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

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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: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240904221256.37389-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song
2024-09-04 15:12:56 -07:00
committed by Alexei Starovoitov
parent c8831bdbfb
commit eff5b5fffc
2 changed files with 116 additions and 0 deletions
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2
tools/testing/selftests/bpf/prog_tests/verifier.c
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@@ -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); }

114
tools/testing/selftests/bpf/progs/verifier_jit_convergence.c Normal file
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@@ -0,0 +1,114 @@
// 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";