This is the mail archive of the gdb-patches@sourceware.org mailing list for the GDB project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[PATCH] avr-tdep.c (avr_scan_prologue): minor fix in prologue scanning


I use GDB from Eclipse with Avarice to debug AVR microcontrollers.
While single stepping (stepi) through the instructions of a normal
function prologue, stepping over the sbiw r28, 0x0f instruction, which
is near the end of the prologue, causes the following change in the
output of backtrace:

Before:
#0 0x000042b0 in HID_Device_USBTask (HIDInterfaceInfo=0x80b8b8) at
../../LUFA/Drivers/USB/Class/Device/HIDClassDevice.c:157
#1 0x000002e0 in main () at HIDRadio.c:83

After:
#0 0x000042b2 in HID_Device_USBTask (HIDInterfaceInfo=0x8000ff) at
../../LUFA/Drivers/USB/Class/Device/HIDClassDevice.c:157
#1 0x00017170 in ?? ()

Note that the frame #1 is inconsistent.

If you now return from frame #0 with the command finish, the target does
not stop at the return address at main. Instead, the target starts
running and it's necessary to stop it.

This is not a big issue and I'm not an expert of the gdb internals but
the fix seems easy enough.


2015-08-20 Cristiano De Alti <cristiano_dealti@hotmail.com>

* avr-tdep.c (avr_scan_prologue): minor fix in prologue scanning.


diff --git a/gdb/avr-tdep.c b/gdb/avr-tdep.c
index 3b99bd2..32a6540 100644
--- a/gdb/avr-tdep.c
+++ b/gdb/avr-tdep.c
@@ -832,25 +832,26 @@ avr_scan_prologue (struct gdbarch *gdbarch,
CORE_ADDR pc_beg, CORE_ADDR pc_end,
or signal handler functions, which is why we set the prologue type
when we saw the beginning of the prologue previously. */

- if (vpc + sizeof (img_sig) < len
+ if (vpc + sizeof (img_sig) <= len
&& memcmp (prologue + vpc, img_sig, sizeof (img_sig)) == 0)
{
+ info->size += locals_size;
vpc += sizeof (img_sig);
}
- else if (vpc + sizeof (img_int) < len
+ else if (vpc + sizeof (img_int) <= len
&& memcmp (prologue + vpc, img_int, sizeof (img_int)) == 0)
{
+ info->size += locals_size;
vpc += sizeof (img_int);
}
- if (vpc + sizeof (img) < len
+ if (vpc + sizeof (img) <= len
&& memcmp (prologue + vpc, img, sizeof (img)) == 0)
{
+ info->size += locals_size;
info->prologue_type = AVR_PROLOGUE_NORMAL;
vpc += sizeof (img);
}

- info->size += locals_size;
-
/* Fall through. */
}


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]