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| author | Bruno Larsen <blarsen@redhat.com> | 2023-04-26 15:09:38 +0200 |
|---|---|---|
| committer | Bruno Larsen <blarsen@redhat.com> | 2023-05-23 10:48:20 +0200 |
| commit | 9196be90bd9572bd09fad63d7e0b2fa199738b90 (patch) | |
| tree | 6009da45f3ad53744236ece59699ba7cf974745a /gdb | |
| parent | a4f8c177b46fe96b08a066c159a7a11071095a30 (diff) | |
| download | gdb-9196be90bd9572bd09fad63d7e0b2fa199738b90.zip gdb-9196be90bd9572bd09fad63d7e0b2fa199738b90.tar.gz gdb-9196be90bd9572bd09fad63d7e0b2fa199738b90.tar.bz2 | |
gdb/testsuite: change hardcoded assembly in gdb.arch/disp-step-insn-reloc.exp
When testing gdb.arch/disp-step-insn-reloc.exp with clang in an x86_64
machine, the compiled test case would segfault when returning from
the function can_relocate_call, with a suggestion of a broken stack.
The example assembly in the commment was the following:
f:
MOV $1, %[ok]
JMP end
set_point0:
CALL f ; tracepoint here.
end:
And the segmentation fault happening at the final "ret" instruction of
can_relocate_call. Looking at the disassembled version of the later
half of the important function, we see:
Clang version (f starting at 11a4):
00000000000011ae <set_point0>:
11ae: e8 f1 ff ff ff callq 11a4 <can_relocate_call+0x14>
11b3: 89 45 fc mov %eax,-0x4(%rbp)
11b6: 83 7d fc 01 cmpl $0x1,-0x4(%rbp)
11ba: 0f 85 0a 00 00 00 jne 11ca <set_point0+0x1c>
11c0: e8 5b 00 00 00 callq 1220 <pass>
11c5: e9 05 00 00 00 jmpq 11cf <set_point0+0x21>
11ca: e8 61 00 00 00 callq 1230 <fail>
11cf: 48 83 c4 10 add $0x10,%rsp
11d3: 5d pop %rbp
11d4: c3 retq
11d5: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1)
11dc: 00 00 00 00
gcc version (f starting at 401125):
000000000040112c <set_point0>:
40112c: e8 f4 ff ff ff callq 401125 <can_relocate_call+0x11>
401131: 89 45 fc mov %eax,-0x4(%rbp)
401134: 83 7d fc 01 cmpl $0x1,-0x4(%rbp)
401138: 75 07 jne 401141 <set_point0+0x15>
40113a: e8 c7 ff ff ff callq 401106 <pass>
40113f: eb 05 jmp 401146 <set_point0+0x1a>
401141: e8 c7 ff ff ff callq 40110d <fail>
401146: 90 nop
401147: c9 leaveq
401148: c3 retq
The epilogue of set_point0 (11cf for clang, 401146 for gcc) is the main
difference: GCC's version uses the leaveq instruction, which resets rsp
based on rbp, while clang adds the same constant to rsp that it
subtracted in the prologue. Clang fails because the return address that
is added by the "call f" instruction isn't accounted for.
This commit fixes that by adding a return instruction to f, which leaves
the rsp as the compilers would expect.
Approved-By: Andrew Burgess <aburgess@redhat.com>
Diffstat (limited to 'gdb')
| -rw-r--r-- | gdb/testsuite/gdb.arch/insn-reloc.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/gdb/testsuite/gdb.arch/insn-reloc.c b/gdb/testsuite/gdb.arch/insn-reloc.c index f687c2c..365e618 100644 --- a/gdb/testsuite/gdb.arch/insn-reloc.c +++ b/gdb/testsuite/gdb.arch/insn-reloc.c @@ -49,10 +49,9 @@ fail (void) JMP set_point0 f: MOV $1, %[ok] - JMP end + RET set_point0: CALL f ; tracepoint here. - end: */ @@ -65,10 +64,9 @@ can_relocate_call (void) " jmp " SYMBOL (set_point0) "\n" "0:\n" " mov $1, %[ok]\n" - " jmp 1f\n" + " ret\n" SYMBOL (set_point0) ":\n" " call 0b\n" - "1:\n" : [ok] "=r" (ok)); if (ok == 1) |