Commit 49859de9 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add a selftest for checking subreg equality 



Add a selftest to ensure subreg equality if source register
upper 32bit is 0. Without previous patch, the test will
fail verification.

Acked-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230417222139.360607-1-yhs@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 3be49f79

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

+2 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include "verifier_meta_access.skel.h"

#include "verifier_raw_stack.skel.h"

#include "verifier_raw_tp_writable.skel.h"

#include "verifier_reg_equal.skel.h"

#include "verifier_ringbuf.skel.h"

#include "verifier_spill_fill.skel.h"

#include "verifier_stack_ptr.skel.h"
@@ -95,6 +96,7 @@ void test_verifier_masking(void) { RUN(verifier_masking); } 
void test_verifier_meta_access(void)          { RUN(verifier_meta_access); }

void test_verifier_raw_stack(void)            { RUN(verifier_raw_stack); }

void test_verifier_raw_tp_writable(void)      { RUN(verifier_raw_tp_writable); }

void test_verifier_reg_equal(void)            { RUN(verifier_reg_equal); }

void test_verifier_ringbuf(void)              { RUN(verifier_ringbuf); }

void test_verifier_spill_fill(void)           { RUN(verifier_spill_fill); }

void test_verifier_stack_ptr(void)            { RUN(verifier_stack_ptr); }

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

0 → 100644
+58 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "bpf_misc.h"



SEC("socket")

__description("check w reg equal if r reg upper32 bits 0")

__success

__naked void subreg_equality_1(void)

{

	asm volatile ("					\

	call %[bpf_ktime_get_ns];			\

	*(u64 *)(r10 - 8) = r0;				\

	r2 = *(u32 *)(r10 - 8);				\

	/* At this point upper 4-bytes of r2 are 0,	\

	 * thus insn w3 = w2 should propagate reg id,	\

	 * and w2 < 9 comparison would also propagate	\

	 * the range for r3.				\

	 */						\

	w3 = w2;					\

	if w2 < 9 goto l0_%=;				\

	exit;						\

l0_%=:	if r3 < 9 goto l1_%=;				\

	/* r1 read is illegal at this point */		\

	r0 -= r1;					\

l1_%=:	exit;						\

"	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



SEC("socket")

__description("check w reg not equal if r reg upper32 bits not 0")

__failure __msg("R1 !read_ok")

__naked void subreg_equality_2(void)

{

	asm volatile ("					\

	call %[bpf_ktime_get_ns];			\

	r2 = r0;					\

	/* Upper 4-bytes of r2 may not be 0, thus insn	\

	 * w3 = w2 should not propagate reg id,	and	\

	 * w2 < 9 comparison should not propagate	\

	 * the range for r3 either.			\

	 */						\

	w3 = w2;					\

	if w2 < 9 goto l0_%=;				\

	exit;						\

l0_%=:	if r3 < 9 goto l1_%=;				\

	/* r1 read is illegal at this point */		\

	r0 -= r1;					\

l1_%=:	exit;						\

"	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



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