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x86_64: further cleanup of 32-bit compat syscall mechanisms

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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 <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Jeremy Fitzhardinge 2008-07-12 02:22:00 -07:00 committed by Ingo Molnar
parent 71415c6a08
commit 6a52e4b1cd
7 changed files with 35 additions and 22 deletions
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2
arch/x86/kernel/cpu/amd_64.c
View file

@ -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)

3
arch/x86/kernel/cpu/common_64.c
View file

@ -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);

2
arch/x86/vdso/Makefile
View file

@ -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

19
arch/x86/vdso/vdso32-setup.c
View file

@ -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);

13
arch/x86/vdso/vdso32.S
View file

@ -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:

10
arch/x86/xen/setup.c
View file

@ -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
}

8
include/asm-x86/vdso.h
View file

@ -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 */