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selftests/bpf: Test terminal gotox instructions

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Add tests that place gotox at the end of the main program and a
subprogram, with each jump-table target preceding the gotox instruction.
This tests gotox as a valid non-fallthrough terminal instruction.

Signed-off-by: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com>
Link: https://lore.kernel.org/r/20260902171414.96165-2-sidchintamaneni@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Siddharth Chintamaneni 2026-09-02 17:14:14 +00:00 committed by Alexei Starovoitov
parent 0d7823cd4c
commit ac781acaef
1 changed files with 48 additions and 0 deletions
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48
tools/testing/selftests/bpf/progs/verifier_gotox.c
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@ -47,6 +47,54 @@ DEFINE_SIMPLE_JUMP_TABLE_PROG(reserved_field_src_reg, BPF_REG_1, 0, 0, __fa
DEFINE_SIMPLE_JUMP_TABLE_PROG(reserved_field_non_zero_off, BPF_REG_0, 1, 0, __failure __msg("BPF_JA|BPF_X uses reserved fields"))
DEFINE_SIMPLE_JUMP_TABLE_PROG(reserved_field_non_zero_imm, BPF_REG_0, 0, 1, __failure __msg("BPF_JA|BPF_X uses reserved fields"))
#define DEFINE_TERMINAL_GOTOX_PROG(NAME, BASE) \
__naked void NAME(void) \
{ \
asm volatile (" \
.pushsection .jumptables,\"\",@progbits; \
jt0_%=: \
.quad ret0_%= - " BASE "; \
.size jt0_%=, 8; \
.global jt0_%=; \
.popsection; \
\
r0 = jt0_%= ll; \
r0 = *(u64 *)(r0 + 0); \
goto end_%=; \
ret0_%=: \
r0 = 0; \
exit; \
end_%=: \
.8byte %[gotox_r0]; \
" : \
: __imm_insn(gotox_r0, BPF_RAW_INSN(BPF_JMP | BPF_JA | BPF_X, \
BPF_REG_0, 0, 0, 0)) \
: __clobber_all); \
}
SEC("socket")
__success __retval(0)
DEFINE_TERMINAL_GOTOX_PROG(jump_table_terminal_gotox, "socket")
static __noinline __used
DEFINE_TERMINAL_GOTOX_PROG(terminal_gotox_subprog1, ".text")
static __noinline __used int terminal_gotox_subprog2(void)
{
return 0;
}
SEC("socket")
__success __retval(0)
__naked void jump_table_terminal_gotox_subprog(void)
{
asm volatile (" \
call terminal_gotox_subprog1; \
call terminal_gotox_subprog2; \
exit; \
" ::: __clobber_all);
}
/*
* Gotox is forbidden when there is no jump table loaded
* which points to the sub-function where the gotox is used