In preparation for removing HANDLE_DOMAIN_IRQ_IRQENTRY, have arch/arm
perform all the irqentry accounting in its entry code.
For configurations with CONFIG_GENERIC_IRQ_MULTI_HANDLER, we can use
generic_handle_arch_irq(). Other than asm_do_IRQ(), all C calls to
handle_IRQ() are from irqchip handlers which will be called from
generic_handle_arch_irq(), so to avoid double accounting IRQ entry, the
entry logic is moved from handle_IRQ() into asm_do_IRQ().
For ARMv7M the entry assembly is tightly coupled with the NVIC irqchip, and
while the entry code should logically live under arch/arm/, moving the
entry logic there makes things more convoluted. So for now, place the
entry logic in the NVIC irqchip, but separated into a separate
function to make the split of responsibility clear.
For all other configurations without CONFIG_GENERIC_IRQ_MULTI_HANDLER,
IRQ entry is already handled in arch code, and requires no changes.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Now that we no longer rely on thread_info living at the base of the task
stack to be able to access the 'current' pointer, we can wire up the
generic support for moving thread_info into the task struct itself.
Note that this requires us to update the cpu field in thread_info
explicitly, now that the core code no longer does so. Ideally, we would
switch the percpu code to access the cpu field in task_struct instead,
but this unleashes #include circular dependency hell.
Co-developed-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Now that the user space TLS register is assigned on every return to user
space, we can use it to keep the 'current' pointer while running in the
kernel. This removes the need to access it via thread_info, which is
located at the base of the stack, but will be moved out of there in a
subsequent patch.
Use the __builtin_thread_pointer() helper when available - this will
help GCC understand that reloading the value within the same function is
not necessary, even when using the per-task stack protector (which also
generates accesses via the TLS register). For example, the generated
code below loads TPIDRURO only once, and uses it to access both the
stack canary and the preempt_count fields.
<do_one_initcall>:
e92d 41f0 stmdb sp!, {r4, r5, r6, r7, r8, lr}
ee1d 4f70 mrc 15, 0, r4, cr13, cr0, {3}
4606 mov r6, r0
b094 sub sp, #80 ; 0x50
f8d4 34e8 ldr.w r3, [r4, #1256] ; 0x4e8 <- stack canary
9313 str r3, [sp, #76] ; 0x4c
f8d4 8004 ldr.w r8, [r4, #4] <- preempt count
Co-developed-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
The MaverickCrunch support for ep93xx never made it into glibc and
was removed from gcc in its 4.8 release in 2012. It is now one of
the last parts of arch/arm/ that fails to build with the clang
integrated assembler, which is unlikely to ever want to support it.
The two alternatives are to force the use of binutils/gas when
building the crunch support, or to remove it entirely.
According to Hartley Sweeten:
"Martin Guy did a lot of work trying to get the maverick crunch working
but I was never able to successfully use it for anything. It "kind"
of works but depending on the EP93xx silicon revision there are still
a number of hardware bugs that either give imprecise or garbage results.
I have no problem with removing the kernel support for the maverick
crunch."
Unless someone else comes up with a good reason to keep it around,
remove it now. This touches mostly the ep93xx platform, but removes
a bit of code from ARM common ptrace and signal frame handling as well.
If there are remaining users of MaverickCrunch, they can use LTS
kernels for at least another five years before kernel support ends.
Link: https://lore.kernel.org/linux-arm-kernel/20210802141245.1146772-1-arnd@kernel.org/
Link: https://lore.kernel.org/linux-arm-kernel/20210226164345.3889993-1-arnd@kernel.org/
Link: https://github.com/ClangBuiltLinux/linux/issues/1272
Link: https://gcc.gnu.org/legacy-ml/gcc/2008-03/msg01063.html
Cc: "Martin Guy" <martinwguy@martinwguy@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
There are a couple of problems with the exception entry code that deals
with FP exceptions (which are reported as UND exceptions) when building
the kernel in Thumb2 mode:
- the conditional branch to vfp_kmode_exception in vfp_support_entry()
may be out of range for its target, depending on how the linker decides
to arrange the sections;
- when the UND exception is taken in kernel mode, the emulation handling
logic is entered via the 'call_fpe' label, which means we end up using
the wrong value/mask pairs to match and detect the NEON opcodes.
Since UND exceptions in kernel mode are unlikely to occur on a hot path
(as opposed to the user mode version which is invoked for VFP support
code and lazy restore), we can use the existing undef hook machinery for
any kernel mode instruction emulation that is needed, including calling
the existing vfp_kmode_exception() routine for unexpected cases. So drop
the call to call_fpe, and instead, install an undef hook that will get
called for NEON and VFP instructions that trigger an UND exception in
kernel mode.
While at it, make sure that the PC correction is accurate for the
execution mode where the exception was taken, by checking the PSR
Thumb bit.
Cc: Dmitry Osipenko <digetx@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Fixes: eff8728fe6 ("vmlinux.lds.h: Add PGO and AutoFDO input sections")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Define KASAN_SHADOW_OFFSET,KASAN_SHADOW_START and KASAN_SHADOW_END for
the Arm kernel address sanitizer. We are "stealing" lowmem (the 4GB
addressable by a 32bit architecture) out of the virtual address
space to use as shadow memory for KASan as follows:
+----+ 0xffffffff
| |
| | |-> Static kernel image (vmlinux) BSS and page table
| |/
+----+ PAGE_OFFSET
| |
| | |-> Loadable kernel modules virtual address space area
| |/
+----+ MODULES_VADDR = KASAN_SHADOW_END
| |
| | |-> The shadow area of kernel virtual address.
| |/
+----+-> TASK_SIZE (start of kernel space) = KASAN_SHADOW_START the
| | shadow address of MODULES_VADDR
| | |
| | |
| | |-> The user space area in lowmem. The kernel address
| | | sanitizer do not use this space, nor does it map it.
| | |
| | |
| | |
| | |
| |/
------ 0
0 .. TASK_SIZE is the memory that can be used by shared
userspace/kernelspace. It us used for userspace processes and for
passing parameters and memory buffers in system calls etc. We do not
need to shadow this area.
KASAN_SHADOW_START:
This value begins with the MODULE_VADDR's shadow address. It is the
start of kernel virtual space. Since we have modules to load, we need
to cover also that area with shadow memory so we can find memory
bugs in modules.
KASAN_SHADOW_END
This value is the 0x100000000's shadow address: the mapping that would
be after the end of the kernel memory at 0xffffffff. It is the end of
kernel address sanitizer shadow area. It is also the start of the
module area.
KASAN_SHADOW_OFFSET:
This value is used to map an address to the corresponding shadow
address by the following formula:
shadow_addr = (address >> 3) + KASAN_SHADOW_OFFSET;
As you would expect, >> 3 is equal to dividing by 8, meaning each
byte in the shadow memory covers 8 bytes of kernel memory, so one
bit shadow memory per byte of kernel memory is used.
The KASAN_SHADOW_OFFSET is provided in a Kconfig option depending
on the VMSPLIT layout of the system: the kernel and userspace can
split up lowmem in different ways according to needs, so we calculate
the shadow offset depending on this.
When kasan is enabled, the definition of TASK_SIZE is not an 8-bit
rotated constant, so we need to modify the TASK_SIZE access code in the
*.s file.
The kernel and modules may use different amounts of memory,
according to the VMSPLIT configuration, which in turn
determines the PAGE_OFFSET.
We use the following KASAN_SHADOW_OFFSETs depending on how the
virtual memory is split up:
- 0x1f000000 if we have 1G userspace / 3G kernelspace split:
- The kernel address space is 3G (0xc0000000)
- PAGE_OFFSET is then set to 0x40000000 so the kernel static
image (vmlinux) uses addresses 0x40000000 .. 0xffffffff
- On top of that we have the MODULES_VADDR which under
the worst case (using ARM instructions) is
PAGE_OFFSET - 16M (0x01000000) = 0x3f000000
so the modules use addresses 0x3f000000 .. 0x3fffffff
- So the addresses 0x3f000000 .. 0xffffffff need to be
covered with shadow memory. That is 0xc1000000 bytes
of memory.
- 1/8 of that is needed for its shadow memory, so
0x18200000 bytes of shadow memory is needed. We
"steal" that from the remaining lowmem.
- The KASAN_SHADOW_START becomes 0x26e00000, to
KASAN_SHADOW_END at 0x3effffff.
- Now we can calculate the KASAN_SHADOW_OFFSET for any
kernel address as 0x3f000000 needs to map to the first
byte of shadow memory and 0xffffffff needs to map to
the last byte of shadow memory. Since:
SHADOW_ADDR = (address >> 3) + KASAN_SHADOW_OFFSET
0x26e00000 = (0x3f000000 >> 3) + KASAN_SHADOW_OFFSET
KASAN_SHADOW_OFFSET = 0x26e00000 - (0x3f000000 >> 3)
KASAN_SHADOW_OFFSET = 0x26e00000 - 0x07e00000
KASAN_SHADOW_OFFSET = 0x1f000000
- 0x5f000000 if we have 2G userspace / 2G kernelspace split:
- The kernel space is 2G (0x80000000)
- PAGE_OFFSET is set to 0x80000000 so the kernel static
image uses 0x80000000 .. 0xffffffff.
- On top of that we have the MODULES_VADDR which under
the worst case (using ARM instructions) is
PAGE_OFFSET - 16M (0x01000000) = 0x7f000000
so the modules use addresses 0x7f000000 .. 0x7fffffff
- So the addresses 0x7f000000 .. 0xffffffff need to be
covered with shadow memory. That is 0x81000000 bytes
of memory.
- 1/8 of that is needed for its shadow memory, so
0x10200000 bytes of shadow memory is needed. We
"steal" that from the remaining lowmem.
- The KASAN_SHADOW_START becomes 0x6ee00000, to
KASAN_SHADOW_END at 0x7effffff.
- Now we can calculate the KASAN_SHADOW_OFFSET for any
kernel address as 0x7f000000 needs to map to the first
byte of shadow memory and 0xffffffff needs to map to
the last byte of shadow memory. Since:
SHADOW_ADDR = (address >> 3) + KASAN_SHADOW_OFFSET
0x6ee00000 = (0x7f000000 >> 3) + KASAN_SHADOW_OFFSET
KASAN_SHADOW_OFFSET = 0x6ee00000 - (0x7f000000 >> 3)
KASAN_SHADOW_OFFSET = 0x6ee00000 - 0x0fe00000
KASAN_SHADOW_OFFSET = 0x5f000000
- 0x9f000000 if we have 3G userspace / 1G kernelspace split,
and this is the default split for ARM:
- The kernel address space is 1GB (0x40000000)
- PAGE_OFFSET is set to 0xc0000000 so the kernel static
image uses 0xc0000000 .. 0xffffffff.
- On top of that we have the MODULES_VADDR which under
the worst case (using ARM instructions) is
PAGE_OFFSET - 16M (0x01000000) = 0xbf000000
so the modules use addresses 0xbf000000 .. 0xbfffffff
- So the addresses 0xbf000000 .. 0xffffffff need to be
covered with shadow memory. That is 0x41000000 bytes
of memory.
- 1/8 of that is needed for its shadow memory, so
0x08200000 bytes of shadow memory is needed. We
"steal" that from the remaining lowmem.
- The KASAN_SHADOW_START becomes 0xb6e00000, to
KASAN_SHADOW_END at 0xbfffffff.
- Now we can calculate the KASAN_SHADOW_OFFSET for any
kernel address as 0xbf000000 needs to map to the first
byte of shadow memory and 0xffffffff needs to map to
the last byte of shadow memory. Since:
SHADOW_ADDR = (address >> 3) + KASAN_SHADOW_OFFSET
0xb6e00000 = (0xbf000000 >> 3) + KASAN_SHADOW_OFFSET
KASAN_SHADOW_OFFSET = 0xb6e00000 - (0xbf000000 >> 3)
KASAN_SHADOW_OFFSET = 0xb6e00000 - 0x17e00000
KASAN_SHADOW_OFFSET = 0x9f000000
- 0x8f000000 if we have 3G userspace / 1G kernelspace with
full 1 GB low memory (VMSPLIT_3G_OPT):
- The kernel address space is 1GB (0x40000000)
- PAGE_OFFSET is set to 0xb0000000 so the kernel static
image uses 0xb0000000 .. 0xffffffff.
- On top of that we have the MODULES_VADDR which under
the worst case (using ARM instructions) is
PAGE_OFFSET - 16M (0x01000000) = 0xaf000000
so the modules use addresses 0xaf000000 .. 0xaffffff
- So the addresses 0xaf000000 .. 0xffffffff need to be
covered with shadow memory. That is 0x51000000 bytes
of memory.
- 1/8 of that is needed for its shadow memory, so
0x0a200000 bytes of shadow memory is needed. We
"steal" that from the remaining lowmem.
- The KASAN_SHADOW_START becomes 0xa4e00000, to
KASAN_SHADOW_END at 0xaeffffff.
- Now we can calculate the KASAN_SHADOW_OFFSET for any
kernel address as 0xaf000000 needs to map to the first
byte of shadow memory and 0xffffffff needs to map to
the last byte of shadow memory. Since:
SHADOW_ADDR = (address >> 3) + KASAN_SHADOW_OFFSET
0xa4e00000 = (0xaf000000 >> 3) + KASAN_SHADOW_OFFSET
KASAN_SHADOW_OFFSET = 0xa4e00000 - (0xaf000000 >> 3)
KASAN_SHADOW_OFFSET = 0xa4e00000 - 0x15e00000
KASAN_SHADOW_OFFSET = 0x8f000000
- The default value of 0xffffffff for KASAN_SHADOW_OFFSET
is an error value. We should always match one of the
above shadow offsets.
When we do this, TASK_SIZE will sometimes get a bit odd values
that will not fit into immediate mov assembly instructions.
To account for this, we need to rewrite some assembly using
TASK_SIZE like this:
- mov r1, #TASK_SIZE
+ ldr r1, =TASK_SIZE
or
- cmp r4, #TASK_SIZE
+ ldr r0, =TASK_SIZE
+ cmp r4, r0
this is done to avoid the immediate #TASK_SIZE that need to
fit into a limited number of bits.
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Ard Biesheuvel <ardb@kernel.org> # QEMU/KVM/mach-virt/LPAE/8G
Tested-by: Florian Fainelli <f.fainelli@gmail.com> # Brahma SoCs
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de> # i.MX6Q
Reported-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Consolidate the user access assembly code to asm/uaccess-asm.h. This
moves the csdb, check_uaccess, uaccess_mask_range_ptr, uaccess_enable,
uaccess_disable, uaccess_save, uaccess_restore macros, and creates two
new ones for exception entry and exit - uaccess_entry and uaccess_exit.
This makes the uaccess_save and uaccess_restore macros private to
asm/uaccess-asm.h.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT.
Both PREEMPT and PREEMPT_RT require the same functionality which today
depends on CONFIG_PREEMPT.
Switch the entry code, cache over to use CONFIG_PREEMPTION and add output
in show_stack() for PREEMPT_RT.
[bigeasy: +traps.c]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20191015191821.11479-2-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Converts ARM the text files to ReST, preparing them to be an
architecture book.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Reviewed-by Corentin Labbe <clabbe.montjoie@gmail.com> # For sun4i-ss
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use unified assembler syntax (UAL) in assembly files. Divided
syntax is considered deprecated. This will also allow to build
the kernel using LLVM's integrated assembler.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
The changes to automatically test for working stack protector compiler
support in the Kconfig files removed the special STACKPROTECTOR_AUTO
option that picked the strongest stack protector that the compiler
supported.
That was all a nice cleanup - it makes no sense to have the AUTO case
now that the Kconfig phase can just determine the compiler support
directly.
HOWEVER.
It also meant that doing "make oldconfig" would now _disable_ the strong
stackprotector if you had AUTO enabled, because in a legacy config file,
the sane stack protector configuration would look like
CONFIG_HAVE_CC_STACKPROTECTOR=y
# CONFIG_CC_STACKPROTECTOR_NONE is not set
# CONFIG_CC_STACKPROTECTOR_REGULAR is not set
# CONFIG_CC_STACKPROTECTOR_STRONG is not set
CONFIG_CC_STACKPROTECTOR_AUTO=y
and when you ran this through "make oldconfig" with the Kbuild changes,
it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had
been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just
CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version
used to be disabled (because it was really enabled by AUTO), and would
disable it in the new config, resulting in:
CONFIG_HAVE_CC_STACKPROTECTOR=y
CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
CONFIG_CC_STACKPROTECTOR=y
# CONFIG_CC_STACKPROTECTOR_STRONG is not set
CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
That's dangerously subtle - people could suddenly find themselves with
the weaker stack protector setup without even realizing.
The solution here is to just rename not just the old RECULAR stack
protector option, but also the strong one. This does that by just
removing the CC_ prefix entirely for the user choices, because it really
is not about the compiler support (the compiler support now instead
automatially impacts _visibility_ of the options to users).
This results in "make oldconfig" actually asking the user for their
choice, so that we don't have any silent subtle security model changes.
The end result would generally look like this:
CONFIG_HAVE_CC_STACKPROTECTOR=y
CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
CONFIG_STACKPROTECTOR=y
CONFIG_STACKPROTECTOR_STRONG=y
CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
where the "CC_" versions really are about internal compiler
infrastructure, not the user selections.
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Avoid adding kprobes to any of the kernel entry/exit or startup
assembly code, or code in the identity-mapped region. This code does
not conform to the standard C conventions, which means that the
expectations of the kprobes code is not forfilled.
Placing kprobes at some of these locations results in the kernel trying
to return to userspace addresses while retaining the CPU in kernel mode.
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Robert Jarzmik reports that his PXA25x system fails to boot with 4.12,
failing at __flush_whole_cache in arch/arm/mm/proc-xscale.S:215:
0xc0019e20 <+0>: ldr r1, [pc, #788]
0xc0019e24 <+4>: ldr r0, [r1] <== here
with r1 containing 0xc06f82cd, which is the address of "clean_addr".
Examination of the System.map shows:
c06f22c8 D user_pmd_table
c06f22cc d __warned.19178
c06f22cd d clean_addr
indicating that a .data.unlikely section has appeared just before the
.data section from proc-xscale.S. According to objdump -h, it appears
that our assembly files default their .data alignment to 2**0, which
is bad news if the preceding .data section size is not power-of-2
aligned at link time.
Add the appropriate .align directives to all assembly files in arch/arm
that are missing them where we require an appropriate alignment.
Reported-by: Robert Jarzmik <robert.jarzmik@free.fr>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
With the new task struct randomization, we can run into a build
failure for certain random seeds, which will place fields beyond
the allow immediate size in the assembly:
arch/arm/kernel/entry-armv.S: Assembler messages:
arch/arm/kernel/entry-armv.S:803: Error: bad immediate value for offset (4096)
Only two constants in asm-offset.h are affected, and I'm changing
both of them here to work correctly in all configurations.
One more macro has the problem, but is currently unused, so this
removes it instead of adding complexity.
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[kees: Adjust commit log slightly]
Signed-off-by: Kees Cook <keescook@chromium.org>
During boot, sometimes the kernel will test to see if an instruction
causes an undefined instruction exception. Unfortunately, the exit
path for these exceptions did not restore the address limit, which
causes the rootfs mount code to fail. Fix the missing address limit
restoration.
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
When we enter an exception, the current address limit should not apply
to the exception context: if the exception context wishes to access
kernel space via the user accessors (eg, perf code), it must explicitly
request such access.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Since the privileged mode pt_regs are an extended version of the saved
userland pt_regs, introduce a new svc_pt_regs structure to describe this
layout.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
S_FRAME_SIZE is no longer the size of the kernel stack frame, so this
name is misleading. It is the size of the kernel pt_regs structure.
Name it so.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Commit b9b32bf70f ("ARM: use linker magic for vectors and vector stubs")
updated the linker script to emit the .vectors and .stubs sections into a
VMA range that is zero based and disjoint from the normal static kernel
region. The reason for that was that this way, the sections can be placed
exactly 4 KB apart, while the payload of the .vectors section is only 32
bytes.
Since the symbols that are part of the .stubs section are emitted into the
kallsyms table, they appear with zero based addresses as well, e.g.,
00001004 t vector_rst
00001020 t vector_irq
000010a0 t vector_dabt
00001120 t vector_pabt
000011a0 t vector_und
00001220 t vector_addrexcptn
00001240 t vector_fiq
00001240 T vector_fiq_offset
As this confuses perf when it accesses the kallsyms tables, commit
7122c3e915 ("scripts/link-vmlinux.sh: only filter kernel symbols for
arm") implemented a somewhat ugly special case for ARM, where the value
of CONFIG_PAGE_OFFSET is passed to scripts/kallsyms, and symbols whose
addresses are below it are filtered out. Note that this special case only
applies to CONFIG_XIP_KERNEL=n, not because the issue the patch addresses
exists only in that case, but because finding a limit below which to apply
the filtering is not entirely straightforward.
Since the .vectors and .stubs sections contain position independent code
that is never executed in place, we can emit it at its most likely runtime
VMA (for more recent CPUs), which is 0xffff0000 for the vector table and
0xffff1000 for the stubs. Not only does this fix the perf issue with
kallsyms, allowing us to drop the special case in scripts/kallsyms
entirely, it also gives debuggers a more realistic view of the address
space, and setting breakpoints or single stepping through code in the
vector table or the stubs is more likely to work as expected on CPUs that
use a high vector address. E.g.,
00001240 A vector_fiq_offset
...
c0c35000 T __init_begin
c0c35000 T __vectors_start
c0c35020 T __stubs_start
c0c35020 T __vectors_end
c0c352e0 T _sinittext
c0c352e0 T __stubs_end
...
ffff1004 t vector_rst
ffff1020 t vector_irq
ffff10a0 t vector_dabt
ffff1120 t vector_pabt
ffff11a0 t vector_und
ffff1220 t vector_addrexcptn
ffff1240 T vector_fiq
(Note that vector_fiq_offset is now an absolute symbol, which kallsyms
already ignores by default)
The LMA footprint is identical with or without this change, only the VMAs
are different:
Before:
Idx Name Size VMA LMA File off Algn
...
14 .notes 00000024 c0c34020 c0c34020 00a34020 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
15 .vectors 00000020 00000000 c0c35000 00a40000 2**1
CONTENTS, ALLOC, LOAD, READONLY, CODE
16 .stubs 000002c0 00001000 c0c35020 00a41000 2**5
CONTENTS, ALLOC, LOAD, READONLY, CODE
17 .init.text 0006b1b8 c0c352e0 c0c352e0 00a452e0 2**5
CONTENTS, ALLOC, LOAD, READONLY, CODE
...
After:
Idx Name Size VMA LMA File off Algn
...
14 .notes 00000024 c0c34020 c0c34020 00a34020 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
15 .vectors 00000020 ffff0000 c0c35000 00a40000 2**1
CONTENTS, ALLOC, LOAD, READONLY, CODE
16 .stubs 000002c0 ffff1000 c0c35020 00a41000 2**5
CONTENTS, ALLOC, LOAD, READONLY, CODE
17 .init.text 0006b1b8 c0c352e0 c0c352e0 00a452e0 2**5
CONTENTS, ALLOC, LOAD, READONLY, CODE
...
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Commit b9b32bf70f ("ARM: use linker magic for vectors and vector stubs")
introduced new global definitions of __vectors_start and __stubs_start,
and changed the existing ones to have internal linkage only. However, these
symbols are still visible to kallsyms, and due to the way the .vectors and
.stubs sections are emitted at the base of the VMA space, these duplicate
definitions have conflicting values.
$ nm -n vmlinux |grep -E __vectors|__stubs
00000000 t __vectors_start
00001000 t __stubs_start
c0e77000 T __vectors_start
c0e77020 T __stubs_start
This is completely harmless by itself, since the wrong values are local
symbols that cannot be referenced by other object files directly. However,
since these symbols are also listed in the kallsyms symbol table in some
cases (i.e., CONFIG_KALLSYMS_ALL=y and CONFIG_XIP_KERNEL=y), having these
conflicting values can be confusing. So either remove them, or make them
strictly local.
Acked-by: Chris Brandt <chris.brandt@renesas.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Mark Brand reports that a NEEDS_SYSCALL_FOR_CMPXCHG enabled kernel would
open a security hole in the ghost syscall used to implement cmpxchg, as
it fails to validate the user pointer.
However, in order for this option to be enabled, you'd need to be
building a pre-ARMv6 kernel with SMP support. There is only one system
known which fits that, which is an early ARM SMP FPGA implementation
based on the ARM926T.
In any case, the Kconfig does not allow SMP to be enabled for pre-ARMv6
systems.
Moreover, even if NEEDS_SYSCALL_FOR_CMPXCHG were to be enabled, the
kernel would not build as __ARM_NR_cmpxchg64 is not defined.
The simple answer is to remove the buggy code.
Reported-by: Mark Brand <markbrand@google.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Provide hooks into the kernel entry and exit paths to permit control
of userspace visibility to the kernel. The intended use is:
- on entry to kernel from user, uaccess_disable will be called to
disable userspace visibility
- on exit from kernel to user, uaccess_enable will be called to
enable userspace visibility
- on entry from a kernel exception, uaccess_save_and_disable will be
called to save the current userspace visibility setting, and disable
access
- on exit from a kernel exception, uaccess_restore will be called to
restore the userspace visibility as it was before the exception
occurred.
These hooks allows us to keep userspace visibility disabled for the
vast majority of the kernel, except for localised regions where we
want to explicitly access userspace.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Rather than modifying both the domain access control register and our
per-thread copy, modify only the domain access control register, and
use the per-thread copy to save and restore the register over context
switches. We can also avoid the explicit initialisation of the
init thread_info structure.
This allows us to avoid needing to gain access to the thread information
at the uaccess control sites.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Pull ARM updates from Russell King:
"These are late by a week; they should have been merged during the
merge window, but unfortunately, the ARM kernel build/boot farms were
indicating random failures, and it wasn't clear whether the cause was
something in these changes or something during the merge window.
This is a set of merge window fixes with some documentation additions"
* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
ARM: avoid unwanted GCC memset()/memcpy() optimisations for IO variants
ARM: pgtable: document mapping types
ARM: io: convert ioremap*() to functions
ARM: io: fix ioremap_wt() implementation
ARM: io: document ARM specific behaviour of ioremap*() implementations
ARM: fix lockdep unannotated irqs-off warning
ARM: 8397/1: fix vdsomunge not to depend on glibc specific error.h
ARM: add helpful message when truncating physical memory
ARM: add help text for HIGHPTE configuration entry
ARM: fix DEBUG_SET_MODULE_RONX build dependencies
ARM: 8396/1: use phys_addr_t in pfn_to_kaddr()
ARM: 8394/1: update memblock limit after mapping lowmem
ARM: 8393/1: smp: Fix suspicious RCU usage with ipi tracepoints
Wolfram Sang reported an unannotated irqs-off warning from lockdep:
WARNING: CPU: 0 PID: 282 at kernel/locking/lockdep.c:3557 check_flags+0x84/0x1f4()
DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)
CPU: 0 PID: 282 Comm: rcS Tainted: G W 4.1.0-00002-g5b076054611833 #179
Hardware name: Generic Emma Mobile EV2 (Flattened Device Tree)
Backtrace:
[<c0012c94>] (dump_backtrace) from [<c0012e3c>] (show_stack+0x18/0x1c)
r6:c02dcc67 r5:00000009 r4:00000000 r3:00400000
[<c0012e24>] (show_stack) from [<c02510c8>] (dump_stack+0x20/0x28)
[<c02510a8>] (dump_stack) from [<c0022c44>] (warn_slowpath_common+0x8c/0xb4)
[<c0022bb8>] (warn_slowpath_common) from [<c0022cd8>] (warn_slowpath_fmt+0x38/0x40)
r8:c780f470 r7:00000000 r6:00000000 r5:c03b0570 r4:c0b7ec04
[<c0022ca4>] (warn_slowpath_fmt) from [<c004cd38>] (check_flags+0x84/0x1f4)
r3:c02e13d8 r2:c02dceaa
[<c004ccb4>] (check_flags) from [<c0050e50>] (lock_acquire+0x4c/0xbc)
r5:00000000 r4:60000193
[<c0050e04>] (lock_acquire) from [<c0256000>] (_raw_spin_lock+0x34/0x44)
r9:000a8d5c r8:00000001 r7:c7806000 r6:c780f460 r5:c03b06a0 r4:c780f460
[<c0255fcc>] (_raw_spin_lock) from [<c005a8cc>] (handle_fasteoi_irq+0x20/0x11c)
r4:c780f400
[<c005a8ac>] (handle_fasteoi_irq) from [<c0057a4c>] (generic_handle_irq+0x28/0x38)
r6:00000000 r5:c03b038c r4:00000012 r3:c005a8ac
[<c0057a24>] (generic_handle_irq) from [<c0057ae4>] (__handle_domain_irq+0x88/0xa8)
r4:00000000 r3:00000026
[<c0057a5c>] (__handle_domain_irq) from [<c000a3cc>] (gic_handle_irq+0x40/0x58)
r8:10c5347d r7:10c5347d r6:c35b1fb0 r5:c03a6304 r4:c8802000 r3:c35b1fb0
[<c000a38c>] (gic_handle_irq) from [<c0013bc8>] (__irq_usr+0x48/0x60)
Exception stack(0xc35b1fb0 to 0xc35b1ff8)
1fa0: 00000061 00000000 000ab736 00000066
1fc0: 00000061 000aa1f0 000a8d54 000a8d54 000a8d88 000a8d5c 000a8cc8 000a8d68
1fe0: 72727272 bef8a528 000398c0 00031334 20000010 ffffffff
r6:ffffffff r5:20000010 r4:00031334 r3:00000061
---[ end trace cb88537fdc8fa202 ]---
possible reason: unannotated irqs-off.
irq event stamp: 769
hardirqs last enabled at (769): [<c000f82c>] ret_fast_syscall+0x2c/0x54
hardirqs last disabled at (768): [<c000f80c>] ret_fast_syscall+0xc/0x54
softirqs last enabled at (0): [<c0020ec4>] copy_process.part.65+0x2e8/0x11dc
softirqs last disabled at (0): [< (null)>] (null)
His kernel configuration had:
CONFIG_PROVE_LOCKING=y
CONFIG_TRACE_IRQFLAGS=y
but no IRQSOFF_TRACER, which means entry from userspace can result in the
kernel seeing IRQs off without being notified of that change of state.
Change the IRQSOFF ifdef in the usr_entry macro to TRACE_IRQFLAGS instead.
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Merge tag 'module-misc-v4.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
Pull init.h/module.h fragility fixes from Paul Gortmaker:
"Fixup various init.h misuses that are fragile wrt code moving to
module.h
What started as a removal of no longer required include <linux/init.h>
due to the earlier __cpuinit and __devinit removal led to the
observation that some module specfic support was living in init.h
itself, thus preventing the full removal from introducing compile
regressions.
This series includes a few final fixups needed prior to the relocation
of the modular init code from <init.h> to <module.h>. These are
things that weren't easily categorized into any of the other previous
series categories already requested for pull.
That said, each fixup branch (including this one) is independent and
there are no ordering constraints. Only the final code relocation
(which is NOT in this pull) requires that all my cleanup branches be
merged first"
* tag 'module-misc-v4.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
tile: add init.h to usb.c to avoid compile failure
arm: fix implicit #include <linux/init.h> in entry asm.
x86: replace __init_or_module with __init in non-modular vsmp_64.c
They use the "_INIT" macro and friends, and hence need to
source this header file, vs. relying on getting it implicitly.
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
BSYM() was invented to allow us to work around a problem with the
assembler, where local symbols resolved by the assembler for the 'adr'
instruction did not take account of their ISA.
Since we don't want BSYM() used elsewhere, replace BSYM() with a new
macro 'badr', which is like the 'adr' pseudo-op, but with the BSYM()
mechanics integrated into it. This ensures that the BSYM()-ification
is only used in conjunction with 'adr'.
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This moves all fixup snippets to the .text.fixup section, which is
a special section that gets emitted along with the .text section
for each input object file, i.e., the snippets are kept much closer
to the code they refer to, which helps prevent linker failure on
large kernels.
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch prohibits probing instructions for which the stack
requirements are unable to be determined statically. Some test cases
are found not work again after the modification, this patch also
removes them.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
If we are not changing the control register value, avoid writing to it.
Writes to the control register can be very expensive, taking around a
hundred cycles or so.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch introduces a new default FIQ handler that is structured in a
similar way to the existing ARM exception handler and result in the FIQ
being handled by C code running on the SVC stack (despite this code run
in the FIQ handler is subject to severe limitations with respect to
locking making normal interaction with the kernel impossible).
This default handler allows concepts that on x86 would be handled using
NMIs to be realized on ARM.
Credit:
This patch is a near complete re-write of a patch originally
provided by Anton Vorontsov. Today only a couple of small fragments
survive, however without Anton's work to build from this patch would
not exist. Thanks also to Russell King for spoonfeeding me a variety
of fixes during the review cycle.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARMv6 and greater introduced a new instruction ("bx") which can be used
to return from function calls. Recent CPUs perform better when the
"bx lr" instruction is used rather than the "mov pc, lr" instruction,
and this sequence is strongly recommended to be used by the ARM
architecture manual (section A.4.1.1).
We provide a new macro "ret" with all its variants for the condition
code which will resolve to the appropriate instruction.
Rather than doing this piecemeal, and miss some instances, change all
the "mov pc" instances to use the new macro, with the exception of
the "movs" instruction and the kprobes code. This allows us to detect
the "mov pc, lr" case and fix it up - and also gives us the possibility
of deploying this for other registers depending on the CPU selection.
Reported-by: Will Deacon <will.deacon@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S
Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385
Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci
Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M
Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
cr_no_alignment is really only used by the alignment code. Since we no
longer change the setting of cr_alignment after boot, we can localise
this to alignment.c
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
We will reach fixup handler when one thread(say cpu0) caused an undefined exception, while another thread(say cpu1) is unmmaping the page.
Fixup handler returns to the next userspace instruction which has caused the undef execption, rather than going to the same instruction.
ARM ARM says that after undefined exception, the PC will be pointing
to the next instruction. ie +4 offset in case of ARM and +2 in case of Thumb
And there is no correction offset passed to vector_stub in case of
undef exception.
File: arch/arm/kernel/entry-armv.S +1085
vector_stub und, UND_MODE
During an undefined exception, in normal scenario(ie when ldrt
instruction does not cause an abort) after resorting the context in
VFP hardware, the PC is modified as show below before jumping to
ret_from_exception which is in r9.
File: arch/arm/vfp/vfphw.S +169
@ The context stored in the VFP hardware is up to date with this thread
vfp_hw_state_valid:
tst r1, #FPEXC_EX
bne process_exception @ might as well handle the pending
@ exception before retrying branch
@ out before setting an FPEXC that
@ stops us reading stuff
VFPFMXR FPEXC, r1 @ Restore FPEXC last
sub r2, r2, #4 @ Retry current instruction - if Thumb
str r2, [sp, #S_PC] @ mode it's two 16-bit instructions,
@ else it's one 32-bit instruction, so
@ always subtract 4 from the following
@ instruction address.
But if ldrt results in an abort, we reach the fixup handler and return
to ret_from_execption without correcting the pc.
This patch modifes the fixup handler to re-execute the same instruction which caused undefined execption.
Signed-off-by: Vinayak Menon <vinayakm.list@gmail.com>
Signed-off-by: Arun KS <getarunks@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The Undef abort handler in the kernel reads the undefined instruction
from user space. If the page table was modified from another CPU, the
user access could fail and do_page_fault() will be executed with
interrupts disabled. This can potentially deadlock on ARM11MPCore or on
Cortex-A15 with erratum 798181 workaround enabled (both implying IPI for
TLB maintenance with page table lock held).
This patch enables the IRQs in __und_usr before attempting to read the
instruction from user space.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Arun KS <getarunks@gmail.com>
Cc: Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ryan Mallon <rmallon@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
__und_usr_thumb function deals with thumb2 opcodes. In case of BE
image, it needs to byteswap half word thumb2 encoded instructions
before further processing them.
Without this fix BE image user-land thread executing first VFP
instruction encoded in thumb2 fails with SIGILL, because kernel
does not recognize instruction and does not enable VFP.
Reported-by: Corey Melton <comelton@cisco.com>
Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The exception handling code fails to clear the IT state, potentially
leading to incorrect execution of the fixup if the size of the IT
block is more than one.
Let fixup_exception do the IT sanitizing if a fixup has been found,
and restore CPSR from the stack when returning from a data abort.
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add ARM_BE8() helper to wrap any code conditional on being
compile when CONFIG_ARM_ENDIAN_BE8 is selected and convert
existing places where this is to use it.
Acked-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Fix yet another build failure caused by a weird set of configuration
settings:
LD init/built-in.o
arch/arm/kernel/built-in.o: In function `__dabt_usr':
/home/tom3q/kernel/arch/arm/kernel/entry-armv.S:377: undefined reference to `kuser_cmpxchg64_fixup'
arch/arm/kernel/built-in.o: In function `__irq_usr':
/home/tom3q/kernel/arch/arm/kernel/entry-armv.S:387: undefined reference to `kuser_cmpxchg64_fixup'
caused by:
CONFIG_KUSER_HELPERS=n
CONFIG_CPU_32v6K=n
CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG=n
Reported-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Linus Torvalds
Mark Rutland
Ard Biesheuvel
Arnd Bergmann
Linus Walleij
Russell King
Thomas Gleixner
Mauro Carvalho Chehab
Stefan Agner
Palmer Dabbelt
Ard Biesheuvel
Russell King
Paul Gortmaker
Wang Nan
Daniel Thompson
Arun K S
Catalin Marinas
Victor Kamensky
Marc Zyngier
Ben Dooks