[PATCH] arc: Write correct "eret" value during register collection
Shahab Vahedi
shahab.vahedi@gmail.com
Thu Nov 12 13:43:10 GMT 2020
From: Shahab Vahedi <shahab@synopsys.com>
In collect_register() function of arc-linux-tdep.c, the "eret"
(exception return) register value was not being reported correctly.
This patch fixes that.
Background:
When asked for the "pc" value, we have to update the "eret" register
with GDB's STOP_PC. The "eret" instructs the kernel code where to
jump back when an instruction has stopped due to a breakpoint. This
is how collect_register() was doing so:
--------------8<--------------
if (regnum == gdbarch_pc_regnum (gdbarch))
regnum = ARC_ERET_REGNUM;
regcache->raw_collect (regnum, buf + arc_linux_core_reg_offsets[regnum]);
-------------->8--------------
Root cause:
Although this is using the correct offset (ERET register's), it is also
changing the REGNUM itself. Therefore, raw_collect (regnum, ...) is
not reading from "pc" anymore.
gdb/ChangeLog:
* arc-linux-tdep.c (collect_register): Use "eret" value while
still writing to "pc" register cache.
---
gdb/arc-linux-tdep.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/gdb/arc-linux-tdep.c b/gdb/arc-linux-tdep.c
index 9ff5f1214a1..3530c7cbdd8 100644
--- a/gdb/arc-linux-tdep.c
+++ b/gdb/arc-linux-tdep.c
@@ -319,9 +319,13 @@ static void
collect_register (const struct regcache *regcache, struct gdbarch *gdbarch,
int regnum, gdb_byte *buf)
{
+ int offset;
+
/* Skip non-existing registers. */
- if ((arc_linux_core_reg_offsets[regnum] == ARC_OFFSET_NO_REGISTER))
+ if (arc_linux_core_reg_offsets[regnum] == ARC_OFFSET_NO_REGISTER)
return;
+ else
+ offset = arc_linux_core_reg_offsets[ARC_ERET_REGNUM];
/* The address where the execution has stopped is in pseudo-register
STOP_PC. However, when kernel code is returning from the exception,
@@ -332,8 +336,8 @@ collect_register (const struct regcache *regcache, struct gdbarch *gdbarch,
the program will continue at the address after the current instruction.
*/
if (regnum == gdbarch_pc_regnum (gdbarch))
- regnum = ARC_ERET_REGNUM;
- regcache->raw_collect (regnum, buf + arc_linux_core_reg_offsets[regnum]);
+ offset = arc_linux_core_reg_offsets[ARC_ERET_REGNUM];
+ regcache->raw_collect (regnum, buf + offset);
}
void
--
2.29.2
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