netdev - [RFC PATCH v1 5/7] powerpc/bpf: Change values of SEEN

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Date:   Wed, 16 Dec 2020 10:07:35 +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 5/7] powerpc/bpf: Change values of SEEN_ flags

Because PPC32 will use more non volatile registers,
move SEEN_ flags to positions 0-2 which corresponds to special
registers.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/net/bpf_jit.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index b34abfce15a6..fb4656986fb9 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h
@@ -108,18 +108,18 @@ static inline bool is_nearbranch(int offset)
 #define COND_LT		(CR0_LT | COND_CMP_TRUE)
 #define COND_LE		(CR0_GT | COND_CMP_FALSE)
 
-#define SEEN_FUNC	0x1000 /* might call external helpers */
-#define SEEN_STACK	0x2000 /* uses BPF stack */
-#define SEEN_TAILCALL	0x4000 /* uses tail calls */
+#define SEEN_FUNC	0x20000000 /* might call external helpers */
+#define SEEN_STACK	0x40000000 /* uses BPF stack */
+#define SEEN_TAILCALL	0x80000000 /* uses tail calls */
 
 struct codegen_context {
 	/*
 	 * This is used to track register usage as well
 	 * as calls to external helpers.
 	 * - register usage is tracked with corresponding
-	 *   bits (r3-r10 and r27-r31)
+	 *   bits (r3-r31)
 	 * - rest of the bits can be used to track other
-	 *   things -- for now, we use bits 16 to 23
+	 *   things -- for now, we use bits 0 to 2
 	 *   encoded in SEEN_* macros above
 	 */
 	unsigned int seen;
-- 
2.25.0