then when returning to user-space, and precisely
so. If we mess that up even slightly, we crash.
So when we have a secondary entry, already in kernel mode, we *must
not* use SWAPGS blindly - nor must we forget doing a SWAPGS when it's
not switched/swapped yet.
Now, there's a secondary complication: there's a cheap way to test
which mode the CPU is in and an expensive way.
The cheap way is to pick this info off the entry frame on the kernel
stack, from the CS of the ptregs area of the kernel stack:
xorl %ebx,%ebx
testl $3,CS+8(%rsp)
je error_kernelspace
SWAPGS
The expensive (paranoid) way is to read back the MSR_GS_BASE value
(which is what SWAPGS modifies):
movl $1,%ebx
movl $MSR_GS_BASE,%ecx
rdmsr
testl %edx,%edx
js 1f /* negative -> in kernel */
SWAPGS
xorl %ebx,%ebx
1: ret
and the whole paranoid non-paranoid macro complexity is about whether
to suffer that RDMSR cost.
If we are at an interrupt or user-trap/gate-alike boundary then we can
use the faster check: the stack will be a reliable indicator of
whether SWAPGS was already done: if we see that we are a secondary
entry interrupting kernel mode execution, then we know that the GS
base has already been switched. If it says that we interrupted
user-space execution then we must do the SWAPGS.
But if we are in an NMI/MCE/DEBUG/whatever super-atomic entry context,
which might have triggered right after a normal entry wrote CS to the
stack but before we executed SWAPGS, then the only safe way to check
for GS is the slower method: the RDMSR.
So we try only to mark those entry methods 'paranoid' that absolutely
need the more expensive check for the GS base - and we generate all
'normal' entry points with the regular (faster) entry macros.

3
arch/ia64/Kconfig
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@ -101,6 +101,9 @@ config GENERIC_IOMAP
bool
default y
config ARCH_CLOCKSOURCE_DATA
def_bool y
config SCHED_OMIT_FRAME_POINTER
bool
default y

10
arch/ia64/include/asm/clocksource.h Normal file
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@ -0,0 +1,10 @@
/* IA64-specific clocksource additions */
#ifndef _ASM_IA64_CLOCKSOURCE_H
#define _ASM_IA64_CLOCKSOURCE_H
struct arch_clocksource_data {
void *fsys_mmio; /* used by fsyscall asm code */
};
#endif /* _ASM_IA64_CLOCKSOURCE_H */

2
arch/ia64/kernel/cyclone.c
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@ -115,7 +115,7 @@ int __init init_cyclone_clock(void)
}
/* initialize last tick */
cyclone_mc = cyclone_timer;
clocksource_cyclone.fsys_mmio = cyclone_timer;
clocksource_cyclone.archdata.fsys_mmio = cyclone_timer;
clocksource_register_hz(&clocksource_cyclone, CYCLONE_TIMER_FREQ);
return 0;

2
arch/ia64/kernel/time.c
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@ -468,7 +468,7 @@ void update_vsyscall(struct timespec *wall, struct timespec *wtm,
fsyscall_gtod_data.clk_mask = c->mask;
fsyscall_gtod_data.clk_mult = mult;
fsyscall_gtod_data.clk_shift = c->shift;
fsyscall_gtod_data.clk_fsys_mmio = c->fsys_mmio;
fsyscall_gtod_data.clk_fsys_mmio = c->archdata.fsys_mmio;
fsyscall_gtod_data.clk_cycle_last = c->cycle_last;
/* copy kernel time structures */

2
arch/ia64/sn/kernel/sn2/timer.c
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@ -54,7 +54,7 @@ ia64_sn_udelay (unsigned long usecs)
void __init sn_timer_init(void)
{
clocksource_sn2.fsys_mmio = RTC_COUNTER_ADDR;
clocksource_sn2.archdata.fsys_mmio = RTC_COUNTER_ADDR;
clocksource_register_hz(&clocksource_sn2, sn_rtc_cycles_per_second);
ia64_udelay = &ia64_sn_udelay;

4
arch/x86/Kconfig
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@ -95,6 +95,10 @@ config CLOCKSOURCE_WATCHDOG
config GENERIC_CLOCKEVENTS
def_bool y
config ARCH_CLOCKSOURCE_DATA
def_bool y
depends on X86_64
config GENERIC_CLOCKEVENTS_BROADCAST
def_bool y
depends on X86_64 || (X86_32 && X86_LOCAL_APIC)

4
arch/x86/include/asm/alternative-asm.h
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@ -17,8 +17,8 @@
.macro altinstruction_entry orig alt feature orig_len alt_len
.align 8
.quad \orig
.quad \alt
.long \orig - .
.long \alt - .
.word \feature
.byte \orig_len
.byte \alt_len

8
arch/x86/include/asm/alternative.h
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@ -43,8 +43,8 @@
#endif
struct alt_instr {
u8 *instr; /* original instruction */
u8 *replacement;
s32 instr_offset; /* original instruction */
s32 repl_offset; /* offset to replacement instruction */
u16 cpuid; /* cpuid bit set for replacement */
u8 instrlen; /* length of original instruction */
u8 replacementlen; /* length of new instruction, <= instrlen */
@ -84,8 +84,8 @@ static inline int alternatives_text_reserved(void *start, void *end)
"661:\n\t" oldinstr "\n662:\n" \
".section .altinstructions,\"a\"\n" \
_ASM_ALIGN "\n" \
_ASM_PTR "661b\n" /* label */ \
_ASM_PTR "663f\n" /* new instruction */ \
" .long 661b - .\n" /* label */ \
" .long 663f - .\n" /* new instruction */ \
" .word " __stringify(feature) "\n" /* feature bit */ \
" .byte 662b-661b\n" /* sourcelen */ \
" .byte 664f-663f\n" /* replacementlen */ \

18
arch/x86/include/asm/clocksource.h Normal file
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@ -0,0 +1,18 @@
/* x86-specific clocksource additions */
#ifndef _ASM_X86_CLOCKSOURCE_H
#define _ASM_X86_CLOCKSOURCE_H
#ifdef CONFIG_X86_64
#define VCLOCK_NONE 0 /* No vDSO clock available. */
#define VCLOCK_TSC 1 /* vDSO should use vread_tsc. */
#define VCLOCK_HPET 2 /* vDSO should use vread_hpet. */
struct arch_clocksource_data {
int vclock_mode;
};
#endif /* CONFIG_X86_64 */
#endif /* _ASM_X86_CLOCKSOURCE_H */

8
arch/x86/include/asm/cpufeature.h
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@ -331,8 +331,8 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
"2:\n"
".section .altinstructions,\"a\"\n"
_ASM_ALIGN "\n"
_ASM_PTR "1b\n"
_ASM_PTR "0\n" /* no replacement */
" .long 1b - .\n"
" .long 0\n" /* no replacement */
" .word %P0\n" /* feature bit */
" .byte 2b - 1b\n" /* source len */
" .byte 0\n" /* replacement len */
@ -349,8 +349,8 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
"2:\n"
".section .altinstructions,\"a\"\n"
_ASM_ALIGN "\n"
_ASM_PTR "1b\n"
_ASM_PTR "3f\n"
" .long 1b - .\n"
" .long 3f - .\n"
" .word %P1\n" /* feature bit */
" .byte 2b - 1b\n" /* source len */
" .byte 4f - 3f\n" /* replacement len */

1
arch/x86/include/asm/fixmap.h
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@ -78,6 +78,7 @@ enum fixed_addresses {
VSYSCALL_LAST_PAGE,
VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE
+ ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
VVAR_PAGE,
VSYSCALL_HPET,
#endif
FIX_DBGP_BASE,

6
arch/x86/include/asm/irq_vectors.h
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@ -17,7 +17,8 @@
* Vectors 0 ... 31 : system traps and exceptions - hardcoded events
* Vectors 32 ... 127 : device interrupts
* Vector 128 : legacy int80 syscall interface
* Vectors 129 ... INVALIDATE_TLB_VECTOR_START-1 : device interrupts
* Vector 204 : legacy x86_64 vsyscall emulation
* Vectors 129 ... INVALIDATE_TLB_VECTOR_START-1 except 204 : device interrupts
* Vectors INVALIDATE_TLB_VECTOR_START ... 255 : special interrupts
*
* 64-bit x86 has per CPU IDT tables, 32-bit has one shared IDT table.
@ -50,6 +51,9 @@
#ifdef CONFIG_X86_32
# define SYSCALL_VECTOR 0x80
#endif
#ifdef CONFIG_X86_64
# define VSYSCALL_EMU_VECTOR 0xcc
#endif
/*
* Vectors 0x30-0x3f are used for ISA interrupts.

6
arch/x86/include/asm/pgtable_types.h
Просмотреть файл

@ -107,7 +107,8 @@
#define __PAGE_KERNEL_NOCACHE (__PAGE_KERNEL | _PAGE_PCD | _PAGE_PWT)
#define __PAGE_KERNEL_UC_MINUS (__PAGE_KERNEL | _PAGE_PCD)
#define __PAGE_KERNEL_VSYSCALL (__PAGE_KERNEL_RX | _PAGE_USER)
#define __PAGE_KERNEL_VSYSCALL_NOCACHE (__PAGE_KERNEL_VSYSCALL | _PAGE_PCD | _PAGE_PWT)
#define __PAGE_KERNEL_VVAR (__PAGE_KERNEL_RO | _PAGE_USER)
#define __PAGE_KERNEL_VVAR_NOCACHE (__PAGE_KERNEL_VVAR | _PAGE_PCD | _PAGE_PWT)
#define __PAGE_KERNEL_LARGE (__PAGE_KERNEL | _PAGE_PSE)
#define __PAGE_KERNEL_LARGE_NOCACHE (__PAGE_KERNEL | _PAGE_CACHE_UC | _PAGE_PSE)
#define __PAGE_KERNEL_LARGE_EXEC (__PAGE_KERNEL_EXEC | _PAGE_PSE)
@ -129,7 +130,8 @@
#define PAGE_KERNEL_LARGE_NOCACHE __pgprot(__PAGE_KERNEL_LARGE_NOCACHE)
#define PAGE_KERNEL_LARGE_EXEC __pgprot(__PAGE_KERNEL_LARGE_EXEC)
#define PAGE_KERNEL_VSYSCALL __pgprot(__PAGE_KERNEL_VSYSCALL)
#define PAGE_KERNEL_VSYSCALL_NOCACHE __pgprot(__PAGE_KERNEL_VSYSCALL_NOCACHE)
#define PAGE_KERNEL_VVAR __pgprot(__PAGE_KERNEL_VVAR)
#define PAGE_KERNEL_VVAR_NOCACHE __pgprot(__PAGE_KERNEL_VVAR_NOCACHE)
#define PAGE_KERNEL_IO __pgprot(__PAGE_KERNEL_IO)
#define PAGE_KERNEL_IO_NOCACHE __pgprot(__PAGE_KERNEL_IO_NOCACHE)

4
arch/x86/include/asm/traps.h
Просмотреть файл

@ -1,6 +1,8 @@
#ifndef _ASM_X86_TRAPS_H
#define _ASM_X86_TRAPS_H
#include <linux/kprobes.h>
#include <asm/debugreg.h>
#include <asm/siginfo.h> /* TRAP_TRACE, ... */
@ -38,6 +40,7 @@ asmlinkage void alignment_check(void);
asmlinkage void machine_check(void);
#endif /* CONFIG_X86_MCE */
asmlinkage void simd_coprocessor_error(void);
asmlinkage void emulate_vsyscall(void);
dotraplinkage void do_divide_error(struct pt_regs *, long);
dotraplinkage void do_debug(struct pt_regs *, long);
@ -64,6 +67,7 @@ dotraplinkage void do_alignment_check(struct pt_regs *, long);
dotraplinkage void do_machine_check(struct pt_regs *, long);
#endif
dotraplinkage void do_simd_coprocessor_error(struct pt_regs *, long);
dotraplinkage void do_emulate_vsyscall(struct pt_regs *, long);
#ifdef CONFIG_X86_32
dotraplinkage void do_iret_error(struct pt_regs *, long);
#endif

4
arch/x86/include/asm/tsc.h
Просмотреть файл

@ -51,10 +51,6 @@ extern int unsynchronized_tsc(void);
extern int check_tsc_unstable(void);
extern unsigned long native_calibrate_tsc(void);
#ifdef CONFIG_X86_64
extern cycles_t vread_tsc(void);
#endif
/*
* Boot-time check whether the TSCs are synchronized across
* all CPUs/cores:

3
arch/x86/include/asm/vgtod.h
Просмотреть файл

@ -11,10 +11,9 @@ struct vsyscall_gtod_data {
time_t wall_time_sec;
u32 wall_time_nsec;
int sysctl_enabled;
struct timezone sys_tz;
struct { /* extract of a clocksource struct */
cycle_t (*vread)(void);
int vclock_mode;
cycle_t cycle_last;
cycle_t mask;
u32 mult;

4
arch/x86/include/asm/vsyscall.h
Просмотреть файл

@ -16,10 +16,6 @@ enum vsyscall_num {
#ifdef __KERNEL__
#include <linux/seqlock.h>
/* Definitions for CONFIG_GENERIC_TIME definitions */
#define __vsyscall_fn \
__attribute__ ((unused, __section__(".vsyscall_fn"))) notrace
#define VGETCPU_RDTSCP 1
#define VGETCPU_LSL 2

24
arch/x86/include/asm/vvar.h
Просмотреть файл

@ -10,15 +10,14 @@
* In normal kernel code, they are used like any other variable.
* In user code, they are accessed through the VVAR macro.
*
* Each of these variables lives in the vsyscall page, and each
* one needs a unique offset within the little piece of the page
* reserved for vvars. Specify that offset in DECLARE_VVAR.
* (There are 896 bytes available. If you mess up, the linker will
* catch it.)
* These variables live in a page of kernel data that has an extra RO
* mapping for userspace. Each variable needs a unique offset within
* that page; specify that offset with the DECLARE_VVAR macro. (If
* you mess up, the linker will catch it.)
*/
/* Offset of vars within vsyscall page */
#define VSYSCALL_VARS_OFFSET (3072 + 128)
/* Base address of vvars. This is not ABI. */
#define VVAR_ADDRESS (-10*1024*1024 - 4096)
#if defined(__VVAR_KERNEL_LDS)
@ -26,17 +25,17 @@
* right place.
*/
#define DECLARE_VVAR(offset, type, name) \
EMIT_VVAR(name, VSYSCALL_VARS_OFFSET + offset)
EMIT_VVAR(name, offset)
#else
#define DECLARE_VVAR(offset, type, name) \
static type const * const vvaraddr_ ## name = \
(void *)(VSYSCALL_START + VSYSCALL_VARS_OFFSET + (offset));
(void *)(VVAR_ADDRESS + (offset));
#define DEFINE_VVAR(type, name) \
type __vvar_ ## name \
__attribute__((section(".vsyscall_var_" #name), aligned(16)))
type name \
__attribute__((section(".vvar_" #name), aligned(16)))
#define VVAR(name) (*vvaraddr_ ## name)
@ -45,8 +44,7 @@
/* DECLARE_VVAR(offset, type, name) */
DECLARE_VVAR(0, volatile unsigned long, jiffies)
DECLARE_VVAR(8, int, vgetcpu_mode)
DECLARE_VVAR(16, int, vgetcpu_mode)
DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data)
#undef DECLARE_VVAR
#undef VSYSCALL_VARS_OFFSET

8
arch/x86/kernel/Makefile
Просмотреть файл

@ -24,17 +24,12 @@ endif
nostackp := $(call cc-option, -fno-stack-protector)
CFLAGS_vsyscall_64.o := $(PROFILING) -g0 $(nostackp)
CFLAGS_hpet.o := $(nostackp)
CFLAGS_vread_tsc_64.o := $(nostackp)
CFLAGS_paravirt.o := $(nostackp)
GCOV_PROFILE_vsyscall_64.o := n
GCOV_PROFILE_hpet.o := n
GCOV_PROFILE_tsc.o := n
GCOV_PROFILE_vread_tsc_64.o := n
GCOV_PROFILE_paravirt.o := n
# vread_tsc_64 is hot and should be fully optimized:
CFLAGS_REMOVE_vread_tsc_64.o = -pg -fno-optimize-sibling-calls
obj-y := process_$(BITS).o signal.o entry_$(BITS).o
obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
obj-y += time.o ioport.o ldt.o dumpstack.o
@ -43,7 +38,8 @@ obj-$(CONFIG_IRQ_WORK) += irq_work.o
obj-y += probe_roms.o
obj-$(CONFIG_X86_32) += sys_i386_32.o i386_ksyms_32.o
obj-$(CONFIG_X86_64) += sys_x86_64.o x8664_ksyms_64.o
obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o vread_tsc_64.o
obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o
obj-$(CONFIG_X86_64) += vsyscall_emu_64.o
obj-y += bootflag.o e820.o
obj-y += pci-dma.o quirks.o topology.o kdebugfs.o
obj-y += alternative.o i8253.o pci-nommu.o hw_breakpoint.o

23
arch/x86/kernel/alternative.c
Просмотреть файл

@ -14,7 +14,6 @@
#include <asm/pgtable.h>
#include <asm/mce.h>
#include <asm/nmi.h>
#include <asm/vsyscall.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/io.h>
@ -250,7 +249,6 @@ static void __init_or_module add_nops(void *insns, unsigned int len)
extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
extern s32 __smp_locks[], __smp_locks_end[];
extern char __vsyscall_0;
void *text_poke_early(void *addr, const void *opcode, size_t len);
/* Replace instructions with better alternatives for this CPU type.
@ -263,6 +261,7 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
struct alt_instr *end)
{
struct alt_instr *a;
u8 *instr, *replacement;
u8 insnbuf[MAX_PATCH_LEN];
DPRINTK("%s: alt table %p -> %p\n", __func__, start, end);
@ -276,25 +275,23 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
* order.
*/
for (a = start; a < end; a++) {
u8 *instr = a->instr;
instr = (u8 *)&a->instr_offset + a->instr_offset;
replacement = (u8 *)&a->repl_offset + a->repl_offset;
BUG_ON(a->replacementlen > a->instrlen);
BUG_ON(a->instrlen > sizeof(insnbuf));
BUG_ON(a->cpuid >= NCAPINTS*32);
if (!boot_cpu_has(a->cpuid))
continue;
#ifdef CONFIG_X86_64
/* vsyscall code is not mapped yet. resolve it manually. */
if (instr >= (u8 *)VSYSCALL_START && instr < (u8*)VSYSCALL_END) {
instr = __va(instr - (u8*)VSYSCALL_START + (u8*)__pa_symbol(&__vsyscall_0));
DPRINTK("%s: vsyscall fixup: %p => %p\n",
__func__, a->instr, instr);
}
#endif
memcpy(insnbuf, a->replacement, a->replacementlen);
memcpy(insnbuf, replacement, a->replacementlen);
/* 0xe8 is a relative jump; fix the offset. */
if (*insnbuf == 0xe8 && a->replacementlen == 5)
*(s32 *)(insnbuf + 1) += a->replacement - a->instr;
*(s32 *)(insnbuf + 1) += replacement - instr;
add_nops(insnbuf + a->replacementlen,
a->instrlen - a->replacementlen);
text_poke_early(instr, insnbuf, a->instrlen);
}
}

4
arch/x86/kernel/entry_64.S
Просмотреть файл

@ -9,6 +9,8 @@
/*
* entry.S contains the system-call and fault low-level handling routines.
*
* Some of this is documented in Documentation/x86/entry_64.txt
*
* NOTE: This code handles signal-recognition, which happens every time
* after an interrupt and after each system call.
*
@ -1109,6 +1111,8 @@ zeroentry spurious_interrupt_bug do_spurious_interrupt_bug
zeroentry coprocessor_error do_coprocessor_error
errorentry alignment_check do_alignment_check
zeroentry simd_coprocessor_error do_simd_coprocessor_error
zeroentry emulate_vsyscall do_emulate_vsyscall
/* Reload gs selector with exception handling */
/* edi: new selector */

11
arch/x86/kernel/hpet.c
Просмотреть файл

@ -72,7 +72,7 @@ static inline void hpet_set_mapping(void)
{
hpet_virt_address = ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
#ifdef CONFIG_X86_64
__set_fixmap(VSYSCALL_HPET, hpet_address, PAGE_KERNEL_VSYSCALL_NOCACHE);
__set_fixmap(VSYSCALL_HPET, hpet_address, PAGE_KERNEL_VVAR_NOCACHE);
#endif
}
@ -739,13 +739,6 @@ static cycle_t read_hpet(struct clocksource *cs)
return (cycle_t)hpet_readl(HPET_COUNTER);
}
#ifdef CONFIG_X86_64
static cycle_t __vsyscall_fn vread_hpet(void)
{
return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
}
#endif
static struct clocksource clocksource_hpet = {
.name = "hpet",
.rating = 250,
@ -754,7 +747,7 @@ static struct clocksource clocksource_hpet = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.resume = hpet_resume_counter,
#ifdef CONFIG_X86_64
.vread = vread_hpet,
.archdata = { .vclock_mode = VCLOCK_HPET },
#endif
};

6
arch/x86/kernel/traps.c
Просмотреть файл

@ -872,6 +872,12 @@ void __init trap_init(void)
set_bit(SYSCALL_VECTOR, used_vectors);
#endif
#ifdef CONFIG_X86_64
BUG_ON(test_bit(VSYSCALL_EMU_VECTOR, used_vectors));
set_system_intr_gate(VSYSCALL_EMU_VECTOR, &emulate_vsyscall);
set_bit(VSYSCALL_EMU_VECTOR, used_vectors);
#endif
/*
* Should be a barrier for any external CPU state:
*/

2
arch/x86/kernel/tsc.c
Просмотреть файл

@ -777,7 +777,7 @@ static struct clocksource clocksource_tsc = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_MUST_VERIFY,
#ifdef CONFIG_X86_64
.vread = vread_tsc,
.archdata = { .vclock_mode = VCLOCK_TSC },
#endif
};

49
arch/x86/kernel/vmlinux.lds.S
Просмотреть файл

@ -161,50 +161,47 @@ SECTIONS
#define VVIRT_OFFSET (VSYSCALL_ADDR - __vsyscall_0)
#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)
#define EMIT_VVAR(x, offset) .vsyscall_var_ ## x \
ADDR(.vsyscall_0) + offset \
: AT(VLOAD(.vsyscall_var_ ## x)) { \
*(.vsyscall_var_ ## x) \
} \
x = VVIRT(.vsyscall_var_ ## x);
. = ALIGN(4096);
__vsyscall_0 = .;
. = VSYSCALL_ADDR;
.vsyscall_0 : AT(VLOAD(.vsyscall_0)) {
.vsyscall : AT(VLOAD(.vsyscall)) {
*(.vsyscall_0)
} :user
. = ALIGN(L1_CACHE_BYTES);
.vsyscall_fn : AT(VLOAD(.vsyscall_fn)) {
*(.vsyscall_fn)
}
.vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1)) {
. = 1024;
*(.vsyscall_1)
}
.vsyscall_2 ADDR(.vsyscall_0) + 2048: AT(VLOAD(.vsyscall_2)) {
. = 2048;
*(.vsyscall_2)
}
.vsyscall_3 ADDR(.vsyscall_0) + 3072: AT(VLOAD(.vsyscall_3)) {
*(.vsyscall_3)
}
#define __VVAR_KERNEL_LDS
#include <asm/vvar.h>
#undef __VVAR_KERNEL_LDS
. = __vsyscall_0 + PAGE_SIZE;
. = 4096; /* Pad the whole page. */
} :user =0xcc
. = ALIGN(__vsyscall_0 + PAGE_SIZE, PAGE_SIZE);
#undef VSYSCALL_ADDR
#undef VLOAD_OFFSET
#undef VLOAD
#undef VVIRT_OFFSET
#undef VVIRT
__vvar_page = .;
.vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
/* Place all vvars at the offsets in asm/vvar.h. */
#define EMIT_VVAR(name, offset) \
. = offset; \
*(.vvar_ ## name)
#define __VVAR_KERNEL_LDS
#include <asm/vvar.h>
#undef __VVAR_KERNEL_LDS
#undef EMIT_VVAR
} :data
. = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
#endif /* CONFIG_X86_64 */
/* Init code and data - will be freed after init */

36
arch/x86/kernel/vread_tsc_64.c
Просмотреть файл

@ -1,36 +0,0 @@
/* This code runs in userspace. */
#define DISABLE_BRANCH_PROFILING
#include <asm/vgtod.h>
notrace cycle_t __vsyscall_fn vread_tsc(void)
{
cycle_t ret;
u64 last;
/*
* Empirically, a fence (of type that depends on the CPU)
* before rdtsc is enough to ensure that rdtsc is ordered
* with respect to loads. The various CPU manuals are unclear
* as to whether rdtsc can be reordered with later loads,
* but no one has ever seen it happen.
*/
rdtsc_barrier();
ret = (cycle_t)vget_cycles();
last = VVAR(vsyscall_gtod_data).clock.cycle_last;
if (likely(ret >= last))
return ret;
/*
* GCC likes to generate cmov here, but this branch is extremely
* predictable (it's just a funciton of time and the likely is
* very likely) and there's a data dependence, so force GCC
* to generate a branch instead. I don't barrier() because
* we don't actually need a barrier, and if this function
* ever gets inlined it will generate worse code.
*/
asm volatile ("");
return last;
}

312
arch/x86/kernel/vsyscall_64.c
Просмотреть файл

@ -2,6 +2,8 @@
* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
* Copyright 2003 Andi Kleen, SuSE Labs.
*
* [ NOTE: this mechanism is now deprecated in favor of the vDSO. ]
*
* Thanks to hpa@transmeta.com for some useful hint.
* Special thanks to Ingo Molnar for his early experience with
* a different vsyscall implementation for Linux/IA32 and for the name.
@ -11,10 +13,9 @@
* vsyscalls. One vsyscall can reserve more than 1 slot to avoid
* jumping out of line if necessary. We cannot add more with this
* mechanism because older kernels won't return -ENOSYS.
* If we want more than four we need a vDSO.
*
* Note: the concept clashes with user mode linux. If you use UML and
* want per guest time just set the kernel.vsyscall64 sysctl to 0.
* Note: the concept clashes with user mode linux. UML users should
* use the vDSO.
*/
/* Disable profiling for userspace code: */
@ -32,9 +33,12 @@
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/notifier.h>
#include <linux/syscalls.h>
#include <linux/ratelimit.h>
#include <asm/vsyscall.h>
#include <asm/pgtable.h>
#include <asm/compat.h>
#include <asm/page.h>
#include <asm/unistd.h>
#include <asm/fixmap.h>
@ -44,16 +48,12 @@
#include <asm/desc.h>
#include <asm/topology.h>
#include <asm/vgtod.h>
#define __vsyscall(nr) \
__attribute__ ((unused, __section__(".vsyscall_" #nr))) notrace
#define __syscall_clobber "r11","cx","memory"
#include <asm/traps.h>
DEFINE_VVAR(int, vgetcpu_mode);
DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
{
.lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock),
.sysctl_enabled = 1,
};
void update_vsyscall_tz(void)
@ -72,8 +72,9 @@ void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
unsigned long flags;
write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags);
/* copy vsyscall data */
vsyscall_gtod_data.clock.vread = clock->vread;
vsyscall_gtod_data.clock.vclock_mode = clock->archdata.vclock_mode;
vsyscall_gtod_data.clock.cycle_last = clock->cycle_last;
vsyscall_gtod_data.clock.mask = clock->mask;
vsyscall_gtod_data.clock.mult = mult;
@ -82,169 +83,138 @@ void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec;
vsyscall_gtod_data.wall_to_monotonic = *wtm;
vsyscall_gtod_data.wall_time_coarse = __current_kernel_time();
write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);
}
/* RED-PEN may want to readd seq locking, but then the variable should be
* write-once.
*/
static __always_inline void do_get_tz(struct timezone * tz)
static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
const char *message)
{
*tz = VVAR(vsyscall_gtod_data).sys_tz;
}
static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
struct task_struct *tsk;
static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
{
int ret;
asm volatile("syscall"
: "=a" (ret)
: "0" (__NR_gettimeofday),"D" (tv),"S" (tz)
: __syscall_clobber );
return ret;
}
static __always_inline long time_syscall(long *t)
{
long secs;
asm volatile("syscall"
: "=a" (secs)
: "0" (__NR_time),"D" (t) : __syscall_clobber);
return secs;
}
static __always_inline void do_vgettimeofday(struct timeval * tv)
{
cycle_t now, base, mask, cycle_delta;
unsigned seq;
unsigned long mult, shift, nsec;
cycle_t (*vread)(void);
do {
seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
vread = VVAR(vsyscall_gtod_data).clock.vread;
if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled ||
!vread)) {
gettimeofday(tv,NULL);
if (!show_unhandled_signals || !__ratelimit(&rs))
return;
tsk = current;
printk("%s%s[%d] %s ip:%lx cs:%lx sp:%lx ax:%lx si:%lx di:%lx\n",
level, tsk->comm, task_pid_nr(tsk),
message, regs->ip - 2, regs->cs,
regs->sp, regs->ax, regs->si, regs->di);
}
static int addr_to_vsyscall_nr(unsigned long addr)
{
int nr;
if ((addr & ~0xC00UL) != VSYSCALL_START)
return -EINVAL;
nr = (addr & 0xC00UL) >> 10;
if (nr >= 3)
return -EINVAL;
return nr;
}
void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk;
unsigned long caller;
int vsyscall_nr;
long ret;
local_irq_enable();
/*
* Real 64-bit user mode code has cs == __USER_CS. Anything else
* is bogus.
*/
if (regs->cs != __USER_CS) {
/*
* If we trapped from kernel mode, we might as well OOPS now
* instead of returning to some random address and OOPSing
* then.
*/
BUG_ON(!user_mode(regs));
/* Compat mode and non-compat 32-bit CS should both segfault. */
warn_bad_vsyscall(KERN_WARNING, regs,
"illegal int 0xcc from 32-bit mode");
goto sigsegv;
}
now = vread();
base = VVAR(vsyscall_gtod_data).clock.cycle_last;
mask = VVAR(vsyscall_gtod_data).clock.mask;
mult = VVAR(vsyscall_gtod_data).clock.mult;
shift = VVAR(vsyscall_gtod_data).clock.shift;
tv->tv_sec = VVAR(vsyscall_gtod_data).wall_time_sec;
nsec = VVAR(vsyscall_gtod_data).wall_time_nsec;
} while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
/* calculate interval: */
cycle_delta = (now - base) & mask;
/* convert to nsecs: */
nsec += (cycle_delta * mult) >> shift;
while (nsec >= NSEC_PER_SEC) {
tv->tv_sec += 1;
nsec -= NSEC_PER_SEC;
/*
* x86-ism here: regs->ip points to the instruction after the int 0xcc,
* and int 0xcc is two bytes long.
*/
vsyscall_nr = addr_to_vsyscall_nr(regs->ip - 2);
if (vsyscall_nr < 0) {
warn_bad_vsyscall(KERN_WARNING, regs,
"illegal int 0xcc (exploit attempt?)");
goto sigsegv;
}
tv->tv_usec = nsec / NSEC_PER_USEC;
}
int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
{
if (tv)
do_vgettimeofday(tv);
if (tz)
do_get_tz(tz);
return 0;
}
/* This will break when the xtime seconds get inaccurate, but that is
* unlikely */
time_t __vsyscall(1) vtime(time_t *t)
{
unsigned seq;
time_t result;
if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled))
return time_syscall(t);
do {
seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
result = VVAR(vsyscall_gtod_data).wall_time_sec;
} while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
if (t)
*t = result;
return result;
}
/* Fast way to get current CPU and node.
This helps to do per node and per CPU caches in user space.
The result is not guaranteed without CPU affinity, but usually
works out because the scheduler tries to keep a thread on the same
CPU.
tcache must point to a two element sized long array.
All arguments can be NULL. */
long __vsyscall(2)
vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
{
unsigned int p;
unsigned long j = 0;
/* Fast cache - only recompute value once per jiffies and avoid
relatively costly rdtscp/cpuid otherwise.
This works because the scheduler usually keeps the process
on the same CPU and this syscall doesn't guarantee its
results anyways.
We do this here because otherwise user space would do it on
its own in a likely inferior way (no access to jiffies).
If you don't like it pass NULL. */
if (tcache && tcache->blob[0] == (j = VVAR(jiffies))) {
p = tcache->blob[1];
} else if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
/* Load per CPU data from RDTSCP */
native_read_tscp(&p);
} else {
/* Load per CPU data from GDT */
asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
if (get_user(caller, (unsigned long __user *)regs->sp) != 0) {
warn_bad_vsyscall(KERN_WARNING, regs, "int 0xcc with bad stack (exploit attempt?)");
goto sigsegv;
}
if (tcache) {
tcache->blob[0] = j;
tcache->blob[1] = p;
tsk = current;
if (seccomp_mode(&tsk->seccomp))
do_exit(SIGKILL);
switch (vsyscall_nr) {
case 0:
ret = sys_gettimeofday(
(struct timeval __user *)regs->di,
(struct timezone __user *)regs->si);
break;
case 1:
ret = sys_time((time_t __user *)regs->di);
break;
case 2:
ret = sys_getcpu((unsigned __user *)regs->di,
(unsigned __user *)regs->si,
0);
break;
}
if (cpu)
*cpu = p & 0xfff;
if (node)
*node = p >> 12;
return 0;
if (ret == -EFAULT) {
/*
* Bad news -- userspace fed a bad pointer to a vsyscall.
*
* With a real vsyscall, that would have caused SIGSEGV.
* To make writing reliable exploits using the emulated
* vsyscalls harder, generate SIGSEGV here as well.
*/
warn_bad_vsyscall(KERN_INFO, regs,
"vsyscall fault (exploit attempt?)");
goto sigsegv;
}
regs->ax = ret;
/* Emulate a ret instruction. */
regs->ip = caller;
regs->sp += 8;
local_irq_disable();
return;
sigsegv:
regs->ip -= 2; /* The faulting instruction should be the int 0xcc. */
force_sig(SIGSEGV, current);
local_irq_disable();
}
static long __vsyscall(3) venosys_1(void)
{
return -ENOSYS;
}
#ifdef CONFIG_SYSCTL
static ctl_table kernel_table2[] = {
{ .procname = "vsyscall64",
.data = &vsyscall_gtod_data.sysctl_enabled, .maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec },
{}
};
static ctl_table kernel_root_table2[] = {
{ .procname = "kernel", .mode = 0555,
.child = kernel_table2 },
{}
};
#endif
/* Assume __initcall executes before all user space. Hopefully kmod
doesn't violate that. We'll find out if it does. */
/*
* Assume __initcall executes before all user space. Hopefully kmod
* doesn't violate that. We'll find out if it does.
*/
static void __cpuinit vsyscall_set_cpu(int cpu)
{
unsigned long d;
@ -255,13 +225,15 @@ static void __cpuinit vsyscall_set_cpu(int cpu)
if (cpu_has(&cpu_data(cpu), X86_FEATURE_RDTSCP))
write_rdtscp_aux((node << 12) | cpu);
/* Store cpu number in limit so that it can be loaded quickly
in user space in vgetcpu.
12 bits for the CPU and 8 bits for the node. */
/*
* Store cpu number in limit so that it can be loaded quickly
* in user space in vgetcpu. (12 bits for the CPU and 8 bits for the node)
*/
d = 0x0f40000000000ULL;
d |= cpu;
d |= (node & 0xf) << 12;
d |= (node >> 4) << 48;
write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
}
@ -275,8 +247,10 @@ static int __cpuinit
cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg)
{
long cpu = (long)arg;
if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
smp_call_function_single(cpu, cpu_vsyscall_init, NULL, 1);
return NOTIFY_DONE;
}
@ -284,25 +258,23 @@ void __init map_vsyscall(void)
{
extern char __vsyscall_0;
unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
extern char __vvar_page;
unsigned long physaddr_vvar_page = __pa_symbol(&__vvar_page);
/* Note that VSYSCALL_MAPPED_PAGES must agree with the code below. */
__set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
__set_fixmap(VVAR_PAGE, physaddr_vvar_page, PAGE_KERNEL_VVAR);
BUILD_BUG_ON((unsigned long)__fix_to_virt(VVAR_PAGE) != (unsigned long)VVAR_ADDRESS);
}
static int __init vsyscall_init(void)
{
BUG_ON(((unsigned long) &vgettimeofday !=
VSYSCALL_ADDR(__NR_vgettimeofday)));
BUG_ON((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime));
BUG_ON((VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE)));
BUG_ON((unsigned long) &vgetcpu != VSYSCALL_ADDR(__NR_vgetcpu));
#ifdef CONFIG_SYSCTL
register_sysctl_table(kernel_root_table2);
#endif
BUG_ON(VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE));
on_each_cpu(cpu_vsyscall_init, NULL, 1);
/* notifier priority > KVM */
hotcpu_notifier(cpu_vsyscall_notifier, 30);
return 0;
}
__initcall(vsyscall_init);

27
arch/x86/kernel/vsyscall_emu_64.S Normal file
Просмотреть файл

@ -0,0 +1,27 @@
/*
* vsyscall_emu_64.S: Vsyscall emulation page
*
* Copyright (c) 2011 Andy Lutomirski
*
* Subject to the GNU General Public License, version 2
*/
#include <linux/linkage.h>
#include <asm/irq_vectors.h>
/* The unused parts of the page are filled with 0xcc by the linker script. */
.section .vsyscall_0, "a"
ENTRY(vsyscall_0)
int $VSYSCALL_EMU_VECTOR
END(vsyscall_0)
.section .vsyscall_1, "a"
ENTRY(vsyscall_1)
int $VSYSCALL_EMU_VECTOR
END(vsyscall_1)
.section .vsyscall_2, "a"
ENTRY(vsyscall_2)
int $VSYSCALL_EMU_VECTOR
END(vsyscall_2)

9
arch/x86/lib/copy_page_64.S
Просмотреть файл

@ -2,6 +2,7 @@
#include <linux/linkage.h>
#include <asm/dwarf2.h>
#include <asm/alternative-asm.h>
ALIGN
copy_page_c:
@ -110,10 +111,6 @@ ENDPROC(copy_page)
2:
.previous
.section .altinstructions,"a"
.align 8
.quad copy_page
.quad 1b
.word X86_FEATURE_REP_GOOD
.byte .Lcopy_page_end - copy_page
.byte 2b - 1b
altinstruction_entry copy_page, 1b, X86_FEATURE_REP_GOOD, \
.Lcopy_page_end-copy_page, 2b-1b
.previous

11
arch/x86/lib/memmove_64.S
Просмотреть файл

@ -9,6 +9,7 @@
#include <linux/linkage.h>
#include <asm/dwarf2.h>
#include <asm/cpufeature.h>
#include <asm/alternative-asm.h>
#undef memmove
@ -214,11 +215,9 @@ ENTRY(memmove)
.previous
.section .altinstructions,"a"
.align 8
.quad .Lmemmove_begin_forward
.quad .Lmemmove_begin_forward_efs
.word X86_FEATURE_ERMS
.byte .Lmemmove_end_forward-.Lmemmove_begin_forward
.byte .Lmemmove_end_forward_efs-.Lmemmove_begin_forward_efs
altinstruction_entry .Lmemmove_begin_forward, \
.Lmemmove_begin_forward_efs,X86_FEATURE_ERMS, \
.Lmemmove_end_forward-.Lmemmove_begin_forward, \
.Lmemmove_end_forward_efs-.Lmemmove_begin_forward_efs
.previous
ENDPROC(memmove)

1
arch/x86/vdso/Makefile
Просмотреть файл

@ -26,6 +26,7 @@ targets += vdso.so vdso.so.dbg vdso.lds $(vobjs-y)
export CPPFLAGS_vdso.lds += -P -C
VDSO_LDFLAGS_vdso.lds = -m64 -Wl,-soname=linux-vdso.so.1 \
-Wl,--no-undefined \
-Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
$(obj)/vdso.o: $(src)/vdso.S $(obj)/vdso.so

79
arch/x86/vdso/vclock_gettime.c
Просмотреть файл

@ -6,7 +6,6 @@
*
* The code should have no internal unresolved relocations.
* Check with readelf after changing.
* Also alternative() doesn't work.
*/
/* Disable profiling for userspace code: */
@ -17,6 +16,7 @@
#include <linux/time.h>
#include <linux/string.h>
#include <asm/vsyscall.h>
#include <asm/fixmap.h>
#include <asm/vgtod.h>
#include <asm/timex.h>
#include <asm/hpet.h>
@ -25,6 +25,43 @@
#define gtod (&VVAR(vsyscall_gtod_data))
notrace static cycle_t vread_tsc(void)
{
cycle_t ret;
u64 last;
/*
* Empirically, a fence (of type that depends on the CPU)
* before rdtsc is enough to ensure that rdtsc is ordered
* with respect to loads. The various CPU manuals are unclear
* as to whether rdtsc can be reordered with later loads,
* but no one has ever seen it happen.
*/
rdtsc_barrier();
ret = (cycle_t)vget_cycles();
last = VVAR(vsyscall_gtod_data).clock.cycle_last;
if (likely(ret >= last))
return ret;
/*
* GCC likes to generate cmov here, but this branch is extremely
* predictable (it's just a funciton of time and the likely is
* very likely) and there's a data dependence, so force GCC
* to generate a branch instead. I don't barrier() because
* we don't actually need a barrier, and if this function
* ever gets inlined it will generate worse code.
*/
asm volatile ("");
return last;
}
static notrace cycle_t vread_hpet(void)
{
return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
}
notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
{
long ret;
@ -36,9 +73,12 @@ notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
notrace static inline long vgetns(void)
{
long v;
cycles_t (*vread)(void);
vread = gtod->clock.vread;
v = (vread() - gtod->clock.cycle_last) & gtod->clock.mask;
cycles_t cycles;
if (gtod->clock.vclock_mode == VCLOCK_TSC)
cycles = vread_tsc();
else
cycles = vread_hpet();
v = (cycles - gtod->clock.cycle_last) & gtod->clock.mask;
return (v * gtod->clock.mult) >> gtod->clock.shift;
}
@ -116,14 +156,13 @@ notrace static noinline int do_monotonic_coarse(struct timespec *ts)
notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
{
if (likely(gtod->sysctl_enabled))
switch (clock) {
case CLOCK_REALTIME:
if (likely(gtod->clock.vread))
if (likely(gtod->clock.vclock_mode != VCLOCK_NONE))
return do_realtime(ts);
break;
case CLOCK_MONOTONIC:
if (likely(gtod->clock.vread))
if (likely(gtod->clock.vclock_mode != VCLOCK_NONE))
return do_monotonic(ts);
break;
case CLOCK_REALTIME_COARSE:
@ -131,6 +170,7 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
case CLOCK_MONOTONIC_COARSE:
return do_monotonic_coarse(ts);
}
return vdso_fallback_gettime(clock, ts);
}
int clock_gettime(clockid_t, struct timespec *)
@ -139,7 +179,7 @@ int clock_gettime(clockid_t, struct timespec *)
notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
{
long ret;
if (likely(gtod->sysctl_enabled && gtod->clock.vread)) {
if (likely(gtod->clock.vclock_mode != VCLOCK_NONE)) {
if (likely(tv != NULL)) {
BUILD_BUG_ON(offsetof(struct timeval, tv_usec) !=
offsetof(struct timespec, tv_nsec) ||
@ -161,27 +201,14 @@ notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
int gettimeofday(struct timeval *, struct timezone *)
__attribute__((weak, alias("__vdso_gettimeofday")));
/* This will break when the xtime seconds get inaccurate, but that is
* unlikely */
static __always_inline long time_syscall(long *t)
{
long secs;
asm volatile("syscall"
: "=a" (secs)
: "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
return secs;
}
/*
* This will break when the xtime seconds get inaccurate, but that is
* unlikely
*/
notrace time_t __vdso_time(time_t *t)
{
time_t result;
if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled))
return time_syscall(t);
/* This is atomic on x86_64 so we don't need any locks. */
result = ACCESS_ONCE(VVAR(vsyscall_gtod_data).wall_time_sec);
time_t result = ACCESS_ONCE(VVAR(vsyscall_gtod_data).wall_time_sec);
if (t)
*t = result;

15
arch/x86/vdso/vdso.S
Просмотреть файл

@ -1,10 +1,21 @@
#include <asm/page_types.h>
#include <linux/linkage.h>
#include <linux/init.h>
__INITDATA
__PAGE_ALIGNED_DATA
.globl vdso_start, vdso_end
.align PAGE_SIZE
vdso_start:
.incbin "arch/x86/vdso/vdso.so"
vdso_end:
__FINIT
.previous
.globl vdso_pages
.bss
.align 8
.type vdso_pages, @object
vdso_pages:
.zero (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE * 8
.size vdso_pages, .-vdso_pages

58
arch/x86/vdso/vma.c
Просмотреть файл

@ -14,41 +14,61 @@
#include <asm/vgtod.h>
#include <asm/proto.h>
#include <asm/vdso.h>
#include <asm/page.h>
unsigned int __read_mostly vdso_enabled = 1;
extern char vdso_start[], vdso_end[];
extern unsigned short vdso_sync_cpuid;
static struct page **vdso_pages;
extern struct page *vdso_pages[];
static unsigned vdso_size;
static int __init init_vdso_vars(void)
static void __init patch_vdso(void *vdso, size_t len)
{
Elf64_Ehdr *hdr = vdso;
Elf64_Shdr *sechdrs, *alt_sec = 0;
char *secstrings;
void *alt_data;
int i;
BUG_ON(len < sizeof(Elf64_Ehdr));
BUG_ON(memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0);
sechdrs = (void *)hdr + hdr->e_shoff;
secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
for (i = 1; i < hdr->e_shnum; i++) {
Elf64_Shdr *shdr = &sechdrs[i];
if (!strcmp(secstrings + shdr->sh_name, ".altinstructions")) {
alt_sec = shdr;
goto found;
}
}
/* If we get here, it's probably a bug. */
pr_warning("patch_vdso: .altinstructions not found\n");
return; /* nothing to patch */
found:
alt_data = (void *)hdr + alt_sec->sh_offset;
apply_alternatives(alt_data, alt_data + alt_sec->sh_size);
}
static int __init init_vdso(void)
{
int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE;
int i;
patch_vdso(vdso_start, vdso_end - vdso_start);
vdso_size = npages << PAGE_SHIFT;
vdso_pages = kmalloc(sizeof(struct page *) * npages, GFP_KERNEL);
if (!vdso_pages)
goto oom;
for (i = 0; i < npages; i++) {
struct page *p;
p = alloc_page(GFP_KERNEL);
if (!p)
goto oom;
vdso_pages[i] = p;
copy_page(page_address(p), vdso_start + i*PAGE_SIZE);
}
for (i = 0; i < npages; i++)
vdso_pages[i] = virt_to_page(vdso_start + i*PAGE_SIZE);
return 0;
oom:
printk("Cannot allocate vdso\n");
vdso_enabled = 0;
return -ENOMEM;
}
subsys_initcall(init_vdso_vars);
subsys_initcall(init_vdso);
struct linux_binprm;

2
drivers/char/hpet.c
Просмотреть файл

@ -952,7 +952,7 @@ int hpet_alloc(struct hpet_data *hdp)
#ifdef CONFIG_IA64
if (!hpet_clocksource) {
hpet_mctr = (void __iomem *)&hpetp->hp_hpet->hpet_mc;
CLKSRC_FSYS_MMIO_SET(clocksource_hpet.fsys_mmio, hpet_mctr);
clocksource_hpet.archdata.fsys_mmio = hpet_mctr;
clocksource_register_hz(&clocksource_hpet, hpetp->hp_tick_freq);
hpetp->hp_clocksource = &clocksource_hpet;
hpet_clocksource = &clocksource_hpet;

15
include/linux/clocksource.h
Просмотреть файл

@ -22,6 +22,10 @@
typedef u64 cycle_t;
struct clocksource;
#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
#include <asm/clocksource.h>
#endif
/**
* struct cyclecounter - hardware abstraction for a free running counter
* Provides completely state-free accessors to the underlying hardware.
@ -153,7 +157,7 @@ extern u64 timecounter_cyc2time(struct timecounter *tc,
* @shift: cycle to nanosecond divisor (power of two)
* @max_idle_ns: max idle time permitted by the clocksource (nsecs)
* @flags: flags describing special properties
* @vread: vsyscall based read
* @archdata: arch-specific data
* @suspend: suspend function for the clocksource, if necessary
* @resume: resume function for the clocksource, if necessary
*/
@ -169,16 +173,13 @@ struct clocksource {
u32 shift;
u64 max_idle_ns;
#ifdef CONFIG_IA64
void *fsys_mmio; /* used by fsyscall asm code */
#define CLKSRC_FSYS_MMIO_SET(mmio, addr) ((mmio) = (addr))
#else
#define CLKSRC_FSYS_MMIO_SET(mmio, addr) do { } while (0)
#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
struct arch_clocksource_data archdata;
#endif
const char *name;
struct list_head list;
int rating;
cycle_t (*vread)(void);
int (*enable)(struct clocksource *cs);
void (*disable)(struct clocksource *cs);
unsigned long flags;

10
include/linux/seccomp.h
Просмотреть файл

@ -19,6 +19,11 @@ static inline void secure_computing(int this_syscall)
extern long prctl_get_seccomp(void);
extern long prctl_set_seccomp(unsigned long);
static inline int seccomp_mode(seccomp_t *s)
{
return s->mode;
}
#else /* CONFIG_SECCOMP */
#include <linux/errno.h>
@ -37,6 +42,11 @@ static inline long prctl_set_seccomp(unsigned long arg2)
return -EINVAL;
}
static inline int seccomp_mode(seccomp_t *s)
{
return 0;
}
#endif /* CONFIG_SECCOMP */
#endif /* _LINUX_SECCOMP_H */