On 31. Mar 2023, at 16:41, Ni, Ray <ray.ni@intel.com> wrote:
Why ELF header overflows into .text section?
That's a good question, isn't it? :)
From what I can see, these binaries don't pass post-processing like GenFw or such. GCC (and I think thus CLANGDWARF?) gets an extra objcopy step as part of linking [2], but the arguments are empty [3] and thus should be no-op (I hope?).
I suppose potential candidates are:
1) A bug in the LLD linker used by CLANGDWARF for IA32 and X64. That would be very surprising to me, especially as no other platform reported issues and LLD is well-established. But who knows, generally ELFs will have large alignment values compared to the 64 Bytes used by edk2.
2) A bug in llvm-objcopy used by UniversalPayloadBuild.py [1]. I'm honestly unfamiliar with objcopy variants and their quality/reliability.
3) A bug in the llvm-objcopy or CLANGDWARF tools_def commands on the edk2 side of things.
Some may disagree, but I would reduce 3) to either 1) or 2). I think even if the commands malformed and this causes the overflow, I believe LLD or objcopy should issue a warning regardless.
As I have no way to reproduce the issue, I cannot really help further, sorry.
Best regards,
Marvin
[1]
[2]
[3]
-----Original Message-----
From: Patrick Rudolph <patrick.rudolph@9elements.com>
Sent: Friday, March 17, 2023 10:06 PM
Cc: devel@edk2.groups.io; Dong, Guo <guo.dong@intel.com>; Guo, Gua
<gua.guo@intel.com>; Lu, James <james.lu@intel.com>; Ni, Ray
<ray.ni@intel.com>; mhaeuser@posteo.de; ardb@kernel.org
Subject: [PATCH 2/3] BaseTools/Conf/tools_def: Fix
CLANGDWARF_IA32_X64
Drop the "-z max-page-size=0x40" option as it causes the ELF
header to overflow into the .text section, causing undefined
behaviour.
With high optimization level it corrupts essential code and
the binary would crash. It might work with low optimization
level though. As the default is to use Oz and LTO, it always
crashes.
Test:
The ELF generated by
'python UefiPayloadPkg/UniversalPayloadBuild.py -a IA32' boots.
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=4357
---
BaseTools/Conf/tools_def.template | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/BaseTools/Conf/tools_def.template
b/BaseTools/Conf/tools_def.template
index 9b59bd75c3..0c584ab390 100755
--- a/BaseTools/Conf/tools_def.template
+++ b/BaseTools/Conf/tools_def.template
@@ -2866,7 +2866,7 @@ DEFINE CLANGDWARF_X64_PREFIX =
ENV(CLANG_BIN)
# LLVM/CLANG doesn't support -n link option. So, it can't share the same
IA32_X64_DLINK_COMMON flag.
# LLVM/CLANG doesn't support common page size. So, it can't share the
same GccBase.lds script.
-DEFINE CLANGDWARF_IA32_X64_DLINK_COMMON = -nostdlib -Wl,-q,--gc-
sections -z max-page-size=0x40
+DEFINE CLANGDWARF_IA32_X64_DLINK_COMMON = -nostdlib -Wl,-q,--
gc-sections
DEFINE CLANGDWARF_DLINK2_FLAGS_COMMON = -Wl,--
script=$(EDK_TOOLS_PATH)/Scripts/ClangBase.lds
DEFINE CLANGDWARF_IA32_X64_ASLDLINK_FLAGS =
DEF(CLANGDWARF_IA32_X64_DLINK_COMMON) -Wl,--
defsym=PECOFF_HEADER_SIZE=0
DEF(CLANGDWARF_DLINK2_FLAGS_COMMON) -Wl,--
entry,ReferenceAcpiTable -u ReferenceAcpiTable
DEFINE CLANGDWARF_IA32_X64_DLINK_FLAGS =
DEF(CLANGDWARF_IA32_X64_DLINK_COMMON) -Wl,--
entry,$(IMAGE_ENTRY_POINT) -u $(IMAGE_ENTRY_POINT) -Wl,-
Map,$(DEST_DIR_DEBUG)/$(BASE_NAME).map,--whole-archive
--
2.39.1