arm64:uprobe fix the uprobe SWBP_INSN in big-endian
PATCH 1/1 arm64:uprobe fix the uprobe SWBP_INSN in big-endian
From: junhua huang <[email protected]>
We use uprobe in aarch64_be, which we found the tracee task would exit due to SIGILL when we enable the uprobe trace.
We can see the replace inst from uprobe is not correct in aarch big-endian. As in Armv8-A, instruction fetches are always treated as little-endian, we should treat the UPROBE_SWBP_INSN as little-endian。
The test case is as following。
bash-4.4# ./mqueue_test_aarchbe 1 1 2 1 10 > /dev/null & bash-4.4# cd /sys/kernel/debug/tracing/
bash-4.4# echo 'p:test /mqueue_test_aarchbe:0xc30 %x0 %x1' > uprobe_events bash-4.4# echo 1 > events/uprobes/enable
bash-4.4#
bash-4.4# ps
PID TTY TIME CMD
140 ? 00:00:01 bash
237 ? 00:00:00 ps
[1]+ Illegal instruction ./mqueue_test_aarchbe 1 1 2 1 100 > /dev/null
which we debug use gdb as following:
bash-4.4# gdb attach 155
(gdb) disassemble send
Dump of assembler code for function send:
0x0000000000400c30 <+0>: .inst 0xa00020d4 ; undefined 0x0000000000400c34 <+4>: mov x29, sp 0x0000000000400c38 <+8>: str w0, [sp, #28] 0x0000000000400c3c <+12>: strb w1, [sp, #27] 0x0000000000400c40 <+16>: str xzr, [sp, #40] 0x0000000000400c44 <+20>: str xzr, [sp, #48] 0x0000000000400c48 <+24>: add x0, sp, #0x1b 0x0000000000400c4c <+28>: mov w3, #0x0 // #0 0x0000000000400c50 <+32>: mov x2, #0x1 // #1 0x0000000000400c54 <+36>: mov x1, x0 0x0000000000400c58 <+40>: ldr w0, [sp, #28] 0x0000000000400c5c <+44>: bl 0x405e10 <mq_send> 0x0000000000400c60 <+48>: str w0, [sp, #60] 0x0000000000400c64 <+52>: ldr w0, [sp, #60] 0x0000000000400c68 <+56>: ldp x29, x30, [sp], #64 0x0000000000400c6c <+60>: ret
End of assembler dump.
(gdb) info b
No breakpoints or watchpoints.
(gdb) c
Continuing.
Program received signal SIGILL, Illegal instruction. 0x0000000000400c30 in send ()
(gdb) x/10x 0x400c30
0x400c30 <send>: 0xd42000a0 0xfd030091 0xe01f00b9 0xe16f0039 0x400c40 <send+16>: 0xff1700f9 0xff1b00f9 0xe06f0091 0x03008052 0x400c50 <send+32>: 0x220080d2 0xe10300aa (gdb) disassemble 0x400c30 Dump of assembler code for function send: => 0x0000000000400c30 <+0>: .inst 0xa00020d4 ; undefined 0x0000000000400c34 <+4>: mov x29, sp 0x0000000000400c38 <+8>: str w0, [sp, #28] 0x0000000000400c3c <+12>: strb w1, [sp, #27] 0x0000000000400c40 <+16>: str xzr, [sp, #40]
--- arch/arm64/include/asm/uprobes.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
arch/arm64/include/asm/uprobes.h +1 -1
@@ -12,7 +12,7 @@#define MAX_UINSN_BYTES AARCH64_INSN_SIZE -#define UPROBE_SWBP_INSN BRK64_OPCODE_UPROBES +#define UPROBE_SWBP_INSN cpu_to_le32(BRK64_OPCODE_UPROBES)#define UPROBE_SWBP_INSN_SIZE AARCH64_INSN_SIZE#define UPROBE_XOL_SLOT_BYTES MAX_UINSN_BYTES
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Quoted 9 lines · On Fri, 2 Dec 2022 15:11:10 +0800 (CST), [email protected] wrote:
From: junhua huang <[email protected]>
We use uprobe in
aarch64_be, which we found the tracee task would exit due to SIGILL when we enable the uprobe trace.
We can see the replace inst from uprobe is not correct in aarch big-endian. As in Armv8-A, instruction fetches are always treated as little-endian, we should treat theUPROBE_SWBP_INSNas little-endian。[...]
Applied to arm64 (for-next/insn), thanks!
[1/1] arm64:uprobe fix the uprobe SWBP_INSN in big-endian
https://git.kernel.org/arm64/c/60f07e22a73d
Cheers,
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