linux-kernel - [RFC PATCH v1 2/7] powerpc/bpf: Change register numbering for bpf_set/is_seen

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Date:   Wed, 16 Dec 2020 10:07:32 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, ast@...nel.org,
        daniel@...earbox.net, andrii@...nel.org, kafai@...com,
        songliubraving@...com, yhs@...com, john.fastabend@...il.com,
        kpsingh@...omium.org, naveen.n.rao@...ux.ibm.com,
        sandipan@...ux.ibm.com
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org
Subject: [RFC PATCH v1 2/7] powerpc/bpf: Change register numbering for
 bpf_set/is_seen_register()

Instead of using BPF register number as input in functions
bpf_set_seen_register() and bpf_is_seen_register(), use
CPU register number directly.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 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 022103c6a201..26a836a904f5 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -31,12 +31,12 @@ static inline void bpf_flush_icache(void *start, void *end)
 
 static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
 {
-	return (ctx->seen & (1 << (31 - b2p[i])));
+	return ctx->seen & (1 << (31 - i));
 }
 
 static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
 {
-	ctx->seen |= (1 << (31 - b2p[i]));
+	ctx->seen |= 1 << (31 - i);
 }
 
 static inline bool bpf_has_stack_frame(struct codegen_context *ctx)
@@ -47,7 +47,7 @@ static inline bool bpf_has_stack_frame(struct codegen_context *ctx)
 	 * - the bpf program uses its stack area
 	 * The latter condition is deduced from the usage of BPF_REG_FP
 	 */
-	return ctx->seen & SEEN_FUNC || bpf_is_seen_register(ctx, BPF_REG_FP);
+	return ctx->seen & SEEN_FUNC || bpf_is_seen_register(ctx, b2p[BPF_REG_FP]);
 }
 
 /*
@@ -124,11 +124,11 @@ static void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
 	 * in the protected zone below the previous stack frame
 	 */
 	for (i = BPF_REG_6; i <= BPF_REG_10; i++)
-		if (bpf_is_seen_register(ctx, i))
+		if (bpf_is_seen_register(ctx, b2p[i]))
 			PPC_BPF_STL(b2p[i], 1, bpf_jit_stack_offsetof(ctx, b2p[i]));
 
 	/* Setup frame pointer to point to the bpf stack area */
-	if (bpf_is_seen_register(ctx, BPF_REG_FP))
+	if (bpf_is_seen_register(ctx, b2p[BPF_REG_FP]))
 		EMIT(PPC_RAW_ADDI(b2p[BPF_REG_FP], 1,
 				STACK_FRAME_MIN_SIZE + ctx->stack_size));
 }
@@ -139,7 +139,7 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx
 
 	/* Restore NVRs */
 	for (i = BPF_REG_6; i <= BPF_REG_10; i++)
-		if (bpf_is_seen_register(ctx, i))
+		if (bpf_is_seen_register(ctx, b2p[i]))
 			PPC_BPF_LL(b2p[i], 1, bpf_jit_stack_offsetof(ctx, b2p[i]));
 
 	/* Tear down our stack frame */
@@ -330,9 +330,9 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
 		 * any issues.
 		 */
 		if (dst_reg >= BPF_PPC_NVR_MIN && dst_reg < 32)
-			bpf_set_seen_register(ctx, insn[i].dst_reg);
+			bpf_set_seen_register(ctx, dst_reg);
 		if (src_reg >= BPF_PPC_NVR_MIN && src_reg < 32)
-			bpf_set_seen_register(ctx, insn[i].src_reg);
+			bpf_set_seen_register(ctx, src_reg);
 
 		switch (code) {
 		/*
-- 
2.25.0