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selftests/bpf: ignore call depth accounting for retbleed in verifier tests

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When running the selftests on a retbleed-affected platform (eg:
Skylake), with call depth accounting enabled
(CONFIG_CALL_DEPTH_TRACKING=y) _and_ with retbleed=stuff, some verifier
selftests fail to validate the jited instructions. For example:

  MATCHED    SUBSTR: '	endbr64'
  MATCHED    SUBSTR: '	nopl	(%rax,%rax)'
  MATCHED    SUBSTR: '	xorq	%rax, %rax'
  MATCHED    SUBSTR: '	pushq	%rbp'
  MATCHED    SUBSTR: '	movq	%rsp, %rbp'
  MATCHED    SUBSTR: '	endbr64'
  MATCHED    SUBSTR: '	cmpq	$0x21, %rax'
  MATCHED    SUBSTR: '	ja	L0'
  MATCHED    SUBSTR: '	pushq	%rax'
  MATCHED    SUBSTR: '	movq	%rsp, %rax'
  MATCHED    SUBSTR: '	jmp	L1'
  MATCHED    SUBSTR: 'L0:	pushq	%rax'
  MATCHED    SUBSTR: 'L1:	pushq	%rax'
  MATCHED    SUBSTR: '	movq	-0x10(%rbp), %rax'
  WRONG LINE  REGEX: '	callq	0x{{.*}}'

Those affected selftests allways fail on some call instruction: this
failure is due to the JIT compiler emitting call depth accounting for
retbleed mitigation (see x86_call_depth_emit_accounting calls in
bpf_jit_comp.c), resulting in an additional instruction being inserted
in front of every call instruction, similar to this one:

  sarq    $0x5, %gs:-0x39882741(%rip)

Fix those selftests by allowing them to ignore this possibly present
call depth accounting instruction.

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260528-fix_tests_for_retbleed_stuff-v1-1-c2022a1f3bee@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexis Lothoré (eBPF Foundation) 2026-05-28 15:27:14 +02:00 committed by Alexei Starovoitov
parent 80b89d0226
commit bf29346fc3
2 changed files with 6 additions and 0 deletions
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5
tools/testing/selftests/bpf/progs/verifier_private_stack.c
View File

@ -94,6 +94,7 @@ __jited(" addq %gs:{{.*}}, %r9")
__jited(" movl $0x2a, %edi")
__jited(" movq %rdi, -0x200(%r9)")
__jited(" pushq %r9")
__jited("...")
__jited(" callq 0x{{.*}}")
__jited(" popq %r9")
__jited(" xorl %eax, %eax")
@ -153,11 +154,13 @@ __jited(" endbr64")
__jited(" movabsq $0x{{.*}}, %r9")
__jited(" addq %gs:{{.*}}, %r9")
__jited(" pushq %r9")
__jited("...")
__jited(" callq")
__jited(" popq %r9")
__jited(" movl $0x2a, %edi")
__jited(" movq %rdi, -0x200(%r9)")
__jited(" pushq %r9")
__jited("...")
__jited(" callq")
__jited(" popq %r9")
__arch_arm64
@ -199,6 +202,7 @@ __description("Private stack, exception in main prog")
__success __retval(0)
__arch_x86_64
__jited(" pushq %r9")
__jited("...")
__jited(" callq")
__jited(" popq %r9")
__arch_arm64
@ -246,6 +250,7 @@ __success __retval(0)
__arch_x86_64
__jited(" movq %rdi, -0x200(%r9)")
__jited(" pushq %r9")
__jited("...")
__jited(" callq")
__jited(" popq %r9")
__arch_arm64

1
tools/testing/selftests/bpf/progs/verifier_tailcall_jit.c
View File

@ -56,6 +56,7 @@ __jited("L1: pushq %rax") /* rbp[-16] = rax */
* (cause original rax might be clobbered by this point)
*/
__jited(" movq -0x10(%rbp), %rax")
__jited("...")
__jited(" callq 0x{{.*}}") /* call to sub() */
__jited(" xorl %eax, %eax")
__jited(" leave")