[PATCH powerpc/next 05/17] powerpc64/bpf: Use r12 for constant blinding

Naveen N. Rao naveen.n.rao at linux.vnet.ibm.com
Mon Feb 14 21:41:39 AEDT 2022


In preparation for preserving kernel toc in r2, switch BPF_REG_AX from
r2 to r12. r12 is not used by bpf JIT except during external helper/bpf
calls, or with BPF_NOSPEC. These sequences aren't emitted when
BPF_REG_AX is used for constant blinding and other purposes.

Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
---
 arch/powerpc/net/bpf_jit64.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/net/bpf_jit64.h b/arch/powerpc/net/bpf_jit64.h
index b63b35e45e558c..82cdfee412784a 100644
--- a/arch/powerpc/net/bpf_jit64.h
+++ b/arch/powerpc/net/bpf_jit64.h
@@ -56,7 +56,7 @@ const int b2p[MAX_BPF_JIT_REG + 2] = {
 	/* frame pointer aka BPF_REG_10 */
 	[BPF_REG_FP] = 31,
 	/* eBPF jit internal registers */
-	[BPF_REG_AX] = 2,
+	[BPF_REG_AX] = 12,
 	[TMP_REG_1] = 9,
 	[TMP_REG_2] = 10
 };
-- 
2.35.1



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