It is not legal to call anything EFI from the AP.
You might get lucky, but you are just winning the race, due to luck.
A AP safe DebugLib instance would be useful. Locks and reentrantcy
Safe.
Sent from my iPhone
> On Jul 31, 2014, at 11:23 AM, Jordan Justen <jljus...@gmail.com> wrote:
>
>> On Thu, Jul 31, 2014 at 2:58 AM, Chen Fan <chen.fan.f...@cn.fujitsu.com>
>> wrote:
>> we allocate Stack for each AP via Memory Allocation Services. then
>> we can free the temporary stack at the end.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.0
>> Signed-off-by: Chen Fan <chen.fan.f...@cn.fujitsu.com>
>> ---
>> UefiCpuPkg/CpuDxe/CpuMp.c | 14 +++++++++++++-
>> UefiCpuPkg/CpuDxe/Ia32/MpAsm.S | 2 ++
>> UefiCpuPkg/CpuDxe/X64/MpAsm.S | 7 ++++++-
>> 3 files changed, 21 insertions(+), 2 deletions(-)
>>
>> diff --git a/UefiCpuPkg/CpuDxe/CpuMp.c b/UefiCpuPkg/CpuDxe/CpuMp.c
>> index 1d1ed3a..ca92d37 100644
>> --- a/UefiCpuPkg/CpuDxe/CpuMp.c
>> +++ b/UefiCpuPkg/CpuDxe/CpuMp.c
>> @@ -19,12 +19,24 @@ VOID *mCommonStack = 0;
>> VOID *mTopOfApCommonStack = 0;
>>
>>
>> -VOID
>> +VOID*
>> EFIAPI
>> ApEntryPointInC (
>> VOID
>> )
>> {
>> + VOID *ThisCommonStack = 0;
>> + VOID *ThisTopOfApCommonStack = 0;
>> +
>> + // Allocate this processor stack space.
>> + ThisCommonStack = AllocatePages (EFI_SIZE_TO_PAGES (SIZE_64KB));
>
> Mike, Andrew, all,
>
> Can AP's use BootServices?
>
> Is it okay if they ensure the BSP is not using any services? Or, do we
> need to have the BSP do all the BootServices memory allocations?
>
>> + ASSERT(ThisCommonStack != NULL);
>> +
>> + ThisTopOfApCommonStack = (VOID*) ((UINTN)ThisCommonStack + SIZE_64KB);
>> +
>> + DEBUG((DEBUG_ERROR, "!!%d: %p\n", GetApicId(), ThisTopOfApCommonStack));
>> +
>> + return ThisTopOfApCommonStack;
>
> Can we instead use SwitchStack?
>
> My thought is ApEntryPointInC will switch the AP to its own stack and
> then call AsmApDoneWithCommonStack. The AP will never return from
> ApEntryPointInC, and it would enter a spin loop of some sort where it
> could wait to be dispatched to run code later.
>
> -Jordan
>
>> }
>>
>>
>> diff --git a/UefiCpuPkg/CpuDxe/Ia32/MpAsm.S b/UefiCpuPkg/CpuDxe/Ia32/MpAsm.S
>> index 2b3d298..8252263 100644
>> --- a/UefiCpuPkg/CpuDxe/Ia32/MpAsm.S
>> +++ b/UefiCpuPkg/CpuDxe/Ia32/MpAsm.S
>> @@ -34,7 +34,9 @@ lock btsl $0, ApStackLock
>> jc AsmApEntryPointAcquireLock
>>
>> movl (ASM_PFX(mTopOfApCommonStack)), %esp
>> + sub $0x8, %esp
>> call ASM_PFX(ApEntryPointInC)
>> + movl %eax, %esp
>>
>> cli
>>
>> diff --git a/UefiCpuPkg/CpuDxe/X64/MpAsm.S b/UefiCpuPkg/CpuDxe/X64/MpAsm.S
>> index cfad551..b03b043 100644
>> --- a/UefiCpuPkg/CpuDxe/X64/MpAsm.S
>> +++ b/UefiCpuPkg/CpuDxe/X64/MpAsm.S
>> @@ -34,7 +34,9 @@ lock btsl $0, ApStackLock
>> jc AsmApEntryPointAcquireLock
>>
>> movq (ASM_PFX(mTopOfApCommonStack)), %rsp
>> + sub $0x20, %rsp
>> call ASM_PFX(ApEntryPointInC)
>> + movq %rax, %rsp
>>
>> cli
>>
>> @@ -46,7 +48,10 @@ AsmApEntryPointShareLock:
>> decl %eax
>> jnz AsmApEntryPointShareLock
>>
>> - jmp ASM_PFX(AsmApEntryPoint)
>> + sti
>> +loop:
>> + hlt
>> + jmp loop
>>
>> #------------------------------------------------------------------------------
>> # VOID
>> --
>> 1.9.3
>>
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