| Message ID | 1429105899-9232-1-git-send-email-qiyaoltc@gmail.com |
|---|---|
| State | New |
| Headers | show |
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
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(-)