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Bug 1412405 - fix isnanf symbol lookup by using a LoadedElf for libm; r=glandium

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We already dealt with issues around dlsym not resolving weak symbols
with libc in bug 1081034.  This fix applies the same workaround to libm,
which solves the isnanf issue.

The previous fix for looking up __isnanf is no longer needed.
This commit is contained in:
Nathan Froyd 2017-10-28 08:51:23 -04:00
parent ebf6afd3a0
commit c04d322a0a
2 changed files with 8 additions and 19 deletions
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24
mozglue/linker/ElfLoader.cpp
View File

@ -20,6 +20,7 @@
#if defined(ANDROID)
#include <sys/syscall.h>
#include <math.h>
#include <android/api-level.h>
#if __ANDROID_API__ < 8
@ -331,25 +332,6 @@ void *
SystemElf::GetSymbolPtr(const char *symbol) const
{
void *sym = dlsym(dlhandle, symbol);
// Various bits of Gecko use isnanf, which gcc is happy to compile into
// inlined code using floating-point comparisons. clang, on the other hand,
// does not use inline code and generates full calls to isnanf.
//
// libm.so on Android defines isnanf as weak. dlsym always returns null for
// weak symbols. Which means that we'll never be able to resolve the symbol
// that clang generates here. However, said weak symbol for isnanf is just
// an alias for __isnanf, which is the real definition. So if we're asked
// for isnanf and we can't find it, try looking for __isnanf instead. The
// actual system linker uses alternate resolution interfaces and therefore
// does not encounter this issue.
//
// See also https://bugs.chromium.org/p/chromium/issues/detail?id=376828,
// from which this comment and this fix are adapted.
if (!sym &&
!strcmp(symbol, "isnanf") &&
!strcmp(GetName(), "libm.so")) {
sym = dlsym(dlhandle, "__isnanf");
}
DEBUG_LOG("dlsym(%p [\"%s\"], \"%s\") = %p", dlhandle, GetPath(), symbol, sym);
ElfLoader::Singleton.lastError = dlerror();
return sym;
@ -576,6 +558,9 @@ ElfLoader::Init()
if (dladdr(FunctionPtr(syscall), &info) != 0) {
libc = LoadedElf::Create(info.dli_fname, info.dli_fbase);
}
if (dladdr(FunctionPtr<int (*)(double)>(isnan), &info) != 0) {
libm = LoadedElf::Create(info.dli_fname, info.dli_fbase);
}
#endif
}
@ -591,6 +576,7 @@ ElfLoader::~ElfLoader()
self_elf = nullptr;
#if defined(ANDROID)
libc = nullptr;
libm = nullptr;
#endif
AutoLock lock(&handlesMutex);

3
mozglue/linker/ElfLoader.h
View File

@ -473,6 +473,9 @@ private:
* we wouldn't treat non-Android differently, but glibc uses versioned
* symbols which this linker doesn't support. */
RefPtr<LibHandle> libc;
/* And for libm. */
RefPtr<LibHandle> libm;
#endif
/* Bookkeeping */