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LibC+LibELF: Implement support for the dl_iterate_phdr helper

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This helper is used by libgcc_s to figure out where the .eh_frame sections
are located for all loaded shared objects.
This commit is contained in:
Gunnar Beutner 2021-04-16 21:53:43 +02:00 • committed by Andreas Kling
parent cf13fa57cd
commit 6cb28ecee8
20 changed files with 171 additions and 25 deletions
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25
Userland/Libraries/LibELF/DynamicLinker.cpp
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@ -32,6 +32,7 @@
#include <AK/LexicalPath.h>
#include <AK/NonnullRefPtrVector.h>
#include <AK/ScopeGuard.h>
#include <LibC/link.h>
#include <LibC/mman.h>
#include <LibC/unistd.h>
#include <LibELF/AuxiliaryVector.h>
@ -52,6 +53,8 @@ Vector<NonnullRefPtr<ELF::DynamicObject>> g_global_objects;
using EntryPointFunction = int (*)(int, char**, char**);
using LibCExitFunction = void (*)(int);
using DlIteratePhdrCallbackFunction = int (*)(struct dl_phdr_info*, size_t, void*);
using DlIteratePhdrFunction = int (*)(DlIteratePhdrCallbackFunction, void*);
size_t g_current_tls_offset = 0;
size_t g_total_tls_size = 0;
@ -162,6 +165,24 @@ static void allocate_tls()
g_total_tls_size = total_tls_size;
}
static int __dl_iterate_phdr(DlIteratePhdrCallbackFunction callback, void* data)
{
for (auto& object : g_global_objects) {
auto info = dl_phdr_info {
.dlpi_addr = (ElfW(Addr))object->base_address().as_ptr(),
.dlpi_name = object->filename().characters(),
.dlpi_phdr = object->program_headers(),
.dlpi_phnum = object->program_header_count()
};
auto res = callback(&info, sizeof(info), data);
if (res != 0)
return res;
}
return 0;
}
static void initialize_libc(DynamicObject& libc)
{
// Traditionally, `_start` of the main program initializes libc.
@ -181,6 +202,10 @@ static void initialize_libc(DynamicObject& libc)
VERIFY(res.has_value());
g_libc_exit = (LibCExitFunction)res.value().address.as_ptr();
res = libc.lookup_symbol("__dl_iterate_phdr"sv);
VERIFY(res.has_value());
*((DlIteratePhdrFunction*)res.value().address.as_ptr()) = __dl_iterate_phdr;
res = libc.lookup_symbol("__libc_init"sv);
VERIFY(res.has_value());
typedef void libc_init_func();