Magic-Mirror/llvm-capstone
1
0
Fork 0
mirror of https://github.com/capstone-engine/llvm-capstone.git synced 2024-11-23 05:40:09 +00:00
Code Issues Actions 2 Packages Projects Releases Wiki Activity

[libc] support PIE relocations (#78993)

Browse Source 
For some reasons, we are using `-fpie`
(libc/cmake/modules/LLVMLibCObjectRules.cmake:31) without supporting it.
According to @lntue, some of the hermetic tests are broken without
proper PIE support. This patch implements basic relocations support for
PIE.
This commit is contained in:
Schrodinger ZHU Yifan 2024-01-22 12:45:35 -05:00 committed by GitHub
parent 02f95b7751
commit 0fe20aa45e
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
1 changed files with 21 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
libc/startup/linux/do_start.cpp
View File

@ -29,6 +29,11 @@ extern uintptr_t __init_array_start[];
extern uintptr_t __init_array_end[];
extern uintptr_t __fini_array_start[];
extern uintptr_t __fini_array_end[];
// https://refspecs.linuxbase.org/elf/gabi4+/ch5.dynamic.html#dynamic_section
// This symbol is provided by the dynamic linker. It can be undefined depending
// on how the program is loaded exactly.
[[gnu::weak,
gnu::visibility("hidden")]] extern const Elf64_Dyn _DYNAMIC[]; // NOLINT
}
namespace LIBC_NAMESPACE {
@ -94,18 +99,26 @@ static ThreadAttributes main_thread_attrib;
}
}
ptrdiff_t base = 0;
app.tls.size = 0;
Elf64_Phdr *tls_phdr = nullptr;
for (uintptr_t i = 0; i < program_hdr_count; ++i) {
Elf64_Phdr *phdr = program_hdr_table + i;
if (phdr->p_type != PT_TLS)
continue;
// TODO: p_vaddr value has to be adjusted for static-pie executables.
app.tls.address = phdr->p_vaddr;
app.tls.size = phdr->p_memsz;
app.tls.init_size = phdr->p_filesz;
app.tls.align = phdr->p_align;
Elf64_Phdr &phdr = program_hdr_table[i];
if (phdr.p_type == PT_PHDR)
base = reinterpret_cast<ptrdiff_t>(program_hdr_table) - phdr.p_vaddr;
if (phdr.p_type == PT_DYNAMIC && _DYNAMIC)
base = reinterpret_cast<ptrdiff_t>(_DYNAMIC) - phdr.p_vaddr;
if (phdr.p_type == PT_TLS)
tls_phdr = &phdr;
// TODO: adjust PT_GNU_STACK
}
app.tls.address = tls_phdr->p_vaddr + base;
app.tls.size = tls_phdr->p_memsz;
app.tls.init_size = tls_phdr->p_filesz;
app.tls.align = tls_phdr->p_align;
// This descriptor has to be static since its cleanup function cannot
// capture the context.
static TLSDescriptor tls;