On 1 August 2016 at 16:18, Gao, Liming <[email protected]> wrote:
> Ard:
> I don't think it is good way to define GCC_VISIBILITY_PROTECTED and apply
> it in EntryPointLib. We only need to expose _ModuleEntryPoint. It has been
> specified in LINK_FLAGS in tools_def.txt. Could we also specify its attribute
> in CC_FLAGS or LINK_FLAGS in tools_def.txt?
>
It seems this does the trick as well
diff --git a/BaseTools/Scripts/GccBase.lds b/BaseTools/Scripts/GccBase.lds
index 281af8a9bd33..02387d4f8d6f 100644
--- a/BaseTools/Scripts/GccBase.lds
+++ b/BaseTools/Scripts/GccBase.lds
@@ -80,3 +80,7 @@ SECTIONS {
*(COMMON)
}
}
+
+VERSION {
+ { global: _ModuleEntryPoint*; };
+};
Note that * at the end: this is necessary since _ModuleEntryPoint will
be called _ModuleEntryPoint.lto_priv.xxx in the LTO objects.
I will drop this patch, and add this hunk to GccBase.lds instead.
--
Ard.
> Thanks
> Liming
>> -----Original Message-----
>> From: edk2-devel [mailto:[email protected]] On Behalf Of
>> Ard Biesheuvel
>> Sent: Monday, August 01, 2016 4:02 PM
>> To: Shi, Steven ; Zhu, Yonghong
>> ; Gao, Liming ; Justen,
>> Jordan L ; [email protected]
>> Cc: [email protected]; [email protected]; Ard Biesheuvel
>>
>> Subject: [edk2] [PATCH v5 7/8] MdePkg GCC/X64: avoid 'hidden' visibility for
>> module entry points
>>
>> When building with LTO enabled, the LTO routines infer from the 'hidden'
>> visibility of the _ModuleEntryPoint symbol that its code only needs to be
>> retained if it is referenced internally, and disregards the fact that
>> it is referenced by the entry point field in the ELF metadata.
>>
>> This is arguably a bug in LTO, but we can work around it by ensuring that
>> the _ModuleEntryPoint symbol is emitted with protected visibility instead.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.0
>> Signed-off-by: Ard Biesheuvel
>> ---
>> MdePkg/Include/X64/ProcessorBind.h | 9 ++++++++-
>> MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf | 2 ++
>> MdePkg/Library/PeiCoreEntryPoint/PeiCoreEntryPoint.inf | 2 ++
>> MdePkg/Library/PeimEntryPoint/PeimEntryPoint.inf | 2 ++
>> MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf | 2
>> ++
>> MdePkg/Library/UefiDriverEntryPoint/UefiDriverEntryPoint.inf | 2 ++
>> 6 files changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/MdePkg/Include/X64/ProcessorBind.h
>> b/MdePkg/Include/X64/ProcessorBind.h
>> index 666cc8e8bd16..e45b9cba2bb3 100644
>> --- a/MdePkg/Include/X64/ProcessorBind.h
>> +++ b/MdePkg/Include/X64/ProcessorBind.h
>> @@ -29,13 +29,20 @@
>>
>> #if defined(__GNUC__) && defined(__pic__)
>> //
>> -// Mark all symbol declarations and references as hidden, meaning they will
>> +// Mark all symbol declarations and references as hidden*, meaning they
>> will
>> // not be subject to symbol preemption. This allows the compiler to refer to
>> // symbols directly using relative references rather than via the GOT, which
>> // contains absolute symbol addresses that are subject to runtime relocation.
>> //
>> +// * Under LTO, the entry point of a module must have protected or default
>> +// visibility to prevent it from being pruned.
>> +//
>> +#ifdef GCC_VISIBILITY_PROTECTED
>> +#pragma GCC visibility push (protected)
>> +#else
>> #pragma GCC visibility push (hidden)
>> #endif
>> +#endif
>>
>> #if defined(__INTEL_COMPILER)
>> //
>> diff --git a/MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> b/MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> index 01f64c34c7a1..2d6f87ed062e 100644
>> --- a/MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> +++ b/MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> @@ -39,3 +39,5 @@ [LibraryClasses]
>> BaseLib
>> DebugLib
>>
>> +[BuildOptions]
>> + GCC:*_*_X64_CC_FLAGS = -DGCC_VISIBILITY_PROTECTED
>> diff --git a/MdePkg/Library/PeiCoreEntryPoint/PeiCoreEntryPoint.inf
>> b/MdePkg/Library/PeiCoreEntryPoint/PeiCoreEntryPoint.inf
>> index d920306713c5..4e61783b3bd5 100644
>> --- a/MdePkg/Library/PeiCoreEntryPoint/PeiCoreEntryPoint.inf
>> +++ b/MdePkg/Library/PeiCoreEntryPoint/PeiCoreEntryPoint.inf
>> @@ -37,3 +37,5 @@ [LibraryClasses]
>> BaseLib
>> DebugLib
>>
>> +[BuildOptions]
>> + GCC:*_*_X64_CC_FLAGS = -DGCC_VISIBILITY_PROTECTED
>> diff --git a/MdePkg/Library/PeimEntryPoint/PeimEntryPoint.inf
>> b/MdePkg/Library/PeimEntryPoint/PeimEntryPoint.inf
>> index a2db9e058bbe..adfd91bdc57e 100644
>> --- a/MdePkg/Library/PeimEntryPoint/PeimEntryPoint.inf
>> +++ b/MdePkg/Library/PeimEntryPoint/PeimEntryPoint.inf
>> @@ -37,3 +37,5 @@ [Packages]
>> [LibraryClasses]
>> DebugLib
>>
>> +[BuildOptions]
>> + GCC:*_*_X64_CC_FLAGS = -DGCC_VISIBILITY_PROTECTED
>> diff --git
>> a/MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf
>> b/MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf
>> index be92b3dc0760..9525c55c2051 100644
>> ---
>> a/MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf
>> +++
>> b/MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf
>> @@ -38,3 +38,5 @@ [LibraryClasses]
>> DebugLib
>> BaseLib
>>
>> +[BuildOptions]
>> + GCC:*_*_X64_CC_FLAGS = -DGCC_VISIBILITY_PROTECTED
>> diff --git a/MdePkg/Library/UefiDriverEntryPoint/UefiDriverEntryPoint.inf
>> b/MdePkg/Library/UefiDriverEntryPoint/UefiDriverEntryPoint.inf
>> index 7a9dcbcd4df2..8d30b1197850 100644
>> --- a/MdePkg/Library/UefiDriverEntryPoint/UefiDriverEntryPoint.inf
>> +++ b/MdePkg/Library/UefiDriverEntryPoint/UefiDriverEntryPoint.inf
>> @@ -65,3 +65,5 @@ [Depex.common.UEFI_DRIVER]
>> gEfiVariableArchProtocolGuid AND
>> gEfiWatchdogTimerArchProtocolGuid
>>
>> +[BuildOptions]
>> + GCC:*_*_X64_CC_FLAGS = -DGCC_VISIBILITY_PROTECTED
>> --
>> 2.7.4
>>
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>> edk2-devel mailing list
>> [email protected]
>> https://lists.01.org/mailman/listinfo/edk2-devel
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