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[BOLT][Linux] Fix linux_banner lookup #144962

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Merged
merged 1 commit into from
Jun 20, 2025
Merged

[BOLT][Linux] Fix linux_banner lookup #144962

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42 changes: 25 additions & 17 deletions bolt/lib/Rewrite/LinuxKernelRewriter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -432,25 +432,33 @@ class LinuxKernelRewriter final : public MetadataRewriter {
};

Error LinuxKernelRewriter::detectLinuxKernelVersion() {
if (BinaryData *BD = BC.getBinaryDataByName("linux_banner")) {
const BinarySection &Section = BD->getSection();
const std::string S =
Section.getContents().substr(BD->getOffset(), BD->getSize()).str();

const std::regex Re(R"---(Linux version ((\d+)\.(\d+)(\.(\d+))?))---");
std::smatch Match;
if (std::regex_search(S, Match, Re)) {
const unsigned Major = std::stoi(Match[2].str());
const unsigned Minor = std::stoi(Match[3].str());
const unsigned Rev = Match[5].matched ? std::stoi(Match[5].str()) : 0;
LinuxKernelVersion = LKVersion(Major, Minor, Rev);
BC.outs() << "BOLT-INFO: Linux kernel version is " << Match[1].str()
<< "\n";
return Error::success();
}
// Check for global and local linux_banner symbol.
BinaryData *BD = BC.getBinaryDataByName("linux_banner");
if (!BD)
BD = BC.getBinaryDataByName("linux_banner/1");

if (!BD)
return createStringError(errc::executable_format_error,
"unable to locate linux_banner");

const BinarySection &Section = BD->getSection();
const std::string S =
Section.getContents().substr(BD->getOffset(), BD->getSize()).str();

const std::regex Re(R"---(Linux version ((\d+)\.(\d+)(\.(\d+))?))---");
std::smatch Match;
if (std::regex_search(S, Match, Re)) {
const unsigned Major = std::stoi(Match[2].str());
const unsigned Minor = std::stoi(Match[3].str());
const unsigned Rev = Match[5].matched ? std::stoi(Match[5].str()) : 0;
LinuxKernelVersion = LKVersion(Major, Minor, Rev);
BC.outs() << "BOLT-INFO: Linux kernel version is " << Match[1].str()
<< "\n";
return Error::success();
}

return createStringError(errc::executable_format_error,
"Linux kernel version is unknown");
"Linux kernel version is unknown: " + S);
}

void LinuxKernelRewriter::processLKSections() {
Expand Down
11 changes: 11 additions & 0 deletions bolt/test/X86/linux-version.S
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,11 @@
# RUN: -Wl,--image-base=0xffffffff80000000,--no-dynamic-linker,--no-eh-frame-hdr
# RUN: llvm-bolt %t.exe -o %t.out 2>&1 | FileCheck --check-prefix=CHECK-C %s

# RUN: %clang -DD -target x86_64-unknown-unknown \
# RUN: %cflags -nostdlib %s -o %t.exe \
# RUN: -Wl,--image-base=0xffffffff80000000,--no-dynamic-linker,--no-eh-frame-hdr
# RUN: llvm-bolt %t.exe -o %t.out 2>&1 | FileCheck --check-prefix=CHECK-D %s

.text
.globl foo
.type foo, %function
Expand Down Expand Up @@ -46,6 +51,12 @@ linux_banner:
#endif
# CHECK-C: BOLT-INFO: Linux kernel version is 6.6

#ifdef D
.hidden linux_banner
.string "Linux version 6.6.15.2-2-xxx\n"
#endif
# CHECK-D: BOLT-INFO: Linux kernel version is 6.6

.size linux_banner, . - linux_banner

## Fake Linux Kernel sections.
Expand Down
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