Commit-ID: 31f0119b817f6474a7b4c48fed7588af1b62c543 Gitweb: http://git.kernel.org/tip/31f0119b817f6474a7b4c48fed7588af1b62c543 Author: Denys Vlasenko <dvlas...@redhat.com> AuthorDate: Tue, 7 Apr 2015 22:43:37 +0200 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 9 Apr 2015 10:31:24 +0200
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 <dvlas...@redhat.com> Cc: Alexei Starovoitov <a...@plumgrid.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Frederic Weisbecker <fweis...@gmail.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Kees Cook <keesc...@chromium.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Oleg Nesterov <o...@redhat.com> Cc: Steven Rostedt <rost...@goodmis.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Will Drewry <w...@chromium.org> Link: http://lkml.kernel.org/r/1428439424-7258-1-git-send-email-dvlas...@redhat.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/kernel/entry_64.S | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 3197f41..5252e60 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
