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author | Christopher Ferris <cferris@google.com> | 2016-10-12 12:39:18 -0700 |
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committer | Christopher Ferris <cferris@google.com> | 2016-10-12 12:43:55 -0700 |
commit | 279843e1397aff2aedb5e5ffe513893fa1f6767f (patch) | |
tree | ec84adb526e013e66ae26b60bbdc1554b3f28eff /libbacktrace | |
parent | bd6c6eb0e46794873a77a5bdf07e2abd3f6b1664 (diff) | |
download | core-279843e1397aff2aedb5e5ffe513893fa1f6767f.tar.gz core-279843e1397aff2aedb5e5ffe513893fa1f6767f.tar.bz2 core-279843e1397aff2aedb5e5ffe513893fa1f6767f.zip |
Use process_vm_readv to read memory.
Modify BacktracePtrace::Read to use the process_vm_readv syscall
instead of doing multiple ptrace calls.
Test: Ran the backtrace unit tests on host and on x86_64 emulator.
Change-Id: I24c2787f6713d8eb44312f3aa751d1f6d9d34719
Diffstat (limited to 'libbacktrace')
-rw-r--r-- | libbacktrace/BacktracePtrace.cpp | 45 |
1 files changed, 12 insertions, 33 deletions
diff --git a/libbacktrace/BacktracePtrace.cpp b/libbacktrace/BacktracePtrace.cpp index fd8b7134f..148c41810 100644 --- a/libbacktrace/BacktracePtrace.cpp +++ b/libbacktrace/BacktracePtrace.cpp @@ -17,6 +17,7 @@ #include <errno.h> #include <stdint.h> #include <string.h> +#include <sys/uio.h> #include <sys/param.h> #include <sys/ptrace.h> #include <sys/types.h> @@ -72,42 +73,20 @@ size_t BacktracePtrace::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) { if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) { return 0; } - bytes = MIN(map.end - addr, bytes); - size_t bytes_read = 0; - word_t data_word; - size_t align_bytes = addr & (sizeof(word_t) - 1); - if (align_bytes != 0) { - if (!PtraceRead(Tid(), addr & ~(sizeof(word_t) - 1), &data_word)) { - return 0; - } - size_t copy_bytes = MIN(sizeof(word_t) - align_bytes, bytes); - memcpy(buffer, reinterpret_cast<uint8_t*>(&data_word) + align_bytes, copy_bytes); - addr += copy_bytes; - buffer += copy_bytes; - bytes -= copy_bytes; - bytes_read += copy_bytes; - } - size_t num_words = bytes / sizeof(word_t); - for (size_t i = 0; i < num_words; i++) { - if (!PtraceRead(Tid(), addr, &data_word)) { - return bytes_read; - } - memcpy(buffer, &data_word, sizeof(word_t)); - buffer += sizeof(word_t); - addr += sizeof(word_t); - bytes_read += sizeof(word_t); - } + struct iovec local_io; + local_io.iov_base = buffer; + local_io.iov_len = bytes; - size_t left_over = bytes & (sizeof(word_t) - 1); - if (left_over) { - if (!PtraceRead(Tid(), addr, &data_word)) { - return bytes_read; - } - memcpy(buffer, &data_word, left_over); - bytes_read += left_over; + struct iovec remote_io; + remote_io.iov_base = reinterpret_cast<void*>(addr); + remote_io.iov_len = bytes; + + ssize_t bytes_read = process_vm_readv(Tid(), &local_io, 1, &remote_io, 1, 0); + if (bytes_read == -1) { + return 0; } - return bytes_read; + return static_cast<size_t>(bytes_read); #endif } |