On December 14, 2016 12:36:58 AM PST, tip-bot for Josh Poimboeuf <tipbot@xxxxxxxxx> wrote: >Commit-ID: ec2d86a9b646d93f1948569f368e2c6f5449e6c7 >Gitweb: >http://git.kernel.org/tip/ec2d86a9b646d93f1948569f368e2c6f5449e6c7 >Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> >AuthorDate: Tue, 13 Dec 2016 21:25:35 -0600 >Committer: Ingo Molnar <mingo@xxxxxxxxxx> >CommitDate: Wed, 14 Dec 2016 08:48:05 +0100 > >x86/boot/64: Use 'push' instead of 'call' in start_cpu() > >start_cpu() pushes a text address on the stack so that stack traces >from >idle tasks will show start_cpu() at the end. But it uses a call >instruction to do that, which is rather obtuse. Use a straightforward >push instead. > >Suggested-by: Borislav Petkov <bp@xxxxxxxxx> >Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> >Cc: Andy Lutomirski <luto@xxxxxxxxxx> >Cc: Brian Gerst <brgerst@xxxxxxxxx> >Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> >Cc: H. Peter Anvin <hpa@xxxxxxxxx> >Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> >Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> >Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> >Link: >http://lkml.kernel.org/r/4d8a1952759721d42d1e62ba9e4a7e3ac5df8574.1481685203.git.jpoimboe@xxxxxxxxxx >Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> >--- > arch/x86/kernel/head_64.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > >diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S >index 90de288..1facaf4 100644 >--- a/arch/x86/kernel/head_64.S >+++ b/arch/x86/kernel/head_64.S >@@ -298,7 +298,7 @@ ENTRY(start_cpu) > * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect, > * address given in m16:64. > */ >- call 1f # put return address on stack for unwinder >+ pushq $1f # put return address on stack for unwinder > 1: xorq %rbp, %rbp # clear frame pointer > movq initial_code(%rip), %rax > pushq $__KERNEL_CS # set correct cs This adds another relocation to the kernel. I hope this is safe at this point in the code? -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|