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Revisiting auxvec data gathering for PPC/ARM.

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/proc/sys/auxv might not be accessible, instead
getting these from the user's stack.

Change-Id: I2dcf696734e2b4dc1da27a991930b9e0d4228d51
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1730990
Commit-Queue: Clemens Backes [né Hammacher] <clemensb@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Clemens Backes [né Hammacher] <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64037}
This commit is contained in:
David Carlier 2019-09-26 18:40:08 +01:00 committed by Commit Bot
parent 3a8baab584
commit f5bee00274
1 changed files with 33 additions and 40 deletions
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73
src/base/cpu.cc
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@ -9,6 +9,7 @@
#endif
#if V8_OS_LINUX
#include <linux/auxvec.h> // AT_HWCAP
extern "C" char** environ;
#endif
#if V8_GLIBC_PREREQ(2, 16)
#include <sys/auxv.h> // getauxval()
@ -16,7 +17,7 @@
#if V8_OS_QNX
#include <sys/syspage.h> // cpuinfo
#endif
#if V8_OS_LINUX && V8_HOST_ARCH_PPC
#if (V8_OS_LINUX && V8_HOST_ARCH_PPC) || V8_OS_ANDROID
#include <elf.h>
#endif
#if V8_OS_AIX
@ -109,28 +110,25 @@ static V8_INLINE void __cpuid(int cpu_info[4], int info_type) {
#define HWCAP_LPAE (1 << 20)
static uint32_t ReadELFHWCaps() {
uint32_t result = 0;
#if V8_GLIBC_PREREQ(2, 16)
result = static_cast<uint32_t>(getauxval(AT_HWCAP));
return static_cast<uint32_t>(getauxval(AT_HWCAP));
#else
// Read the ELF HWCAP flags by parsing /proc/self/auxv.
FILE* fp = fopen("/proc/self/auxv", "r");
if (fp != nullptr) {
struct { uint32_t tag; uint32_t value; } entry;
for (;;) {
size_t n = fread(&entry, sizeof(entry), 1, fp);
if (n == 0 || (entry.tag == 0 && entry.value == 0)) {
break;
}
if (entry.tag == AT_HWCAP) {
result = entry.value;
break;
}
}
fclose(fp);
char** head = environ;
while (*head++ != nullptr) {
}
#ifdef __LP64__
using elf_auxv_t = Elf64_auxv_t;
#else
using elf_auxv_t = Elf32_auxv_t;
#endif
for (elf_auxv_t* entry = reinterpret_cast<elf_auxv_t*>(head);
entry->a_type != AT_NULL; ++entry) {
if (entry->a_type == AT_HWCAP) {
return entry->a_un.a_val;
}
}
return 0u;
#endif
return result;
}
#endif // V8_HOST_ARCH_ARM
@ -608,33 +606,28 @@ CPU::CPU()
#ifndef USE_SIMULATOR
#if V8_OS_LINUX
// Read processor info from /proc/self/auxv.
char* auxv_cpu_type = nullptr;
FILE* fp = fopen("/proc/self/auxv", "r");
if (fp != nullptr) {
char** head = environ;
while (*head++ != nullptr) {
}
#if V8_TARGET_ARCH_PPC64
Elf64_auxv_t entry;
using elf_auxv_t = Elf64_auxv_t;
#else
Elf32_auxv_t entry;
using elf_auxv_t = Elf32_auxv_t;
#endif
for (;;) {
size_t n = fread(&entry, sizeof(entry), 1, fp);
if (n == 0 || entry.a_type == AT_NULL) {
for (elf_auxv_t* entry = reinterpret_cast<elf_quxv_t*>(head);
entry->a_type != AT_NULL; ++entry) {
switch (entry->a_type) {
case AT_PLATFORM:
auxv_cpu_type = reinterpret_cast<char*>(entry->a_un.a_val);
break;
case AT_ICACHEBSIZE:
icache_line_size_ = entry->a_un.a_val;
break;
case AT_DCACHEBSIZE:
dcache_line_size_ = entry->a_un.a_val;
break;
}
switch (entry.a_type) {
case AT_PLATFORM:
auxv_cpu_type = reinterpret_cast<char*>(entry.a_un.a_val);
break;
case AT_ICACHEBSIZE:
icache_line_size_ = entry.a_un.a_val;
break;
case AT_DCACHEBSIZE:
dcache_line_size_ = entry.a_un.a_val;
break;
}
}
fclose(fp);
}
part_ = -1;