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| Started by | Josh Poimboeuf <jpoimboe@redhat.com> |
|---|---|
| First post | 2016-08-12 16:40 +0200 |
| Last post | 2016-08-13 00:10 +0200 |
| Articles | 2 — 2 participants |
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[PATCH v3 04/51] x86/asm/head: use a common function for starting CPUs Josh Poimboeuf <jpoimboe@redhat.com> - 2016-08-12 16:40 +0200
Re: [PATCH v3 04/51] x86/asm/head: use a common function for starting CPUs Nilay Vaish <nilayvaish@gmail.com> - 2016-08-13 00:10 +0200
| From | Josh Poimboeuf <jpoimboe@redhat.com> |
|---|---|
| Date | 2016-08-12 16:40 +0200 |
| Subject | [PATCH v3 04/51] x86/asm/head: use a common function for starting CPUs |
| Message-ID | <s5lMS-2Ra-31@gated-at.bofh.it> |
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 <jpoimboe@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 -- 2.7.4
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| From | Nilay Vaish <nilayvaish@gmail.com> |
|---|---|
| Date | 2016-08-13 00:10 +0200 |
| Message-ID | <s5sOl-7GA-5@gated-at.bofh.it> |
| In reply to | #1461217 |
On 12 August 2016 at 09:28, Josh Poimboeuf <jpoimboe@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 <jpoimboe@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
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