Thanks,
Jan
gdb/
2012-04-11 Jan Kratochvil<jan.kratochvil@redhat.com>
* linux-nat.c (linux_proc_xfer_partial): Do not check for LEN size and
support also WRITEBUF.
(linux_xfer_partial): Move here the LEN check from
linux_proc_xfer_partial but also call linux_proc_xfer_partial as a last
resort if super_xfer_partial fails.
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -4494,9 +4494,9 @@ linux_nat_make_corefile_notes (bfd *obfd, int *note_size)
}
/* Implement the to_xfer_partial interface for memory reads using the /proc
- filesystem. Because we can use a single read() call for /proc, this
- can be much more efficient than banging away at PTRACE_PEEKTEXT,
- but it doesn't support writes. */
+ filesystem. Because we can use a single read or write call for /proc, this
+ can be much more efficient than banging away at PTRACE_PEEKTEXT or
+ PTRACE_POKETEXT. */
static LONGEST
linux_proc_xfer_partial (struct target_ops *ops, enum target_object object,
@@ -4508,29 +4508,35 @@ linux_proc_xfer_partial (struct target_ops *ops, enum target_object object,
int fd;
char filename[64];
- if (object != TARGET_OBJECT_MEMORY || !readbuf)
- return 0;
-
- /* Don't bother for one word. */
- if (len< 3 * sizeof (long))
+ if (object != TARGET_OBJECT_MEMORY)
return 0;
/* We could keep this file open and cache it - possibly one per
thread. That requires some juggling, but is even faster. */
sprintf (filename, "/proc/%d/mem", PIDGET (inferior_ptid));
- fd = open (filename, O_RDONLY | O_LARGEFILE);
+ fd = open (filename, (readbuf ? O_RDONLY : O_WRONLY) | O_LARGEFILE);
if (fd == -1)
return 0;
- /* If pread64 is available, use it. It's faster if the kernel
+ /* If pread64 or pwrite64 is available, use it. It's faster if the kernel
supports it (only one syscall), and it's 64-bit safe even on
32-bit platforms (for instance, SPARC debugging a SPARC64
application). */
+ if ((readbuf != NULL
+#ifdef HAVE_PREAD64
+&& (pread64 (fd, readbuf, len, offset) != len)
+#else
+&& (lseek (fd, offset, SEEK_SET) == -1 || read (fd, readbuf, len) != len)
+#endif
+ )
+ || (writebuf != NULL
#ifdef HAVE_PREAD64
- if (pread64 (fd, readbuf, len, offset) != len)
+ && (pwrite64 (fd, writebuf, len, offset) != len)
#else
- if (lseek (fd, offset, SEEK_SET) == -1 || read (fd, readbuf, len) != len)
+ && (lseek (fd, offset, SEEK_SET) == -1
+ || write (fd, writebuf, len) != len)
#endif
+ ))
ret = 0;
else
ret = len;
@@ -4759,13 +4765,24 @@ linux_xfer_partial (struct target_ops *ops, enum target_object object,
offset&= ((ULONGEST) 1<< addr_bit) - 1;
}
- xfer = linux_proc_xfer_partial (ops, object, annex, readbuf, writebuf,
- offset, len);
+ /* Use more expensive linux_proc_xfer_partial only for larger transfers. */
+ if (len>= 3 * sizeof (long))
+ {
+ xfer = linux_proc_xfer_partial (ops, object, annex, readbuf, writebuf,
+ offset, len);
+ if (xfer != 0)
+ return xfer;
+ }
+
+ xfer = super_xfer_partial (ops, object, annex, readbuf, writebuf,
+ offset, len);
if (xfer != 0)
return xfer;
- return super_xfer_partial (ops, object, annex, readbuf, writebuf,
- offset, len);
+ /* PTRACE_* of super_xfer_partial may not work if the inferior is running.
+ linux_proc_xfer_partial still may work in such case. */
+ return linux_proc_xfer_partial (ops, object, annex, readbuf, writebuf,
+ offset, len);
}
static void