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Merge branch 'bpf-live-registers-computation-with-gotox'

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Anton Protopopov says:

====================
bpf: Live registers computation with gotox

While adding a selftest for live registers computation with gotox,
I've noticed that the code is actually incomplete. Namely, the
destination register rX in `gotox rX` wasn't actually considered
as used. Fix this and add a selftest.

v1 -> v2:
  * only enable the new selftest on x86 and arm64

v1: https://lore.kernel.org/bpf/20260114113314.32649-1-a.s.protopopov@gmail.com/T/#t
====================

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20260114162544.83253-1-a.s.protopopov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2026-01-14 19:08:10 -08:00
commit 9a403a4aea
2 changed files with 47 additions and 0 deletions
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6
kernel/bpf/verifier.c
View File

@ -24848,6 +24848,12 @@ static void compute_insn_live_regs(struct bpf_verifier_env *env,
case BPF_JMP32:
switch (code) {
case BPF_JA:
def = 0;
if (BPF_SRC(insn->code) == BPF_X)
use = dst;
else
use = 0;
break;
case BPF_JCOND:
def = 0;
use = 0;

41
tools/testing/selftests/bpf/progs/compute_live_registers.c
View File

@ -431,6 +431,47 @@ __naked void subprog1(void)
::: __clobber_all);
}
#if defined(__TARGET_ARCH_x86) || defined(__TARGET_ARCH_arm64)
SEC("socket")
__log_level(2)
__msg("2: .1........ (07) r1 += 8")
__msg("3: .1........ (79) r2 = *(u64 *)(r1 +0)")
__msg("4: ..2....... (b7) r3 = 1")
__msg("5: ..23...... (b7) r4 = 2")
__msg("6: ..234..... (0d) gotox r2")
__msg("7: ...3...... (bf) r0 = r3")
__msg("8: 0......... (95) exit")
__msg("9: ....4..... (bf) r0 = r4")
__msg("10: 0......... (95) exit")
__naked
void gotox(void)
{
asm volatile (
".pushsection .jumptables,\"\",@progbits;"
"jt0_%=: .quad l0_%= - socket;"
".quad l1_%= - socket;"
".size jt0_%=, 16;"
".global jt0_%=;"
".popsection;"
"r1 = jt0_%= ll;"
"r1 += 8;"
"r2 = *(u64 *)(r1 + 0);"
"r3 = 1;"
"r4 = 2;"
".8byte %[gotox_r2];"
"l0_%=: r0 = r3;"
"exit;"
"l1_%=: r0 = r4;"
"exit;"
:
: __imm_insn(gotox_r2, BPF_RAW_INSN(BPF_JMP | BPF_JA | BPF_X, BPF_REG_2, BPF_REG_0, 0, 0))
: __clobber_all);
}
#endif /* __TARGET_ARCH_x86 || __TARGET_ARCH_arm64 */
/* to retain debug info for BTF generation */
void kfunc_root(void)
{