Commit eff5b5ff authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add a selftest for x86 jit convergence issues 



The core part of the selftest, i.e., the je <-> jmp cycle, mimics the
original sched-ext bpf program. The test will fail without the
previous patch.

I tried to create some cases for other potential cycles
(je <-> je, jmp <-> je and jmp <-> jmp) with similar pattern
to the test in this patch, but failed. So this patch
only contains one test for je <-> jmp cycle.

Signed-off-by: default avatarYonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240904221256.37389-1-yonghong.song@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent c8831bdb

tools/testing/selftests/bpf/prog_tests/verifier.c

+2 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ 
#include "verifier_int_ptr.skel.h"

#include "verifier_iterating_callbacks.skel.h"

#include "verifier_jeq_infer_not_null.skel.h"

#include "verifier_jit_convergence.skel.h"

#include "verifier_ld_ind.skel.h"

#include "verifier_ldsx.skel.h"

#include "verifier_leak_ptr.skel.h"
@@ -163,6 +164,7 @@ void test_verifier_helper_value_access(void) { RUN(verifier_helper_value_access 
void test_verifier_int_ptr(void)              { RUN(verifier_int_ptr); }

void test_verifier_iterating_callbacks(void)  { RUN(verifier_iterating_callbacks); }

void test_verifier_jeq_infer_not_null(void)   { RUN(verifier_jeq_infer_not_null); }

void test_verifier_jit_convergence(void)      { RUN(verifier_jit_convergence); }

void test_verifier_ld_ind(void)               { RUN(verifier_ld_ind); }

void test_verifier_ldsx(void)                  { RUN(verifier_ldsx); }

void test_verifier_leak_ptr(void)             { RUN(verifier_leak_ptr); }

tools/testing/selftests/bpf/progs/verifier_jit_convergence.c

0 → 100644
+114 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "bpf_misc.h"



struct value_t {

	long long a[32];

};



struct {

        __uint(type, BPF_MAP_TYPE_HASH);

        __uint(max_entries, 1);

        __type(key, long long);

        __type(value, struct value_t);

} map_hash SEC(".maps");



SEC("socket")

__description("bpf_jit_convergence je <-> jmp")

__success __retval(0)

__arch_x86_64

__jited("	pushq	%rbp")

__naked void btf_jit_convergence_je_jmp(void)

{

	asm volatile (

	"call %[bpf_get_prandom_u32];"

	"if r0 == 0 goto l20_%=;"

	"if r0 == 1 goto l21_%=;"

	"if r0 == 2 goto l22_%=;"

	"if r0 == 3 goto l23_%=;"

	"if r0 == 4 goto l24_%=;"

	"call %[bpf_get_prandom_u32];"

	"call %[bpf_get_prandom_u32];"

"l20_%=:"

"l21_%=:"

"l22_%=:"

"l23_%=:"

"l24_%=:"

	"r1 = 0;"

	"*(u64 *)(r10 - 8) = r1;"

	"r2 = r10;"

	"r2 += -8;"

	"r1 = %[map_hash] ll;"

	"call %[bpf_map_lookup_elem];"

	"if r0 == 0 goto l1_%=;"

	"r6 = r0;"

	"call %[bpf_get_prandom_u32];"

	"r7 = r0;"

	"r5 = r6;"

	"if r0 != 0x0 goto l12_%=;"

	"call %[bpf_get_prandom_u32];"

	"r1 = r0;"

	"r2 = r6;"

	"if r1 == 0x0 goto l0_%=;"

"l9_%=:"

	"r2 = *(u64 *)(r6 + 0x0);"

	"r2 += 0x1;"

	"*(u64 *)(r6 + 0x0) = r2;"

	"goto l1_%=;"

"l12_%=:"

	"r1 = r7;"

	"r1 += 0x98;"

	"r2 = r5;"

	"r2 += 0x90;"

	"r2 = *(u32 *)(r2 + 0x0);"

	"r3 = r7;"

	"r3 &= 0x1;"

	"r2 *= 0xa8;"

	"if r3 == 0x0 goto l2_%=;"

	"r1 += r2;"

	"r1 -= r7;"

	"r1 += 0x8;"

	"if r1 <= 0xb20 goto l3_%=;"

	"r1 = 0x0;"

	"goto l4_%=;"

"l3_%=:"

	"r1 += r7;"

"l4_%=:"

	"if r1 == 0x0 goto l8_%=;"

	"goto l9_%=;"

"l2_%=:"

	"r1 += r2;"

	"r1 -= r7;"

	"r1 += 0x10;"

	"if r1 <= 0xb20 goto l6_%=;"

	"r1 = 0x0;"

	"goto l7_%=;"

"l6_%=:"

	"r1 += r7;"

"l7_%=:"

	"if r1 == 0x0 goto l8_%=;"

	"goto l9_%=;"

"l0_%=:"

	"r1 = 0x3;"

	"*(u64 *)(r10 - 0x10) = r1;"

	"r2 = r1;"

	"goto l1_%=;"

"l8_%=:"

	"r1 = r5;"

	"r1 += 0x4;"

	"r1 = *(u32 *)(r1 + 0x0);"

	"*(u64 *)(r10 - 0x8) = r1;"

"l1_%=:"

	"r0 = 0;"

	"exit;"

	:

	: __imm(bpf_get_prandom_u32),

	  __imm(bpf_map_lookup_elem),

	  __imm_addr(map_hash)

	: __clobber_all);

}



char _license[] SEC("license") = "GPL";