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From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Johan Almbladh <johan.almbladh@anyfinetworks.com>
Cc: bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 6/9] powerpc/bpf: Fix BPF_SUB when imm == 0x80000000
Date: Sat,  2 Oct 2021 02:44:52 +0530	[thread overview]
Message-ID: <1912a409447071f46ac6cc957ce8edea0e5232b7.1633104510.git.naveen.n.rao@linux.vnet.ibm.com> (raw)
In-Reply-To: <cover.1633104510.git.naveen.n.rao@linux.vnet.ibm.com>

We aren't handling subtraction involving an immediate value of
0x80000000 properly. Fix the same.

Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/net/bpf_jit_comp64.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index ffb7a2877a8469..4641a50e82d50d 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -333,15 +333,15 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 		case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
 		case BPF_ALU64 | BPF_ADD | BPF_K: /* dst += imm */
 		case BPF_ALU64 | BPF_SUB | BPF_K: /* dst -= imm */
-			if (BPF_OP(code) == BPF_SUB)
-				imm = -imm;
-			if (imm) {
-				if (imm >= -32768 && imm < 32768)
-					EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));
-				else {
-					PPC_LI32(b2p[TMP_REG_1], imm);
+			if (imm > -32768 && imm < 32768) {
+				EMIT(PPC_RAW_ADDI(dst_reg, dst_reg,
+					BPF_OP(code) == BPF_SUB ? IMM_L(-imm) : IMM_L(imm)));
+			} else {
+				PPC_LI32(b2p[TMP_REG_1], imm);
+				if (BPF_OP(code) == BPF_SUB)
+					EMIT(PPC_RAW_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]));
+				else
 					EMIT(PPC_RAW_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]));
-				}
 			}
 			goto bpf_alu32_trunc;
 		case BPF_ALU | BPF_MUL | BPF_X: /* (u32) dst *= (u32) src */
-- 
2.33.0


  parent reply	other threads:[~2021-10-01 21:21 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-01 21:14 [PATCH 0/9] powerpc/bpf: Various fixes Naveen N. Rao
2021-10-01 21:14 ` [PATCH 1/9] powerpc/lib: Add helper to check if offset is within conditional branch range Naveen N. Rao
2021-10-01 21:37   ` Song Liu
2021-10-04 18:02     ` Naveen N. Rao
2021-10-03  7:50   ` Christophe Leroy
2021-10-04 18:03     ` Naveen N. Rao
2021-10-01 21:14 ` [PATCH 2/9] powerpc/bpf: Validate branch ranges Naveen N. Rao
2021-10-01 21:45   ` Song Liu
2021-10-02 17:29   ` Johan Almbladh
2021-10-03  7:54   ` Christophe Leroy
2021-10-04 18:11     ` Naveen N. Rao
2021-10-01 21:14 ` [PATCH 3/9] powerpc/bpf: Remove unused SEEN_STACK Naveen N. Rao
2021-10-01 21:47   ` Song Liu
2021-10-02 17:30   ` Johan Almbladh
2021-10-03  7:55   ` Christophe Leroy
2021-10-04 18:11     ` Naveen N. Rao
2021-10-05  5:50       ` Christophe Leroy
2021-10-05 20:22         ` Naveen N. Rao
2021-10-01 21:14 ` [PATCH 4/9] powerpc/bpf: Handle large branch ranges with BPF_EXIT Naveen N. Rao
2021-10-01 21:53   ` Song Liu
2021-10-02 17:31   ` Johan Almbladh
2021-10-03  7:59   ` Christophe Leroy
2021-10-04 18:24     ` Naveen N. Rao
2021-10-05  5:46       ` Christophe Leroy
2022-01-07 11:46         ` Naveen N. Rao
2021-10-01 21:14 ` [PATCH 5/9] powerpc/bpf: Fix BPF_MOD when imm == 1 Naveen N. Rao
2021-10-01 21:55   ` Song Liu
2021-10-02 17:32   ` Johan Almbladh
2021-10-01 21:14 ` Naveen N. Rao [this message]
2021-10-01 22:01   ` [PATCH 6/9] powerpc/bpf: Fix BPF_SUB when imm == 0x80000000 Song Liu
2021-10-02 17:33   ` Johan Almbladh
2021-10-03  8:07   ` Christophe Leroy
2021-10-04 18:18     ` Naveen N. Rao
2021-10-05  5:40       ` Christophe Leroy
2021-10-01 21:14 ` [PATCH 7/9] powerpc/bpf: Limit 'ldbrx' to processors compliant with ISA v2.06 Naveen N. Rao
2021-10-02 17:35   ` Johan Almbladh
2021-10-01 21:14 ` [PATCH 8/9] powerpc/security: Add a helper to query stf_barrier type Naveen N. Rao
2021-10-01 21:14 ` [PATCH 9/9] powerpc/bpf: Emit stf barrier instruction sequences for BPF_NOSPEC Naveen N. Rao
2021-10-02 17:41 ` [PATCH 0/9] powerpc/bpf: Various fixes Johan Almbladh
2021-10-04 18:19   ` Naveen N. Rao

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