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* [RFC PATCH] arm64: bpf: fix endianness conversion bugs
@ 2015-06-26  1:39 ` Xi Wang
  0 siblings, 0 replies; 6+ messages in thread
From: Xi Wang @ 2015-06-26  1:39 UTC (permalink / raw)
  To: linux-arm-kernel; +Cc: linux-kernel, Xi Wang, Zi Shen Lim, Alexei Starovoitov

Upper bits should be zeroed in endianness conversion:

- even when there's no need to change endianness (i.e., BPF_FROM_BE
  on big endian or BPF_FROM_LE on little endian);

- after rev16.

This patch fixes such bugs by emitting extra instructions to clear
upper bits.

Cc: Zi Shen Lim <zlim.lnx@gmail.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
Signed-off-by: Xi Wang <xi.wang@gmail.com>
---
The current testsuite catches the 16-bit bugs.  I'll send a separate
patch that extends test_bpf to catch the 32-bit ones.
---
 arch/arm64/net/bpf_jit.h      |  4 ++++
 arch/arm64/net/bpf_jit_comp.c | 22 ++++++++++++++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h
index de0a81a..98a26ce 100644
--- a/arch/arm64/net/bpf_jit.h
+++ b/arch/arm64/net/bpf_jit.h
@@ -110,6 +110,10 @@
 /* Rd = Rn >> shift; signed */
 #define A64_ASR(sf, Rd, Rn, shift) A64_SBFM(sf, Rd, Rn, shift, (sf) ? 63 : 31)
 
+/* Zero extend */
+#define A64_UXTH(sf, Rd, Rn) A64_UBFM(sf, Rd, Rn, 0, 15)
+#define A64_UXTW(sf, Rd, Rn) A64_UBFM(sf, Rd, Rn, 0, 31)
+
 /* Move wide (immediate) */
 #define A64_MOVEW(sf, Rd, imm16, shift, type) \
 	aarch64_insn_gen_movewide(Rd, imm16, shift, \
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index c81ddd4..c047598 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -289,23 +289,41 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 	case BPF_ALU | BPF_END | BPF_FROM_BE:
 #ifdef CONFIG_CPU_BIG_ENDIAN
 		if (BPF_SRC(code) == BPF_FROM_BE)
-			break;
+			goto emit_bswap_uxt;
 #else /* !CONFIG_CPU_BIG_ENDIAN */
 		if (BPF_SRC(code) == BPF_FROM_LE)
-			break;
+			goto emit_bswap_uxt;
 #endif
 		switch (imm) {
 		case 16:
 			emit(A64_REV16(is64, dst, dst), ctx);
+			/* zero-extend 16 bits into 64 bits */
+			emit(A64_UXTH(is64, dst, dst), ctx);
 			break;
 		case 32:
 			emit(A64_REV32(is64, dst, dst), ctx);
+			/* upper 32 bits already cleared */
 			break;
 		case 64:
 			emit(A64_REV64(dst, dst), ctx);
 			break;
 		}
 		break;
+emit_bswap_uxt:
+		switch (imm) {
+		case 16:
+			/* zero-extend 16 bits into 64 bits */
+			emit(A64_UXTH(is64, dst, dst), ctx);
+			break;
+		case 32:
+			/* zero-extend 32 bits into 64 bits */
+			emit(A64_UXTW(is64, dst, dst), ctx);
+			break;
+		case 64:
+			/* nop */
+			break;
+		}
+		break;
 	/* dst = imm */
 	case BPF_ALU | BPF_MOV | BPF_K:
 	case BPF_ALU64 | BPF_MOV | BPF_K:
-- 
2.1.4


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [RFC PATCH] arm64: bpf: fix endianness conversion bugs
@ 2015-06-26  1:39 ` Xi Wang
  0 siblings, 0 replies; 6+ messages in thread
From: Xi Wang @ 2015-06-26  1:39 UTC (permalink / raw)
  To: linux-arm-kernel

Upper bits should be zeroed in endianness conversion:

- even when there's no need to change endianness (i.e., BPF_FROM_BE
  on big endian or BPF_FROM_LE on little endian);

- after rev16.

This patch fixes such bugs by emitting extra instructions to clear
upper bits.

Cc: Zi Shen Lim <zlim.lnx@gmail.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
Signed-off-by: Xi Wang <xi.wang@gmail.com>
---
The current testsuite catches the 16-bit bugs.  I'll send a separate
patch that extends test_bpf to catch the 32-bit ones.
---
 arch/arm64/net/bpf_jit.h      |  4 ++++
 arch/arm64/net/bpf_jit_comp.c | 22 ++++++++++++++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h
index de0a81a..98a26ce 100644
--- a/arch/arm64/net/bpf_jit.h
+++ b/arch/arm64/net/bpf_jit.h
@@ -110,6 +110,10 @@
 /* Rd = Rn >> shift; signed */
 #define A64_ASR(sf, Rd, Rn, shift) A64_SBFM(sf, Rd, Rn, shift, (sf) ? 63 : 31)
 
+/* Zero extend */
+#define A64_UXTH(sf, Rd, Rn) A64_UBFM(sf, Rd, Rn, 0, 15)
+#define A64_UXTW(sf, Rd, Rn) A64_UBFM(sf, Rd, Rn, 0, 31)
+
 /* Move wide (immediate) */
 #define A64_MOVEW(sf, Rd, imm16, shift, type) \
 	aarch64_insn_gen_movewide(Rd, imm16, shift, \
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index c81ddd4..c047598 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -289,23 +289,41 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 	case BPF_ALU | BPF_END | BPF_FROM_BE:
 #ifdef CONFIG_CPU_BIG_ENDIAN
 		if (BPF_SRC(code) == BPF_FROM_BE)
-			break;
+			goto emit_bswap_uxt;
 #else /* !CONFIG_CPU_BIG_ENDIAN */
 		if (BPF_SRC(code) == BPF_FROM_LE)
-			break;
+			goto emit_bswap_uxt;
 #endif
 		switch (imm) {
 		case 16:
 			emit(A64_REV16(is64, dst, dst), ctx);
+			/* zero-extend 16 bits into 64 bits */
+			emit(A64_UXTH(is64, dst, dst), ctx);
 			break;
 		case 32:
 			emit(A64_REV32(is64, dst, dst), ctx);
+			/* upper 32 bits already cleared */
 			break;
 		case 64:
 			emit(A64_REV64(dst, dst), ctx);
 			break;
 		}
 		break;
+emit_bswap_uxt:
+		switch (imm) {
+		case 16:
+			/* zero-extend 16 bits into 64 bits */
+			emit(A64_UXTH(is64, dst, dst), ctx);
+			break;
+		case 32:
+			/* zero-extend 32 bits into 64 bits */
+			emit(A64_UXTW(is64, dst, dst), ctx);
+			break;
+		case 64:
+			/* nop */
+			break;
+		}
+		break;
 	/* dst = imm */
 	case BPF_ALU | BPF_MOV | BPF_K:
 	case BPF_ALU64 | BPF_MOV | BPF_K:
-- 
2.1.4

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [RFC PATCH] arm64: bpf: fix endianness conversion bugs
  2015-06-26  1:39 ` Xi Wang
@ 2015-06-26  8:25   ` Alexei Starovoitov
  -1 siblings, 0 replies; 6+ messages in thread
From: Alexei Starovoitov @ 2015-06-26  8:25 UTC (permalink / raw)
  To: Xi Wang, linux-arm-kernel; +Cc: linux-kernel, Zi Shen Lim

On 6/25/15 6:39 PM, Xi Wang wrote:
> Upper bits should be zeroed in endianness conversion:
>
> - even when there's no need to change endianness (i.e., BPF_FROM_BE
>    on big endian or BPF_FROM_LE on little endian);
>
> - after rev16.
>
> This patch fixes such bugs by emitting extra instructions to clear
> upper bits.
>
> Cc: Zi Shen Lim<zlim.lnx@gmail.com>
> Cc: Alexei Starovoitov<ast@plumgrid.com>
> Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
> Signed-off-by: Xi Wang<xi.wang@gmail.com>

Acked-by: Alexei Starovoitov <ast@plumgrid.com>

> The current testsuite catches the 16-bit bugs.  I'll send a separate
> patch that extends test_bpf to catch the 32-bit ones.

looking forward to it. Thanks.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [RFC PATCH] arm64: bpf: fix endianness conversion bugs
@ 2015-06-26  8:25   ` Alexei Starovoitov
  0 siblings, 0 replies; 6+ messages in thread
From: Alexei Starovoitov @ 2015-06-26  8:25 UTC (permalink / raw)
  To: linux-arm-kernel

On 6/25/15 6:39 PM, Xi Wang wrote:
> Upper bits should be zeroed in endianness conversion:
>
> - even when there's no need to change endianness (i.e., BPF_FROM_BE
>    on big endian or BPF_FROM_LE on little endian);
>
> - after rev16.
>
> This patch fixes such bugs by emitting extra instructions to clear
> upper bits.
>
> Cc: Zi Shen Lim<zlim.lnx@gmail.com>
> Cc: Alexei Starovoitov<ast@plumgrid.com>
> Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
> Signed-off-by: Xi Wang<xi.wang@gmail.com>

Acked-by: Alexei Starovoitov <ast@plumgrid.com>

> The current testsuite catches the 16-bit bugs.  I'll send a separate
> patch that extends test_bpf to catch the 32-bit ones.

looking forward to it. Thanks.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [RFC PATCH] arm64: bpf: fix endianness conversion bugs
  2015-06-26  1:39 ` Xi Wang
@ 2015-06-26 13:17   ` Catalin Marinas
  -1 siblings, 0 replies; 6+ messages in thread
From: Catalin Marinas @ 2015-06-26 13:17 UTC (permalink / raw)
  To: Xi Wang; +Cc: linux-arm-kernel, Zi Shen Lim, linux-kernel, Alexei Starovoitov

On Thu, Jun 25, 2015 at 06:39:15PM -0700, Xi Wang wrote:
> Upper bits should be zeroed in endianness conversion:
> 
> - even when there's no need to change endianness (i.e., BPF_FROM_BE
>   on big endian or BPF_FROM_LE on little endian);
> 
> - after rev16.
> 
> This patch fixes such bugs by emitting extra instructions to clear
> upper bits.
> 
> Cc: Zi Shen Lim <zlim.lnx@gmail.com>
> Cc: Alexei Starovoitov <ast@plumgrid.com>
> Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
> Signed-off-by: Xi Wang <xi.wang@gmail.com>

Applied. Thanks.

-- 
Catalin

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [RFC PATCH] arm64: bpf: fix endianness conversion bugs
@ 2015-06-26 13:17   ` Catalin Marinas
  0 siblings, 0 replies; 6+ messages in thread
From: Catalin Marinas @ 2015-06-26 13:17 UTC (permalink / raw)
  To: linux-arm-kernel

On Thu, Jun 25, 2015 at 06:39:15PM -0700, Xi Wang wrote:
> Upper bits should be zeroed in endianness conversion:
> 
> - even when there's no need to change endianness (i.e., BPF_FROM_BE
>   on big endian or BPF_FROM_LE on little endian);
> 
> - after rev16.
> 
> This patch fixes such bugs by emitting extra instructions to clear
> upper bits.
> 
> Cc: Zi Shen Lim <zlim.lnx@gmail.com>
> Cc: Alexei Starovoitov <ast@plumgrid.com>
> Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
> Signed-off-by: Xi Wang <xi.wang@gmail.com>

Applied. Thanks.

-- 
Catalin

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2015-06-26 13:17 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-06-26  1:39 [RFC PATCH] arm64: bpf: fix endianness conversion bugs Xi Wang
2015-06-26  1:39 ` Xi Wang
2015-06-26  8:25 ` Alexei Starovoitov
2015-06-26  8:25   ` Alexei Starovoitov
2015-06-26 13:17 ` Catalin Marinas
2015-06-26 13:17   ` Catalin Marinas

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