x86/asm/entry/64: Use common code for rt_sigreturn() epilogue (31f0119b) · Commits · 戴 / test

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>

arch/x86/kernel/entry_64.S

+16 −10

Original line number	Diff line number	Diff line
		@@ -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)

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