From 6a52e4b1cddd90fbfde8fb67021657936ee74b07 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Sat, 12 Jul 2008 02:22:00 -0700 Subject: [PATCH] x86_64: further cleanup of 32-bit compat syscall mechanisms AMD only supports "syscall" from 32-bit compat usermode. Intel and Centaur(?) only support "sysenter" from 32-bit compat usermode. Set the X86 feature bits accordingly, and set up the vdso in accordance with those bits. On the offchance we run on in a 64-bit environment which supports neither syscall nor sysenter from 32-bit mode, then fall back to the int $0x80 vdso. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/amd_64.c | 2 ++ arch/x86/kernel/cpu/common_64.c | 3 --- arch/x86/vdso/Makefile | 2 +- arch/x86/vdso/vdso32-setup.c | 19 +++++++++---------- arch/x86/vdso/vdso32.S | 13 ++++++++----- arch/x86/xen/setup.c | 10 +++++++--- include/asm-x86/vdso.h | 8 ++++++++ 7 files changed, 35 insertions(+), 22 deletions(-) diff --git a/arch/x86/kernel/cpu/amd_64.c b/arch/x86/kernel/cpu/amd_64.c index 7c36fb8a28d4..d1692b2a41ff 100644 --- a/arch/x86/kernel/cpu/amd_64.c +++ b/arch/x86/kernel/cpu/amd_64.c @@ -115,6 +115,8 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c) /* c->x86_power is 8000_0007 edx. Bit 8 is constant TSC */ if (c->x86_power & (1<<8)) set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); + + set_cpu_cap(c, X86_FEATURE_SYSCALL32); } static void __cpuinit init_amd(struct cpuinfo_x86 *c) diff --git a/arch/x86/kernel/cpu/common_64.c b/arch/x86/kernel/cpu/common_64.c index 15419cd3c5a4..736f50fa433d 100644 --- a/arch/x86/kernel/cpu/common_64.c +++ b/arch/x86/kernel/cpu/common_64.c @@ -317,9 +317,6 @@ static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c) c->x86_phys_bits = eax & 0xff; } - /* Assume all 64-bit CPUs support 32-bit syscall */ - set_cpu_cap(c, X86_FEATURE_SYSCALL32); - if (c->x86_vendor != X86_VENDOR_UNKNOWN && cpu_devs[c->x86_vendor]->c_early_init) cpu_devs[c->x86_vendor]->c_early_init(c); diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile index b7ad9f89d21f..4d6ef0a336d6 100644 --- a/arch/x86/vdso/Makefile +++ b/arch/x86/vdso/Makefile @@ -62,7 +62,7 @@ $(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE # Build multiple 32-bit vDSO images to choose from at boot time. # obj-$(VDSO32-y) += vdso32-syms.lds -vdso32.so-$(CONFIG_X86_32) += int80 +vdso32.so-$(VDSO32-y) += int80 vdso32.so-$(CONFIG_COMPAT) += syscall vdso32.so-$(VDSO32-y) += sysenter diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c index 0bce5429a515..513f330c5832 100644 --- a/arch/x86/vdso/vdso32-setup.c +++ b/arch/x86/vdso/vdso32-setup.c @@ -193,17 +193,12 @@ static __init void relocate_vdso(Elf32_Ehdr *ehdr) } } -/* - * These symbols are defined by vdso32.S to mark the bounds - * of the ELF DSO images included therein. - */ -extern const char vdso32_default_start, vdso32_default_end; -extern const char vdso32_sysenter_start, vdso32_sysenter_end; static struct page *vdso32_pages[1]; #ifdef CONFIG_X86_64 #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SYSENTER32)) +#define vdso32_syscall() (boot_cpu_has(X86_FEATURE_SYSCALL32)) /* May not be __init: called during resume */ void syscall32_cpu_init(void) @@ -226,6 +221,7 @@ static inline void map_compat_vdso(int map) #else /* CONFIG_X86_32 */ #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP)) +#define vdso32_syscall() (0) void enable_sep_cpu(void) { @@ -296,12 +292,15 @@ int __init sysenter_setup(void) gate_vma_init(); #endif - if (!vdso32_sysenter()) { - vsyscall = &vdso32_default_start; - vsyscall_len = &vdso32_default_end - &vdso32_default_start; - } else { + if (vdso32_syscall()) { + vsyscall = &vdso32_syscall_start; + vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start; + } else if (vdso32_sysenter()){ vsyscall = &vdso32_sysenter_start; vsyscall_len = &vdso32_sysenter_end - &vdso32_sysenter_start; + } else { + vsyscall = &vdso32_int80_start; + vsyscall_len = &vdso32_int80_end - &vdso32_int80_start; } memcpy(syscall_page, vsyscall, vsyscall_len); diff --git a/arch/x86/vdso/vdso32.S b/arch/x86/vdso/vdso32.S index 1e36f72cab86..2ce5f82c333b 100644 --- a/arch/x86/vdso/vdso32.S +++ b/arch/x86/vdso/vdso32.S @@ -2,14 +2,17 @@ __INITDATA - .globl vdso32_default_start, vdso32_default_end -vdso32_default_start: -#ifdef CONFIG_X86_32 + .globl vdso32_int80_start, vdso32_int80_end +vdso32_int80_start: .incbin "arch/x86/vdso/vdso32-int80.so" -#else +vdso32_int80_end: + + .globl vdso32_syscall_start, vdso32_syscall_end +vdso32_syscall_start: +#ifdef CONFIG_COMPAT .incbin "arch/x86/vdso/vdso32-syscall.so" #endif -vdso32_default_end: +vdso32_syscall_end: .globl vdso32_sysenter_start, vdso32_sysenter_end vdso32_sysenter_start: diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index 3e11779755c3..e3648e64a637 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -83,12 +83,16 @@ static void xen_idle(void) /* * Set the bit indicating "nosegneg" library variants should be used. + * We only need to bother in pure 32-bit mode; compat 32-bit processes + * can have un-truncated segments, so wrapping around is allowed. */ static void __init fiddle_vdso(void) { -#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) - extern const char vdso32_default_start; - u32 *mask = VDSO32_SYMBOL(&vdso32_default_start, NOTE_MASK); +#ifdef CONFIG_X86_32 + u32 *mask; + mask = VDSO32_SYMBOL(&vdso32_int80_start, NOTE_MASK); + *mask |= 1 << VDSO_NOTE_NONEGSEG_BIT; + mask = VDSO32_SYMBOL(&vdso32_sysenter_start, NOTE_MASK); *mask |= 1 << VDSO_NOTE_NONEGSEG_BIT; #endif } diff --git a/include/asm-x86/vdso.h b/include/asm-x86/vdso.h index 86e085e003d2..8e18fb80f5e6 100644 --- a/include/asm-x86/vdso.h +++ b/include/asm-x86/vdso.h @@ -36,4 +36,12 @@ extern const char VDSO32_PRELINK[]; extern void __user __kernel_sigreturn; extern void __user __kernel_rt_sigreturn; +/* + * These symbols are defined by vdso32.S to mark the bounds + * of the ELF DSO images included therein. + */ +extern const char vdso32_int80_start, vdso32_int80_end; +extern const char vdso32_syscall_start, vdso32_syscall_end; +extern const char vdso32_sysenter_start, vdso32_sysenter_end; + #endif /* asm-x86/vdso.h */