@@ -256,7 +256,7 @@ static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32
/* Assemble the body code between the prologue & epilogue */
static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
struct codegen_context *ctx,
- u32 *addrs)
+ u32 *addrs, bool extra_pass)
{
const struct bpf_insn *insn = fp->insnsi;
int flen = fp->len;
@@ -712,11 +712,23 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
break;
/*
- * Call kernel helper
+ * Call kernel helper or bpf function
*/
case BPF_JMP | BPF_CALL:
ctx->seen |= SEEN_FUNC;
- func = (u8 *) __bpf_call_base + imm;
+
+ /* bpf function call */
+ if (insn[i].src_reg == BPF_PSEUDO_CALL && extra_pass)
+ 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);
@@ -864,6 +876,14 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
return 0;
}
+struct powerpc64_jit_data {
+ struct bpf_binary_header *header;
+ u32 *addrs;
+ u8 *image;
+ u32 proglen;
+ struct codegen_context ctx;
+};
+
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
{
u32 proglen;
@@ -871,6 +891,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
u8 *image = NULL;
u32 *code_base;
u32 *addrs;
+ struct powerpc64_jit_data *jit_data;
struct codegen_context cgctx;
int pass;
int flen;
@@ -878,6 +899,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
struct bpf_prog *org_fp = fp;
struct bpf_prog *tmp_fp;
bool bpf_blinded = false;
+ bool extra_pass = false;
if (!fp->jit_requested)
return org_fp;
@@ -891,7 +913,28 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
fp = tmp_fp;
}
+ jit_data = fp->aux->jit_data;
+ if (!jit_data) {
+ jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
+ if (!jit_data) {
+ fp = org_fp;
+ goto out;
+ }
+ fp->aux->jit_data = jit_data;
+ }
+
flen = fp->len;
+ addrs = jit_data->addrs;
+ if (addrs) {
+ cgctx = jit_data->ctx;
+ image = jit_data->image;
+ bpf_hdr = jit_data->header;
+ proglen = jit_data->proglen;
+ alloclen = proglen + FUNCTION_DESCR_SIZE;
+ extra_pass = true;
+ goto skip_init_ctx;
+ }
+
addrs = kzalloc((flen+1) * sizeof(*addrs), GFP_KERNEL);
if (addrs == NULL) {
fp = org_fp;
@@ -904,10 +947,10 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
cgctx.stack_size = round_up(fp->aux->stack_depth, 16);
/* Scouting faux-generate pass 0 */
- if (bpf_jit_build_body(fp, 0, &cgctx, addrs)) {
+ if (bpf_jit_build_body(fp, 0, &cgctx, addrs, false)) {
/* We hit something illegal or unsupported. */
fp = org_fp;
- goto out;
+ goto out_addrs;
}
/*
@@ -925,9 +968,10 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
bpf_jit_fill_ill_insns);
if (!bpf_hdr) {
fp = org_fp;
- goto out;
+ goto out_addrs;
}
+skip_init_ctx:
code_base = (u32 *)(image + FUNCTION_DESCR_SIZE);
/* Code generation passes 1-2 */
@@ -935,7 +979,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
/* Now build the prologue, body code & epilogue for real. */
cgctx.idx = 0;
bpf_jit_build_prologue(code_base, &cgctx);
- bpf_jit_build_body(fp, code_base, &cgctx, addrs);
+ bpf_jit_build_body(fp, code_base, &cgctx, addrs, extra_pass);
bpf_jit_build_epilogue(code_base, &cgctx);
if (bpf_jit_enable > 1)
@@ -956,15 +1000,30 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
((u64 *)image)[1] = local_paca->kernel_toc;
#endif
+ bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + (bpf_hdr->pages * PAGE_SIZE));
+
+ if (!fp->is_func || extra_pass) {
+ bpf_jit_binary_lock_ro(bpf_hdr);
+ } else {
+ jit_data->addrs = addrs;
+ jit_data->ctx = cgctx;
+ jit_data->proglen = proglen;
+ jit_data->image = image;
+ jit_data->header = bpf_hdr;
+ }
+
fp->bpf_func = (void *)image;
fp->jited = 1;
fp->jited_len = alloclen;
- bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + (bpf_hdr->pages * PAGE_SIZE));
+ if (!fp->is_func || extra_pass) {
+out_addrs:
+ kfree(addrs);
+ kfree(jit_data);
+ fp->aux->jit_data = NULL;
+ }
out:
- kfree(addrs);
-
if (bpf_blinded)
bpf_jit_prog_release_other(fp, fp == org_fp ? tmp_fp : org_fp);
This adds support for bpf-to-bpf function calls in the powerpc64 JIT compiler. The JIT compiler converts the bpf call instructions to native branch instructions. After a round of the usual passes, the start addresses of the JITed images for the callee functions are known. Finally, to fixup the branch target addresses, we need to perform an extra pass. Because of the address range in which JITed images are allocated on powerpc64, the offsets of the start addresses of these images from __bpf_call_base are as large as 64 bits. So, for a function call, we cannot use the imm field of the instruction to determine the callee's address. Instead, we use the alternative method of getting it from the list of function addresses in the auxillary data of the caller by using the off field as an index. Signed-off-by: Sandipan Das <sandipan@linux.vnet.ibm.com> --- v3: Mention briefly about why the offsets are large. v2: Use the off field of the instruction as an index for aux->func to determine the start address of a callee function. --- arch/powerpc/net/bpf_jit_comp64.c | 79 ++++++++++++++++++++++++++++++++++----- 1 file changed, 69 insertions(+), 10 deletions(-)