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Commit 36197c92 authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
Browse files

x86 vDSO: ia32 sysenter_return 



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: default avatarRoland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 0aa97fb2

arch/x86/ia32/ia32entry.S

+3 −4
Original line number Diff line number Diff line
@@ -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 */

arch/x86/ia32/syscall32.c

+4 −0
Original line number Diff line number Diff line
@@ -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;

}

arch/x86/kernel/asm-offsets_64.c

+3 −0
Original line number Diff line number Diff line
@@ -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))

include/asm-x86/thread_info_64.h

+3 −0
Original line number Diff line number Diff line
@@ -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