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[PATCH] [arm] Fix fails in gdb.base/disp-step-syscall.exp
- From: Yao Qi <qiyaoltc at gmail dot com>
- To: gdb-patches at sourceware dot org
- Date: Wed, 15 Apr 2015 14:51:39 +0100
- Subject: [PATCH] [arm] Fix fails in gdb.base/disp-step-syscall.exp
- Authentication-results: sourceware.org; auth=none
From: Yao Qi <yao.qi@linaro.org>
Hi,
I see this fail on arm-linux target,
FAIL: gdb.base/disp-step-syscall.exp: fork: single step over fork final pc
which is caused by the PC isn't expected after displaced stepping the
svc instruction. The code is:
=> 0xb6ead9a4 <__libc_do_syscall+4>: svc 0
0xb6ead9a6 <__libc_do_syscall+6>: pop {r7, pc}
0xb6ead9a8: nop.w^M
0xb6ead9ac: nop.w
after single step svc instruction, pc should be 0xb6ead9a6, but the
actual value of pc is 0xb6ead9a8. The problem is illustrated by
turning on debug message of displaced stepping,
stepi^M
displaced: stepping Thread 12031 now^M
displaced: saved 0x8574: 02 bc 6a 46 04 b4 01 b4 df f8 10 c0 4d f8 04 cd 03 48 04 4b ff f7 d2 ef ff f7 e8 ef 0d 87 00 00 ^M
displaced: process thumb insn df00 at b6ead9a4^M
displaced: copying svc insn df00^M
displaced: read r7 value 00000078^M
displaced: sigreturn/rt_sigreturn SVC call not in signal trampoline frame^M
displaced: writing insn df00 at 00008574^M
displaced: copy 0xb6ead9a4->0x8574: displaced: check mode of b6ead9a4 instead of 00008574^M
displaced: displaced pc to 0x8574^M
displaced: run 0x8574: 00 df 01 de ^M
displaced: restored Thread 12031 0x8574^M
displaced: PC is apparently 00008576 after SVC step (within scratch space)^M
displaced: writing pc b6ead9a8 <----- WRONG ADDRESS
GDB writes the wrong address back to pc because GDB thinks the
instruction size is 4, which isn't true for thumb instruction.
This patch is to replace 4 with dsc->insn_size.
I'll commit it.
gdb:
2015-04-15 Yao Qi <yao.qi@linaro.org>
* arm-linux-tdep.c (arm_linux_cleanup_svc): Use
dsc->insn_size instead of 4.
---
gdb/arm-linux-tdep.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c
index f58da84..adc7831 100644
--- a/gdb/arm-linux-tdep.c
+++ b/gdb/arm-linux-tdep.c
@@ -939,7 +939,6 @@ arm_linux_cleanup_svc (struct gdbarch *gdbarch,
struct regcache *regs,
struct displaced_step_closure *dsc)
{
- CORE_ADDR from = dsc->insn_addr;
ULONGEST apparent_pc;
int within_scratch;
@@ -960,7 +959,8 @@ arm_linux_cleanup_svc (struct gdbarch *gdbarch,
}
if (within_scratch)
- displaced_write_reg (regs, dsc, ARM_PC_REGNUM, from + 4, BRANCH_WRITE_PC);
+ displaced_write_reg (regs, dsc, ARM_PC_REGNUM,
+ dsc->insn_addr + dsc->insn_size, BRANCH_WRITE_PC);
}
static int
--
1.9.1