From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>,
<martin.lau@kernel.org>
Cc: <andrii@kernel.org>, <kernel-team@meta.com>
Subject: [PATCH v2 bpf-next 07/10] selftests/bpf: validate zero preservation for sub-slot loads
Date: Mon, 20 Nov 2023 16:22:18 -0800 [thread overview]
Message-ID: <20231121002221.3687787-8-andrii@kernel.org> (raw)
In-Reply-To: <20231121002221.3687787-1-andrii@kernel.org>
Validate that 1-, 2-, and 4-byte loads from stack slots not aligned on
8-byte boundary still preserve zero, when loading from all-STACK_ZERO
sub-slots, or when stack sub-slots are covered by spilled register with
known constant zero value.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
.../selftests/bpf/progs/verifier_spill_fill.c | 62 +++++++++++++++++++
1 file changed, 62 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
index 899a74ac9093..60ad2e0247b4 100644
--- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
+++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
@@ -486,4 +486,66 @@ __naked void spill_subregs_preserve_stack_zero(void)
: __clobber_all);
}
+char single_byte_buf[1] SEC(".data.single_byte_buf");
+
+SEC("raw_tp")
+__log_level(2)
+__success
+__naked void partial_stack_load_preserves_zeros(void)
+{
+ asm volatile (
+ /* fp-8 is all STACK_ZERO */
+ "*(u64 *)(r10 -8) = 0;"
+
+ /* fp-16 is const zero register */
+ "r0 = 0;"
+ "*(u64 *)(r10 -16) = r0;"
+
+ /* load single U8 from non-aligned STACK_ZERO slot */
+ "r1 = %[single_byte_buf];"
+ "r2 = *(u8 *)(r10 -1);"
+ "r1 += r2;" /* this should be fine */
+
+ /* load single U8 from non-aligned ZERO REG slot */
+ "r1 = %[single_byte_buf];"
+ "r2 = *(u8 *)(r10 -9);"
+ "r1 += r2;" /* this should be fine */
+
+ /* load single U16 from non-aligned STACK_ZERO slot */
+ "r1 = %[single_byte_buf];"
+ "r2 = *(u16 *)(r10 -2);"
+ "r1 += r2;" /* this should be fine */
+
+ /* load single U16 from non-aligned ZERO REG slot */
+ "r1 = %[single_byte_buf];"
+ "r2 = *(u16 *)(r10 -10);"
+ "r1 += r2;" /* this should be fine */
+
+ /* load single U32 from non-aligned STACK_ZERO slot */
+ "r1 = %[single_byte_buf];"
+ "r2 = *(u32 *)(r10 -4);"
+ "r1 += r2;" /* this should be fine */
+
+ /* load single U32 from non-aligned ZERO REG slot */
+ "r1 = %[single_byte_buf];"
+ "r2 = *(u32 *)(r10 -12);"
+ "r1 += r2;" /* this should be fine */
+
+ /* for completeness, load U64 from STACK_ZERO slot */
+ "r1 = %[single_byte_buf];"
+ "r2 = *(u64 *)(r10 -8);"
+ "r1 += r2;" /* this should be fine */
+
+ /* for completeness, load U64 from ZERO REG slot */
+ "r1 = %[single_byte_buf];"
+ "r2 = *(u64 *)(r10 -16);"
+ "r1 += r2;" /* this should be fine */
+
+ "r0 = 0;"
+ "exit;"
+ :
+ : __imm_ptr(single_byte_buf)
+ : __clobber_common);
+}
+
char _license[] SEC("license") = "GPL";
--
2.34.1
next prev parent reply other threads:[~2023-11-21 0:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-21 0:22 [PATCH v2 bpf-next 00/10] Complete BPF verifier precision tracking support for register spills Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 01/10] bpf: support non-r10 register spill/fill to/from stack in precision tracking Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 02/10] selftests/bpf: add stack access precision test Andrii Nakryiko
2023-11-21 0:42 ` Eduard Zingerman
2023-11-21 0:22 ` [PATCH v2 bpf-next 03/10] bpf: fix check for attempt to corrupt spilled pointer Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 04/10] bpf: preserve STACK_ZERO slots on partial reg spills Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 05/10] selftests/bpf: validate STACK_ZERO is preserved on subreg spill Andrii Nakryiko
2023-11-21 0:55 ` Eduard Zingerman
2023-11-21 0:22 ` [PATCH v2 bpf-next 06/10] bpf: preserve constant zero when doing partial register restore Andrii Nakryiko
2023-11-21 16:20 ` Eduard Zingerman
2023-11-21 18:14 ` Andrii Nakryiko
2023-11-21 20:22 ` Eduard Zingerman
2023-11-21 0:22 ` Andrii Nakryiko [this message]
2023-11-21 16:20 ` [PATCH v2 bpf-next 07/10] selftests/bpf: validate zero preservation for sub-slot loads Eduard Zingerman
2023-11-21 18:15 ` Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 08/10] bpf: track aligned STACK_ZERO cases as imprecise spilled registers Andrii Nakryiko
2023-11-21 20:38 ` Alexei Starovoitov
2023-11-21 22:01 ` Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 09/10] selftests/bpf: validate precision logic in partial_stack_load_preserves_zeros Andrii Nakryiko
2023-11-21 16:20 ` Eduard Zingerman
2023-11-21 0:22 ` [PATCH v2 bpf-next 10/10] bpf: use common instruction history across all states Andrii Nakryiko
2023-11-21 16:20 ` Eduard Zingerman
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