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: 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>
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@ -12,7 +12,6 @@
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#include <asm/ia32_unistd.h>
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#include <asm/thread_info.h>
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#include <asm/segment.h>
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#include <asm/vsyscall32.h>
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#include <asm/irqflags.h>
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#include <linux/linkage.h>
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@ -104,7 +103,7 @@ ENTRY(ia32_sysenter_target)
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pushfq
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CFI_ADJUST_CFA_OFFSET 8
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/*CFI_REL_OFFSET rflags,0*/
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movl $VSYSCALL32_SYSEXIT, %r10d
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movl 8*3-THREAD_SIZE+threadinfo_sysenter_return(%rsp), %r10d
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CFI_REGISTER rip,r10
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pushq $__USER32_CS
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CFI_ADJUST_CFA_OFFSET 8
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@ -142,6 +141,8 @@ sysenter_do_call:
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andl $~TS_COMPAT,threadinfo_status(%r10)
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/* clear IF, that popfq doesn't enable interrupts early */
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andl $~0x200,EFLAGS-R11(%rsp)
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movl RIP-R11(%rsp),%edx /* User %eip */
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CFI_REGISTER rip,rdx
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RESTORE_ARGS 1,24,1,1,1,1
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popfq
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CFI_ADJUST_CFA_OFFSET -8
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@ -149,8 +150,6 @@ sysenter_do_call:
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popq %rcx /* User %esp */
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CFI_ADJUST_CFA_OFFSET -8
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CFI_REGISTER rsp,rcx
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movl $VSYSCALL32_SYSEXIT,%edx /* User %eip */
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CFI_REGISTER rip,rdx
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TRACE_IRQS_ON
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swapgs
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sti /* sti only takes effect after the next instruction */
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@ -46,6 +46,10 @@ int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
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VM_ALWAYSDUMP,
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syscall32_pages);
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if (ret == 0) {
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current->mm->context.vdso = (void __user *)VSYSCALL32_BASE;
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current_thread_info()->sysenter_return = VSYSCALL32_SYSEXIT;
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}
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up_write(&mm->mmap_sem);
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return ret;
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}
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@ -46,6 +46,9 @@ int main(void)
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ENTRY(addr_limit);
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ENTRY(preempt_count);
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ENTRY(status);
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#ifdef CONFIG_IA32_EMULATION
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ENTRY(sysenter_return);
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#endif
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BLANK();
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#undef ENTRY
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#define ENTRY(entry) DEFINE(pda_ ## entry, offsetof(struct x8664_pda, entry))
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@ -33,6 +33,9 @@ struct thread_info {
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mm_segment_t addr_limit;
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struct restart_block restart_block;
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#ifdef CONFIG_IA32_EMULATION
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void __user *sysenter_return;
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#endif
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};
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#endif
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