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41f071ef33
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.
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.
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