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linker: remove COUNT_PAGES 

COUNT_PAGES tries to count the pages dirtied by relocations, but this
implementation is broken because it's merging rel->r_offset values from
multiple DSOs. The functionality is hard to use, because it requires
rebuilding the linker, and it's not obvious to me that it should belong
in the linker. If we do want it, we should make it work without rebuilding
the linker.

Similar information can currently be collected by parsing the result of
`readelf -r` on a binary (or a set of binaries).

Bug: none
Test: m linker libc com.android.runtime ; adb sync ; run something
Change-Id: I760fb6ea4ea3d1927eb5145cdf4ca133851d69b4
This commit is contained in:
Ryan Prichard 2019-10-25 17:46:43 -07:00
parent 04f27f23dc
commit 78cd283480
3 changed files with 1 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
linker/linker.cpp
View File

@ -300,10 +300,6 @@ void count_relocation(RelocationKind) {
}
#endif
#if COUNT_PAGES
uint32_t bitmask[4096];
#endif
static void notify_gdb_of_load(soinfo* info) {
if (info->is_linker() || info->is_main_executable()) {
// gdb already knows about the linker and the main executable.
@ -3141,7 +3137,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
switch (type) {
case R_GENERIC_JUMP_SLOT:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO JMP_SLOT %16p <- %16p %s\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(sym_addr + addend), sym_name);
@ -3151,7 +3146,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
case R_GENERIC_ABSOLUTE:
case R_GENERIC_GLOB_DAT:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO ABSOLUTE/GLOB_DAT %16p <- %16p %s\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(sym_addr + addend), sym_name);
@ -3159,7 +3153,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
break;
case R_GENERIC_RELATIVE:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO RELATIVE %16p <- %16p\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(load_bias + addend));
@ -3167,7 +3160,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
break;
case R_GENERIC_IRELATIVE:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO IRELATIVE %16p <- %16p\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(load_bias + addend));
@ -3211,7 +3203,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
return false;
case R_GENERIC_TLS_TPREL:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
{
ElfW(Addr) tpoff = 0;
if (lsi == nullptr) {
@ -3237,7 +3228,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
break;
case R_GENERIC_TLS_DTPMOD:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
{
size_t module_id = 0;
if (lsi == nullptr) {
@ -3253,7 +3243,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
break;
case R_GENERIC_TLS_DTPREL:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO TLS_DTPREL %16p <- %16p %s\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(sym_addr + addend), sym_name);
@ -3265,7 +3254,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
// other architectures, as long as the resolver functions are implemented.
case R_GENERIC_TLSDESC:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
{
TlsDescriptor* desc = reinterpret_cast<TlsDescriptor*>(reloc);
if (lsi == nullptr) {
@ -3306,14 +3294,12 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
#if defined(__x86_64__)
case R_X86_64_32:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO R_X86_64_32 %08zx <- +%08zx %s", static_cast<size_t>(reloc),
static_cast<size_t>(sym_addr), sym_name);
*reinterpret_cast<Elf32_Addr*>(reloc) = sym_addr + addend;
break;
case R_X86_64_PC32:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO R_X86_64_PC32 %08zx <- +%08zx (%08zx - %08zx) %s",
static_cast<size_t>(reloc), static_cast<size_t>(sym_addr - reloc),
static_cast<size_t>(sym_addr), static_cast<size_t>(reloc), sym_name);
@ -3322,7 +3308,6 @@ bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& r
#elif defined(__i386__)
case R_386_PC32:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO R_386_PC32 %08x <- +%08x (%08x - %08x) %s",
reloc, (sym_addr - reloc), sym_addr, reloc, sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr - reloc);

20
linker/linker_debug.h
View File

@ -44,7 +44,6 @@
#define DO_TRACE_IFUNC 1
#define TIMING 0
#define STATS 0
#define COUNT_PAGES 0
/*********************************************************************
* You shouldn't need to modify anything below unless you are adding
@ -83,22 +82,3 @@ __LIBC_HIDDEN__ extern int g_ld_debug_verbosity;
#endif /* TRACE_DEBUG */
#define TRACE_TYPE(t, x...) do { if (DO_TRACE_##t) { TRACE(x); } } while (0)
#if COUNT_PAGES
extern uint32_t bitmask[];
#if defined(__LP64__)
#define MARK(offset) \
do { \
if ((((offset) >> 12) >> 5) < 4096) \
bitmask[((offset) >> 12) >> 5] |= (1 << (((offset) >> 12) & 31)); \
} while (0)
#else
#define MARK(offset) \
do { \
bitmask[((offset) >> 12) >> 3] |= (1 << (((offset) >> 12) & 7)); \
} while (0)
#endif
#else
#define MARK(x) do {} while (0)
#endif

26
linker/linker_main.cpp
View File

@ -496,31 +496,7 @@ static ElfW(Addr) linker_main(KernelArgumentBlock& args, const char* exe_to_load
#if STATS
print_linker_stats();
#endif
#if COUNT_PAGES
{
unsigned n;
unsigned i;
unsigned count = 0;
for (n = 0; n < 4096; n++) {
if (bitmask[n]) {
unsigned x = bitmask[n];
#if defined(__LP64__)
for (i = 0; i < 32; i++) {
#else
for (i = 0; i < 8; i++) {
#endif
if (x & 1) {
count++;
}
x >>= 1;
}
}
}
PRINT("PAGES MODIFIED: %s: %d (%dKB)", g_argv[0], count, count * 4);
}
#endif
#if TIMING || STATS || COUNT_PAGES
#if TIMING || STATS
fflush(stdout);
#endif