From 10dadadc5b239b7dfcd1f1f9a4e45facfffeb4f5 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Mon, 11 Jan 2021 18:24:55 +0100 Subject: [PATCH] [gdb/testsuite] Fix gdb.arch/amd64-stap-three-arg-disp.S On SLE-11 I ran into: ... (gdb) print $_probe_arg0^M Cannot access memory at address 0x8000003fe05c^M (gdb) FAIL: gdb.arch/amd64-stap-special-operands.exp: probe: three_arg: \ print $_probe_arg0 ... The memory cannot be accessed because the address used to evaluate $_probe_arg0 at the probe point is incorrect. The address is calculated using this expression: ... .asciz "-4@-4(%rbp,%ebx,0)" ... which uses $ebx, but $ebx is uninitialized at the probe point. The test-case does contain a "movl $0, %ebx" insn to set $ebx to 0, but that insn is placed after the probe point. We could fix this by moving the insn to before the probe point. But, $ebx is also a callee-save register, so normally, if we modify it, we also need to save and restore it, which is currently not done. This is currently not harmful, because we don't run the test-case further than the probe point, but it's bound to cause confusion. So, fix this instead by using $eax instead in the expression, and moving the insn setting $eax to 0 to before the probe point. gdb/testsuite/ChangeLog: 2021-01-11 Tom de Vries PR testsuite/26968 * gdb.arch/amd64-stap-three-arg-disp.S: Remove insn modifying $ebx. Move insn setting $eax to before probe point. --- gdb/testsuite/ChangeLog | 6 ++++++ gdb/testsuite/gdb.arch/amd64-stap-three-arg-disp.S | 5 ++--- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 03593c5499e..65bbebfb598 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2021-01-11 Tom de Vries + + PR testsuite/26968 + * gdb.arch/amd64-stap-three-arg-disp.S: Remove insn modifying $ebx. + Move insn setting $eax to before probe point. + 2021-01-09 Tom Tromey * gdb.trace/ax.exp: Do not require an "ext". diff --git a/gdb/testsuite/gdb.arch/amd64-stap-three-arg-disp.S b/gdb/testsuite/gdb.arch/amd64-stap-three-arg-disp.S index cf3856f41e9..17b64048082 100644 --- a/gdb/testsuite/gdb.arch/amd64-stap-three-arg-disp.S +++ b/gdb/testsuite/gdb.arch/amd64-stap-three-arg-disp.S @@ -15,6 +15,7 @@ main: movl %edi, -20(%rbp) movq %rsi, -32(%rbp) movl $10, -4(%rbp) + movl $0, %eax #APP # 8 "amd64-stap-three-arg-disp.c" 1 990: nop @@ -28,7 +29,7 @@ main: .8byte 0 .asciz "test" .asciz "three_arg" -.asciz "-4@-4(%rbp,%ebx,0)" +.asciz "-4@-4(%rbp,%eax,0)" 994: .balign 4 .popsection @@ -45,8 +46,6 @@ _.stapsdt.base: .space 1 # 0 "" 2 #NO_APP - movl $0, %eax - movl $0, %ebx popq %rbp .cfi_def_cfa 7, 8 # SUCC: EXIT [100.0%] -- 2.30.2