On 12 August 2016 at 09:28, Josh Poimboeuf <jpoim...@redhat.com> wrote: > There are two different pieces of code for starting a CPU: start_cpu0() > and the end of secondary_startup_64(). They're identical except for the > stack setup. Combine the common parts into a shared start_cpu() > function. > > Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com> > --- > arch/x86/kernel/head_64.S | 22 +++++++++++----------- > 1 file changed, 11 insertions(+), 11 deletions(-) > > diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S > index e048142..a212310 100644 > --- a/arch/x86/kernel/head_64.S > +++ b/arch/x86/kernel/head_64.S > @@ -264,13 +264,17 @@ ENTRY(secondary_startup_64) > movl $MSR_GS_BASE,%ecx > movl initial_gs(%rip),%eax > movl initial_gs+4(%rip),%edx > - wrmsr > + wrmsr > > /* rsi is pointer to real mode structure with interesting info. > pass it to C */ > movq %rsi, %rdi > - > - /* Finally jump to run C code and to be on real kernel address > + jmp start_cpu > +ENDPROC(secondary_startup_64) > + > +ENTRY(start_cpu) > + /* > + * Jump to run C code and to be on a real kernel address. > * Since we are running on identity-mapped space we have to jump > * to the full 64bit address, this is only possible as indirect > * jump. In addition we need to ensure %cs is set so we make this > @@ -299,7 +303,7 @@ ENTRY(secondary_startup_64) > pushq $__KERNEL_CS # set correct cs > pushq %rax # target address in negative space > lretq > -ENDPROC(secondary_startup_64) > +ENDPROC(start_cpu) > > #include "verify_cpu.S" > > @@ -307,15 +311,11 @@ ENDPROC(secondary_startup_64) > /* > * Boot CPU0 entry point. It's called from play_dead(). Everything has been > set > * up already except stack. We just set up stack here. Then call > - * start_secondary(). > + * start_secondary() via start_cpu(). > */ > ENTRY(start_cpu0) > - movq initial_stack(%rip),%rsp > - movq initial_code(%rip),%rax > - pushq $0 # fake return address to stop unwinder > - pushq $__KERNEL_CS # set correct cs > - pushq %rax # target address in negative space > - lretq > + movq initial_stack(%rip), %rsp > + jmp start_cpu > ENDPROC(start_cpu0) > #endif >
Josh, I think this patch looks good now, better than the previous version. Thanks for making the change. -- Nilay
