diff options
| -rw-r--r-- | arch/powerpc/net/bpf_jit_comp64.c | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 1bdb1aff0619..e4582744a31d 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -167,25 +167,37 @@ static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) static void bpf_jit_emit_func_call(u32 *image, struct codegen_context *ctx, u64 func) { + unsigned int i, ctx_idx = ctx->idx; + + /* Load function address into r12 */ + PPC_LI64(12, func); + + /* For bpf-to-bpf function calls, the callee's address is unknown + * until the last extra pass. As seen above, we use PPC_LI64() to + * load the callee's address, but this may optimize the number of + * instructions required based on the nature of the address. + * + * Since we don't want the number of instructions emitted to change, + * we pad the optimized PPC_LI64() call with NOPs to guarantee that + * we always have a five-instruction sequence, which is the maximum + * that PPC_LI64() can emit. + */ + for (i = ctx->idx - ctx_idx; i < 5; i++) + PPC_NOP(); + #ifdef PPC64_ELF_ABI_v1 - /* func points to the function descriptor */ - PPC_LI64(b2p[TMP_REG_2], func); - /* Load actual entry point from function descriptor */ - PPC_BPF_LL(b2p[TMP_REG_1], b2p[TMP_REG_2], 0); - /* ... and move it to LR */ - PPC_MTLR(b2p[TMP_REG_1]); /* * Load TOC from function descriptor at offset 8. * We can clobber r2 since we get called through a * function pointer (so caller will save/restore r2) * and since we don't use a TOC ourself. */ - PPC_BPF_LL(2, b2p[TMP_REG_2], 8); -#else - /* We can clobber r12 */ - PPC_FUNC_ADDR(12, func); - PPC_MTLR(12); + PPC_BPF_LL(2, 12, 8); + /* Load actual entry point from function descriptor */ + PPC_BPF_LL(12, 12, 0); #endif + + PPC_MTLR(12); PPC_BLRL(); } |