Re: [PATCH] ArmPlatformPkg/PrePeiCore: seed temporary stack before entering PEI core

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 20 October 2017 at 17:37, Gao, Liming <liming.gao@intel.com> wrote:
> Ard:
>   This case is to share the same value between PeiCore and SecCore. I also think it will be better to define one fixed PCD in MdeModulePkg.dec for this value. Could you submit bugzillar to catch this issue first?
>

Certainly!


>> -----Original Message-----
>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Ard Biesheuvel
>> Sent: Saturday, October 21, 2017 12:10 AM
>> To: Laszlo Ersek <lersek@redhat.com>
>> Cc: edk2-devel@lists.01.org; Leif Lindholm <leif.lindholm@linaro.org>
>> Subject: Re: [edk2] [PATCH] ArmPlatformPkg/PrePeiCore: seed temporary stack before entering PEI core
>>
>> On 20 October 2017 at 16:43, Laszlo Ersek <lersek@redhat.com> wrote:
>> > On 10/20/17 15:00, Leif Lindholm wrote:
>> >> On Fri, Oct 20, 2017 at 12:23:25PM +0100, Ard Biesheuvel wrote:
>> >>> DEBUG builds of PEI code will print a diagnostic message regarding
>> >>> the utilization of temporary RAM before switching to permanent RAM.
>> >>> For example,
>> >>>
>> >>>   Total temporary memory:    16352 bytes.
>> >>>     temporary memory stack ever used:       4820 bytes.
>> >>>     temporary memory heap used for HobList: 4720 bytes.
>> >>>
>> >>> Tracking stack utilization like this requires the stack to be seeded
>> >>> with a known magic value, and this needs to occur before entering C
>> >>> code, given that it uses the stack. Currently, only Nt32Pkg appears
>> >>> to implement this feature, but it is useful nonetheless, so let's
>> >>> wire it up for PrePeiCore.
>> >>>
>> >>> Contributed-under: TianoCore Contribution Agreement 1.1
>> >>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> >>> ---
>> >>>  ArmPlatformPkg/PrePeiCore/AArch64/PrePeiCoreEntryPoint.S |  7 +++++++
>> >>>  ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.S     | 10 ++++++++++
>> >>>  ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.asm   | 10 ++++++++++
>> >>>  3 files changed, 27 insertions(+)
>> >>>
>> >>> diff --git a/ArmPlatformPkg/PrePeiCore/AArch64/PrePeiCoreEntryPoint.S
>> b/ArmPlatformPkg/PrePeiCore/AArch64/PrePeiCoreEntryPoint.S
>> >>> index aab5edab0c42..7a33e2754869 100644
>> >>> --- a/ArmPlatformPkg/PrePeiCore/AArch64/PrePeiCoreEntryPoint.S
>> >>> +++ b/ArmPlatformPkg/PrePeiCore/AArch64/PrePeiCoreEntryPoint.S
>> >>> @@ -13,6 +13,8 @@
>> >>>
>> >>>  #include <AsmMacroIoLibV8.h>
>> >>>
>> >>> +#define INIT_CAR_VALUE      0x5AA55AA55AA55AA5
>> >>> +
>> >>>  ASM_FUNC(_ModuleEntryPoint)
>> >>>    // Do early platform specific actions
>> >>>    bl    ASM_PFX(ArmPlatformPeiBootAction)
>> >>> @@ -84,4 +86,9 @@ _PrepareArguments:
>> >>>
>> >>>  _SetupPrimaryCoreStack:
>> >>>    mov   sp, x1
>> >>> +  MOV64 (x8, FixedPcdGet64(PcdCPUCoresStackBase))
>> >>> +  MOV64 (x9, INIT_CAR_VALUE)
>> >>> +0:stp   x9, x9, [x8], #16
>> >>> +  cmp   x8, x1
>> >>> +  b.lt  0b
>> >>>    b     _PrepareArguments
>> >>> diff --git a/ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.S b/ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.S
>> >>> index 14344425ad4c..7342e49bea59 100644
>> >>> --- a/ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.S
>> >>> +++ b/ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.S
>> >>> @@ -13,6 +13,8 @@
>> >>>
>> >>>  #include <AsmMacroIoLib.h>
>> >>>
>> >>> +#define INIT_CAR_VALUE      0x5AA55AA5
>> >>> +
>> >>
>> >> Worth moving to a common header somewhere?
>> >>
>> >> Also defined/used in MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c.
>> >
>> > Furthermore, open-coded in:
>> >
>> > EmulatorPkg/Unix/Host/Host.c:    *StackPointer = 0x5AA55AA5;
>> > Nt32Pkg/Sec/SecMain.c:    *StackPointer = 0x5AA55AA5;
>> >
>> > Honestly I think it should be a Fixed-At-Build PCD, in MdeModulePkg.dec,
>> > similarly to
>> >
>> >   gEfiMdePkgTokenSpaceGuid.PcdDebugClearMemoryValue
>> >
>> > in MdePkg.dec.
>> >
>>
>> Yes. And you both know how the MdeModulePkg maintainers are going to
>> respond if I propose adding another PCD.
>>
>> > I'm unhappy that we have to annoy Ard with a request to "upstream" this
>> > constant to MdeModulePkg in some form, but we'll need it yet again in
>> > OVMF...
>> >
>>
>>
>> >>
>> >> That file has an explicit comment saying "temporary memory is filled
>> >> with this initial value during SEC phase". Should this end have a
>> >> corresponding comment saying "checked for during PEI phase"?
>> >
>> > Thanks
>> > Laszlo
>> >
>> >>
>> >> /
>> >>     Leif
>> >>
>> >>>  ASM_FUNC(_ModuleEntryPoint)
>> >>>    // Do early platform specific actions
>> >>>    bl    ASM_PFX(ArmPlatformPeiBootAction)
>> >>> @@ -65,6 +67,14 @@ _PrepareArguments:
>> >>>
>> >>>  _SetupPrimaryCoreStack:
>> >>>    mov   sp, r1
>> >>> +  MOV32 (r8, FixedPcdGet64(PcdCPUCoresStackBase))
>> >>> +  MOV32 (r9, INIT_CAR_VALUE)
>> >>> +  mov   r10, r9
>> >>> +  mov   r11, r9
>> >>> +  mov   r12, r9
>> >>> +0:stm   r8!, {r9-r12}
>> >>> +  cmp   r8, r1
>> >>> +  blt   0b
>> >>>    b     _PrepareArguments
>> >>>
>> >>>  _NeverReturn:
>> >>> diff --git a/ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.asm
>> b/ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.asm
>> >>> index abea675828df..7455de8aa66e 100644
>> >>> --- a/ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.asm
>> >>> +++ b/ArmPlatformPkg/PrePeiCore/Arm/PrePeiCoreEntryPoint.asm
>> >>> @@ -13,6 +13,8 @@
>> >>>
>> >>>  #include <AutoGen.h>
>> >>>
>> >>> +#define INIT_CAR_VALUE      0x5AA55AA5
>> >>> +
>> >>>    INCLUDE AsmMacroIoLib.inc
>> >>>
>> >>>    IMPORT  CEntryPoint
>> >>> @@ -79,6 +81,14 @@ _PrepareArguments
>> >>>
>> >>>  _SetupPrimaryCoreStack
>> >>>    mov   sp, r1
>> >>> +  mov32 r8, FixedPcdGet64(PcdCPUCoresStackBase)
>> >>> +  mov32 r9, INIT_CAR_VALUE
>> >>> +  mov   r10, r9
>> >>> +  mov   r11, r9
>> >>> +  mov   r12, r9
>> >>> +0:stm   r8!, {r9-r12}
>> >>> +  cmp   r8, r1
>> >>> +  blt   0b
>> >>>    b     _PrepareArguments
>> >>>
>> >>>  _NeverReturn
>> >>> --
>> >>> 2.11.0
>> >>>
>> >
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