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x86 vDSO: ia32 sysenter_return

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This changes the 64-bit kernel's support for the 32-bit sysenter
instruction to use stored fields rather than constants for the
user-mode return address, as the 32-bit kernel does.  This adds a
sysenter_return field to struct thread_info, as 32-bit has.  There
is no observable effect from this yet.  It makes the assembly code
independent of the 32-bit vDSO mapping address, paving the way for
making the vDSO address vary as it does on the 32-bit kernel.

[ akpm@linux-foundation.org: build fix on !CONFIG_IA32_EMULATION ]

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Roland McGrath 2008-01-30 13:30:43 +01:00 committed by Ingo Molnar
parent 0aa97fb226
commit 36197c92a2
4 changed files with 13 additions and 4 deletions
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7
arch/x86/ia32/ia32entry.S
View File

@ -12,7 +12,6 @@
#include <asm/ia32_unistd.h>
#include <asm/thread_info.h>
#include <asm/segment.h>
#include <asm/vsyscall32.h>
#include <asm/irqflags.h>
#include <linux/linkage.h>
@ -104,7 +103,7 @@ ENTRY(ia32_sysenter_target)
pushfq
CFI_ADJUST_CFA_OFFSET 8
/*CFI_REL_OFFSET rflags,0*/
movl $VSYSCALL32_SYSEXIT, %r10d
movl 8*3-THREAD_SIZE+threadinfo_sysenter_return(%rsp), %r10d
CFI_REGISTER rip,r10
pushq $__USER32_CS
CFI_ADJUST_CFA_OFFSET 8
@ -142,6 +141,8 @@ sysenter_do_call:
andl $~TS_COMPAT,threadinfo_status(%r10)
/* clear IF, that popfq doesn't enable interrupts early */
andl $~0x200,EFLAGS-R11(%rsp)
movl RIP-R11(%rsp),%edx /* User %eip */
CFI_REGISTER rip,rdx
RESTORE_ARGS 1,24,1,1,1,1
popfq
CFI_ADJUST_CFA_OFFSET -8
@ -149,8 +150,6 @@ sysenter_do_call:
popq %rcx /* User %esp */
CFI_ADJUST_CFA_OFFSET -8
CFI_REGISTER rsp,rcx
movl $VSYSCALL32_SYSEXIT,%edx /* User %eip */
CFI_REGISTER rip,rdx
TRACE_IRQS_ON
swapgs
sti /* sti only takes effect after the next instruction */

4
arch/x86/ia32/syscall32.c
View File

@ -46,6 +46,10 @@ int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
VM_ALWAYSDUMP,
syscall32_pages);
if (ret == 0) {
current->mm->context.vdso = (void __user *)VSYSCALL32_BASE;
current_thread_info()->sysenter_return = VSYSCALL32_SYSEXIT;
}
up_write(&mm->mmap_sem);
return ret;
}

3
arch/x86/kernel/asm-offsets_64.c
View File

@ -46,6 +46,9 @@ int main(void)
ENTRY(addr_limit);
ENTRY(preempt_count);
ENTRY(status);
#ifdef CONFIG_IA32_EMULATION
ENTRY(sysenter_return);
#endif
BLANK();
#undef ENTRY
#define ENTRY(entry) DEFINE(pda_ ## entry, offsetof(struct x8664_pda, entry))

3
include/asm-x86/thread_info_64.h
View File

@ -33,6 +33,9 @@ struct thread_info {
mm_segment_t addr_limit;
struct restart_block restart_block;
#ifdef CONFIG_IA32_EMULATION
void __user *sysenter_return;
#endif
};
#endif