diff options
Diffstat (limited to 'exec/trace.c')
| -rw-r--r-- | exec/trace.c | 44 |
1 files changed, 43 insertions, 1 deletions
diff --git a/exec/trace.c b/exec/trace.c index cb0839c9cd9..8d107696423 100644 --- a/exec/trace.c +++ b/exec/trace.c @@ -42,6 +42,10 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */ #include <linux/elf.h> /* for NT_* */ #endif /* __aarch64__ */ +#ifdef HAVE_SYS_UIO_H +#include <sys/uio.h> /* for process_vm_readv */ +#endif /* HAVE_SYS_UIO_H */ + /* Program tracing functions. @@ -122,7 +126,10 @@ static struct exec_tracee *tracing_processes; /* Read N bytes from TRACEE's memory, starting at the specified user - ADDRESS. Return its contents in BUFFER. */ + ADDRESS. Return its contents in BUFFER. + + If there are unreadable pages within ADDRESS + N, the contents of + BUFFER after the first such page becomes undefined. */ static void read_memory (struct exec_tracee *tracee, char *buffer, @@ -130,6 +137,25 @@ read_memory (struct exec_tracee *tracee, char *buffer, { USER_WORD word, n_words, n_bytes, i; long rc; +#ifdef HAVE_PROCESS_VM + struct iovec iov, remote; + + /* If `process_vm_readv' is available, use it instead. */ + + iov.iov_base = buffer; + iov.iov_len = n; + remote.iov_base = (void *) address; + remote.iov_len = n; + + /* Return immediately if successful. As long as some bytes were + read, consider the read to have been a success. */ + + if (n <= SSIZE_MAX + && ((size_t) process_vm_readv (tracee->pid, &iov, 1, + &remote, 1, 0) != -1)) + return; + +#endif /* HAVE_PROCESS_VM */ /* First, read entire words from the tracee. */ n_words = n & ~(sizeof (USER_WORD) - 1); @@ -248,6 +274,22 @@ user_copy (struct exec_tracee *tracee, const unsigned char *buffer, { USER_WORD start, end, word; unsigned char *bytes; +#ifdef HAVE_PROCESS_VM + struct iovec iov, remote; + + /* Try to use `process_vm_writev' if possible, but fall back to + ptrace if something bad happens. */ + + iov.iov_base = (void *) buffer; + iov.iov_len = n; + remote.iov_base = (void *) address; + remote.iov_len = n; + + if (n <= SSIZE_MAX + && ((size_t) process_vm_writev (tracee->pid, &iov, 1, + &remote, 1, 0) == n)) + return 0; +#endif /* HAVE_PROCESS_VM */ /* Calculate the start and end positions for the write. */ |