Test that the _r_debug list looks OK
Match it against the dl_iterate_phdr list. It should have the same entries,
but they could be in a different order.
Test that the dl_iterate_phdr callback always provides at least a PT_LOAD
segment.
Verify that the executable comes first in the _r_debug list.
Test: bionic-unit-tests
Bug: http://b/110967431
Change-Id: I9b6ec77d1205c4c45848adf65456bb7b3da4a3a1
diff --git a/tests/link_test.cpp b/tests/link_test.cpp
index a5430a9..1bdee9f 100644
--- a/tests/link_test.cpp
+++ b/tests/link_test.cpp
@@ -29,6 +29,12 @@
#include <gtest/gtest.h>
#include <link.h>
+#if __has_include(<sys/auxv.h>)
+#include <sys/auxv.h>
+#endif
+
+#include <string>
+#include <unordered_map>
TEST(link, dl_iterate_phdr_early_exit) {
static size_t call_count = 0;
@@ -40,7 +46,7 @@
TEST(link, dl_iterate_phdr) {
struct Functor {
static int Callback(dl_phdr_info* i, size_t s, void* data) {
- reinterpret_cast<Functor*>(data)->DoChecks(i, s);
+ static_cast<Functor*>(data)->DoChecks(i, s);
return 0;
}
void DoChecks(dl_phdr_info* info, size_t s) {
@@ -48,7 +54,12 @@
ASSERT_TRUE(info->dlpi_name != nullptr);
+ // An ELF file must have at least a PT_LOAD program header.
+ ASSERT_NE(nullptr, info->dlpi_phdr);
+ ASSERT_NE(0, info->dlpi_phnum);
+
// Find the first PT_LOAD program header so we can find the ELF header.
+ bool found_load = false;
for (ElfW(Half) i = 0; i < info->dlpi_phnum; ++i) {
const ElfW(Phdr)* phdr = reinterpret_cast<const ElfW(Phdr)*>(&info->dlpi_phdr[i]);
if (phdr->p_type == PT_LOAD) {
@@ -58,15 +69,124 @@
ASSERT_EQ(0, memcmp(ehdr, ELFMAG, SELFMAG));
// Does the e_phnum match what dl_iterate_phdr told us?
ASSERT_EQ(info->dlpi_phnum, ehdr->e_phnum);
+ found_load = true;
break;
}
}
+ ASSERT_EQ(true, found_load);
}
size_t count;
} f = {};
ASSERT_EQ(0, dl_iterate_phdr(Functor::Callback, &f));
}
+struct ProgHdr {
+ const ElfW(Phdr)* table;
+ size_t size;
+};
+
+__attribute__((__unused__))
+static ElfW(Addr) find_exe_load_bias(const ProgHdr& phdr) {
+ for (size_t i = 0; i < phdr.size; ++i) {
+ if (phdr.table[i].p_type == PT_PHDR) {
+ return reinterpret_cast<ElfW(Addr)>(phdr.table) - phdr.table[i].p_vaddr;
+ }
+ }
+ return 0;
+}
+
+__attribute__((__unused__))
+static ElfW(Dyn)* find_dynamic(const ProgHdr& phdr, ElfW(Addr) load_bias) {
+ for (size_t i = 0; i < phdr.size; ++i) {
+ if (phdr.table[i].p_type == PT_DYNAMIC) {
+ return reinterpret_cast<ElfW(Dyn)*>(phdr.table[i].p_vaddr + load_bias);
+ }
+ }
+ return nullptr;
+}
+
+__attribute__((__unused__))
+static r_debug* find_exe_r_debug(ElfW(Dyn)* dynamic) {
+ for (ElfW(Dyn)* d = dynamic; d->d_tag != DT_NULL; ++d) {
+ if (d->d_tag == DT_DEBUG) {
+ return reinterpret_cast<r_debug*>(d->d_un.d_val);
+ }
+ }
+ return nullptr;
+}
+
+// Walk the DT_DEBUG/_r_debug global module list and compare it with the same
+// information from dl_iterate_phdr. Verify that the executable appears first
+// in _r_debug.
+TEST(link, r_debug) {
+#if __has_include(<sys/auxv.h>)
+ // Find the executable's PT_DYNAMIC segment and DT_DEBUG value. The linker
+ // will write the address of its _r_debug global into the .dynamic section.
+ ProgHdr exe_phdr = {
+ .table = reinterpret_cast<ElfW(Phdr)*>(getauxval(AT_PHDR)),
+ .size = getauxval(AT_PHNUM)
+ };
+ ASSERT_NE(nullptr, exe_phdr.table);
+ ElfW(Addr) exe_load_bias = find_exe_load_bias(exe_phdr);
+ ASSERT_NE(0u, exe_load_bias);
+ ElfW(Dyn)* exe_dynamic = find_dynamic(exe_phdr, exe_load_bias);
+ ASSERT_NE(nullptr, exe_dynamic);
+ r_debug* dbg = find_exe_r_debug(exe_dynamic);
+ ASSERT_NE(nullptr, dbg);
+
+ // Use dl_iterate_phdr to build a table mapping from load bias values to
+ // solib names and PT_DYNAMIC segments.
+ struct DlIterateInfo {
+ std::string name;
+ ElfW(Dyn)* dynamic;
+ };
+ struct Functor {
+ std::unordered_map<ElfW(Addr), DlIterateInfo> dl_iter_mods;
+ static int Callback(dl_phdr_info* i, size_t s, void* data) {
+ static_cast<Functor*>(data)->AddModule(i, s);
+ return 0;
+ }
+ void AddModule(dl_phdr_info* info, size_t s) {
+ ASSERT_EQ(sizeof(dl_phdr_info), s);
+ ASSERT_TRUE(dl_iter_mods.find(info->dlpi_addr) == dl_iter_mods.end());
+ ASSERT_TRUE(info->dlpi_name != nullptr);
+ dl_iter_mods[info->dlpi_addr] = {
+ .name = info->dlpi_name,
+ .dynamic = find_dynamic({ info->dlpi_phdr, info->dlpi_phnum }, info->dlpi_addr)
+ };
+ }
+ } f = {};
+ ASSERT_EQ(0, dl_iterate_phdr(Functor::Callback, &f));
+
+ size_t map_size = 0;
+
+ for (link_map* map = dbg->r_map; map != nullptr; map = map->l_next) {
+ ASSERT_NE(0u, map->l_addr);
+ ASSERT_NE(nullptr, map->l_ld);
+ ASSERT_NE(nullptr, map->l_name);
+
+ auto it = f.dl_iter_mods.find(map->l_addr);
+ ASSERT_TRUE(it != f.dl_iter_mods.end());
+ const DlIterateInfo& info = it->second;
+ ASSERT_EQ(info.name, map->l_name);
+ ASSERT_EQ(info.dynamic, map->l_ld);
+
+ ++map_size;
+ }
+
+ // _r_debug and dl_iterate_phdr should report the same set of modules. We
+ // verified above that every _r_debug module was reported by dl_iterate_phdr,
+ // so checking the sizes verifies the converse.
+ ASSERT_EQ(f.dl_iter_mods.size(), map_size);
+
+ // Make sure the first entry is the executable. gdbserver assumes this and
+ // removes the first entry from its list of shared objects that it sends back
+ // to gdb.
+ ASSERT_EQ(exe_load_bias, dbg->r_map->l_addr);
+ ASSERT_EQ(exe_dynamic, dbg->r_map->l_ld);
+#endif
+}
+
#if __arm__
static uintptr_t read_exidx_func(uintptr_t* entry) {
int32_t offset = *entry;