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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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19
arch/x86/vdso/vdso32-setup.c
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@@ -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);