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authorDaniel Borkmann <daniel@iogearbox.net>2018-11-26 14:05:38 +0100
committerAlexei Starovoitov <ast@kernel.org>2018-11-26 17:34:24 -0800
commite2c95a61656d29ceaac97b6a975c8a1f26e26f15 (patch)
tree8fb9a3cc00ef0b47edb7428d297bc921b39e1f2f /arch/powerpc/net
parent69500127424cd90ff2cf8191256b2ac3b0a4af56 (diff)
bpf, ppc64: generalize fetching subprog into bpf_jit_get_func_addr
Make fetching of the BPF call address from ppc64 JIT generic. ppc64 was using a slightly different variant rather than through the insns' imm field encoding as the target address would not fit into that space. Therefore, the target subprog number was encoded into the insns' offset and fetched through fp->aux->func[off]->bpf_func instead. Given there are other JITs with this issue and the mechanism of fetching the address is JIT-generic, move it into the core as a helper instead. On the JIT side, we get information on whether the retrieved address is a fixed one, that is, not changing through JIT passes, or a dynamic one. For the former, JITs can optimize their imm emission because this doesn't change jump offsets throughout JIT process. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Sandipan Das <sandipan@linux.ibm.com> Tested-by: Sandipan Das <sandipan@linux.ibm.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/powerpc/net')
-rw-r--r--arch/powerpc/net/bpf_jit_comp64.c57
1 files changed, 38 insertions, 19 deletions
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 50b129785aee..17482f5de3e2 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -166,7 +166,33 @@ static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx)
PPC_BLR();
}
-static void bpf_jit_emit_func_call(u32 *image, struct codegen_context *ctx, u64 func)
+static void bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx,
+ u64 func)
+{
+#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);
+#endif
+ PPC_BLRL();
+}
+
+static void bpf_jit_emit_func_call_rel(u32 *image, struct codegen_context *ctx,
+ u64 func)
{
unsigned int i, ctx_idx = ctx->idx;
@@ -273,7 +299,7 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
{
const struct bpf_insn *insn = fp->insnsi;
int flen = fp->len;
- int i;
+ int i, ret;
/* Start of epilogue code - will only be valid 2nd pass onwards */
u32 exit_addr = addrs[flen];
@@ -284,8 +310,9 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
u32 src_reg = b2p[insn[i].src_reg];
s16 off = insn[i].off;
s32 imm = insn[i].imm;
+ bool func_addr_fixed;
+ u64 func_addr;
u64 imm64;
- u8 *func;
u32 true_cond;
u32 tmp_idx;
@@ -711,23 +738,15 @@ emit_clear:
case BPF_JMP | BPF_CALL:
ctx->seen |= SEEN_FUNC;
- /* bpf function call */
- if (insn[i].src_reg == BPF_PSEUDO_CALL)
- if (!extra_pass)
- func = NULL;
- else if (fp->aux->func && off < fp->aux->func_cnt)
- /* use the subprog id from the off
- * field to lookup the callee address
- */
- func = (u8 *) fp->aux->func[off]->bpf_func;
- else
- return -EINVAL;
- /* kernel helper call */
- else
- func = (u8 *) __bpf_call_base + imm;
-
- bpf_jit_emit_func_call(image, ctx, (u64)func);
+ ret = bpf_jit_get_func_addr(fp, &insn[i], extra_pass,
+ &func_addr, &func_addr_fixed);
+ if (ret < 0)
+ return ret;
+ if (func_addr_fixed)
+ bpf_jit_emit_func_call_hlp(image, ctx, func_addr);
+ else
+ bpf_jit_emit_func_call_rel(image, ctx, func_addr);
/* move return value from r3 to BPF_REG_0 */
PPC_MR(b2p[BPF_REG_0], 3);
break;