From: Bruno Larsen Date: Wed, 26 Apr 2023 13:09:38 +0000 (+0200) Subject: gdb/testsuite: change hardcoded assembly in gdb.arch/disp-step-insn-reloc.exp X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=9196be90bd9572bd09fad63d7e0b2fa199738b90;p=binutils-gdb.git 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 : 11ae: e8 f1 ff ff ff callq 11a4 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 11c0: e8 5b 00 00 00 callq 1220 11c5: e9 05 00 00 00 jmpq 11cf 11ca: e8 61 00 00 00 callq 1230 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 : 40112c: e8 f4 ff ff ff callq 401125 401131: 89 45 fc mov %eax,-0x4(%rbp) 401134: 83 7d fc 01 cmpl $0x1,-0x4(%rbp) 401138: 75 07 jne 401141 40113a: e8 c7 ff ff ff callq 401106 40113f: eb 05 jmp 401146 401141: e8 c7 ff ff ff callq 40110d 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 --- diff --git a/gdb/testsuite/gdb.arch/insn-reloc.c b/gdb/testsuite/gdb.arch/insn-reloc.c index f687c2c5631..365e6180057 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)