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 #include #include +#include #include #include #include @@ -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(&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(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(bytes_read); #endif }