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| author | Denys Vlasenko <dvlasenk@redhat.com> | 2015-04-07 22:43:37 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-04-09 10:31:24 +0200 |
| commit | 31f0119b817f6474a7b4c48fed7588af1b62c543 (patch) | |
| tree | 9cabd0a1349b0852b56421d68b62c00d493654fa /arch/x86 | |
| parent | 8b3607b5b8c591d8bf045911cb7c90ecaa6e7b73 (diff) | |
| download | linux-31f0119b817f6474a7b4c48fed7588af1b62c543.tar.bz2 | |
x86/asm/entry/64: Use common code for rt_sigreturn() epilogue
Similarly to stub_execve, we can reuse the epilogue in
stub_rt_sigreturn() and stub_x32_rt_sigreturn().
Add a comment explaining why we can't eliminage SAVE_EXTRA_REGS
here.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1428439424-7258-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 26 |
1 files changed, 16 insertions, 10 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 3197f41ce320..5252e6021826 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -527,12 +527,21 @@ END(stub_execveat) */ ENTRY(stub_rt_sigreturn) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS + DEFAULT_FRAME 0, 8 + /* + * SAVE_EXTRA_REGS result is not normally needed: + * sigreturn overwrites all pt_regs->GPREGS. + * But sigreturn can fail (!), and there is no easy way to detect that. + * To make sure RESTORE_EXTRA_REGS doesn't restore garbage on error, + * we SAVE_EXTRA_REGS here. + */ + SAVE_EXTRA_REGS 8 call sys_rt_sigreturn - movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer +return_from_stub: + addq $8, %rsp + CFI_ADJUST_CFA_OFFSET -8 RESTORE_EXTRA_REGS + movq %rax,RAX(%rsp) jmp int_ret_from_sys_call CFI_ENDPROC END(stub_rt_sigreturn) @@ -540,13 +549,10 @@ END(stub_rt_sigreturn) #ifdef CONFIG_X86_X32_ABI ENTRY(stub_x32_rt_sigreturn) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS + DEFAULT_FRAME 0, 8 + SAVE_EXTRA_REGS 8 call sys32_x32_rt_sigreturn - movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer - RESTORE_EXTRA_REGS - jmp int_ret_from_sys_call + jmp return_from_stub CFI_ENDPROC END(stub_x32_rt_sigreturn) |