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| author | Thiago Jung Bauermann <thiago.bauermann@linaro.org> | 2024-04-27 18:38:22 -0300 |
|---|---|---|
| committer | Thiago Jung Bauermann <thiago.bauermann@linaro.org> | 2024-06-07 18:25:06 -0300 |
| commit | b995344c116e04bd6bfeaf53364cd791d0dae45d (patch) | |
| tree | 6db3b94a147300dc45cf962a64aa1721053cfcce /gdb/aarch64-tdep.c | |
| parent | 1a7d840a2164072cb776c21b0bda5710deebd542 (diff) | |
| download | gdb-b995344c116e04bd6bfeaf53364cd791d0dae45d.zip gdb-b995344c116e04bd6bfeaf53364cd791d0dae45d.tar.gz gdb-b995344c116e04bd6bfeaf53364cd791d0dae45d.tar.bz2 | |
gdb/aarch64: Disable displaced single-step for MOPS instructions
The AArch64 MOPS (Memory Operation) instructions provide a standardised
instruction sequence to perform a memset, memcpy or memmove. A sequence is
always composed of three instructions: a prologue instruction, a main
instruction and an epilogue instruction. As an illustration, here are the
implementations of these memory operations in glibc 2.39:
(gdb) disassemble/r
Dump of assembler code for function __memset_mops:
=> 0x0000fffff7e8d780 <+0>: d503201f nop
0x0000fffff7e8d784 <+4>: aa0003e3 mov x3, x0
0x0000fffff7e8d788 <+8>: 19c10443 setp [x3]!, x2!, x1
0x0000fffff7e8d78c <+12>: 19c14443 setm [x3]!, x2!, x1
0x0000fffff7e8d790 <+16>: 19c18443 sete [x3]!, x2!, x1
0x0000fffff7e8d794 <+20>: d65f03c0 ret
End of assembler dump.
(gdb) disassemble/r
Dump of assembler code for function __memcpy_mops:
=> 0x0000fffff7e8c580 <+0>: d503201f nop
0x0000fffff7e8c584 <+4>: aa0003e3 mov x3, x0
0x0000fffff7e8c588 <+8>: 19010443 cpyfp [x3]!, [x1]!, x2!
0x0000fffff7e8c58c <+12>: 19410443 cpyfm [x3]!, [x1]!, x2!
0x0000fffff7e8c590 <+16>: 19810443 cpyfe [x3]!, [x1]!, x2!
0x0000fffff7e8c594 <+20>: d65f03c0 ret
End of assembler dump.
(gdb) disassemble/r
Dump of assembler code for function __memmove_mops:
=> 0x0000fffff7e8d180 <+0>: d503201f nop
0x0000fffff7e8d184 <+4>: aa0003e3 mov x3, x0
0x0000fffff7e8d188 <+8>: 1d010443 cpyp [x3]!, [x1]!, x2!
0x0000fffff7e8d18c <+12>: 1d410443 cpym [x3]!, [x1]!, x2!
0x0000fffff7e8d190 <+16>: 1d810443 cpye [x3]!, [x1]!, x2!
0x0000fffff7e8d194 <+20>: d65f03c0 ret
End of assembler dump.
The Arm Architecture Reference Manual says that "the prologue, main, and
epilogue instructions are expected to be run in succession and to appear
consecutively in memory". Therefore this patch disables displaced stepping
on them.
The testcase verifies that MOPS sequences are correctly single-stepped.
PR tdep/31666
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31666
Approved-By: Luis Machado <luis.machado@arm.com>
Tested-By: Luis Machado <luis.machado@arm.com>
Diffstat (limited to 'gdb/aarch64-tdep.c')
| -rw-r--r-- | gdb/aarch64-tdep.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c index 8d0553f..05ecd42 100644 --- a/gdb/aarch64-tdep.c +++ b/gdb/aarch64-tdep.c @@ -3808,10 +3808,12 @@ aarch64_displaced_step_copy_insn (struct gdbarch *gdbarch, if (aarch64_decode_insn (insn, &inst, 1, NULL) != 0) return NULL; - /* Look for a Load Exclusive instruction which begins the sequence. */ - if (inst.opcode->iclass == ldstexcl && bit (insn, 22)) + /* Look for a Load Exclusive instruction which begins the sequence, + or for a MOPS instruction. */ + if ((inst.opcode->iclass == ldstexcl && bit (insn, 22)) + || AARCH64_CPU_HAS_FEATURE (*inst.opcode->avariant, MOPS)) { - /* We can't displaced step atomic sequences. */ + /* We can't displaced step atomic sequences nor MOPS instructions. */ return NULL; } |