On 11/03/23 4:05 am, Song Liu wrote:

On Thu, Mar 9, 2023 at 10:03 AM Hari Bathini [off-list ref] wrote:

quoted

Use bpf_jit_binary_pack_alloc in powerpc jit. The jit engine first
writes the program to the rw buffer. When the jit is done, the program
is copied to the final location with bpf_jit_binary_pack_finalize.
With multiple jit_subprogs, bpf_jit_free is called on some subprograms
that haven't got bpf_jit_binary_pack_finalize() yet. Implement custom
bpf_jit_free() like in commit 1d5f82d9dd47 ("bpf, x86: fix freeing of
not-finalized bpf_prog_pack") to call bpf_jit_binary_pack_finalize(),
if necessary. While here, correct the misnomer powerpc64_jit_data to
powerpc_jit_data as it is meant for both ppc32 and ppc64.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
  arch/powerpc/net/bpf_jit.h        |   7 +-
  arch/powerpc/net/bpf_jit_comp.c   | 104 +++++++++++++++++++++---------
  arch/powerpc/net/bpf_jit_comp32.c |   4 +-
  arch/powerpc/net/bpf_jit_comp64.c |   6 +-
  4 files changed, 83 insertions(+), 38 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index d767e39d5645..a8b7480c4d43 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h

@@ -168,15 +168,16 @@ static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i)

  void bpf_jit_init_reg_mapping(struct codegen_context *ctx);
  int bpf_jit_emit_func_call_rel(u32 *image, struct codegen_context *ctx, u64 func);
-int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *ctx,
+int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx,
                        u32 *addrs, int pass, bool extra_pass);
  void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx);
  void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx);
  void bpf_jit_realloc_regs(struct codegen_context *ctx);
  int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr);

-int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct codegen_context *ctx,
-                         int insn_idx, int jmp_off, int dst_reg);
+int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass,
+                         struct codegen_context *ctx, int insn_idx,
+                         int jmp_off, int dst_reg);

  #endif

diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index d1794d9f0154..ece75c829499 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c

@@ -42,10 +42,11 @@ int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg,
         return 0;
  }

-struct powerpc64_jit_data {
-       struct bpf_binary_header *header;
+struct powerpc_jit_data {
+       struct bpf_binary_header *hdr;
+       struct bpf_binary_header *fhdr;
         u32 *addrs;
-       u8 *image;
+       u8 *fimage;
         u32 proglen;
         struct codegen_context ctx;
  };

Some comments about the f- prefix will be helpful. (Yes, I should have done
better job adding comments for the x86 counterpart..)

quoted

@@ -62,15 +63,18 @@ 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 powerpc_jit_data *jit_data;
         struct codegen_context cgctx;
         int pass;
         int flen;
-       struct bpf_binary_header *bpf_hdr;
+       struct bpf_binary_header *fhdr = NULL;
+       struct bpf_binary_header *hdr = NULL;
         struct bpf_prog *org_fp = fp;
         struct bpf_prog *tmp_fp;
         bool bpf_blinded = false;
         bool extra_pass = false;
+       u8 *fimage = NULL;
+       u32 *fcode_base;
         u32 extable_len;
         u32 fixup_len;

@@ -100,9 +104,11 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
         addrs = jit_data->addrs;
         if (addrs) {
                 cgctx = jit_data->ctx;
-               image = jit_data->image;
-               bpf_hdr = jit_data->header;
+               fimage = jit_data->fimage;
+               fhdr = jit_data->fhdr;
                 proglen = jit_data->proglen;
+               hdr = jit_data->hdr;
+               image = (void *)hdr + ((void *)fimage - (void *)fhdr);
                 extra_pass = true;
                 goto skip_init_ctx;
         }

@@ -120,7 +126,7 @@ 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, 0, false)) {
+       if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) {
                 /* We hit something illegal or unsupported. */
                 fp = org_fp;
                 goto out_addrs;

@@ -135,7 +141,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
          */
         if (cgctx.seen & SEEN_TAILCALL || !is_offset_in_branch_range((long)cgctx.idx * 4)) {
                 cgctx.idx = 0;
-               if (bpf_jit_build_body(fp, 0, &cgctx, addrs, 0, false)) {
+               if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) {
                         fp = org_fp;
                         goto out_addrs;
                 }

@@ -157,17 +163,19 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
         proglen = cgctx.idx * 4;
         alloclen = proglen + FUNCTION_DESCR_SIZE + fixup_len + extable_len;

-       bpf_hdr = bpf_jit_binary_alloc(alloclen, &image, 4, bpf_jit_fill_ill_insns);
-       if (!bpf_hdr) {
+       fhdr = bpf_jit_binary_pack_alloc(alloclen, &fimage, 4, &hdr, &image,
+                                             bpf_jit_fill_ill_insns);
+       if (!fhdr) {
                 fp = org_fp;
                 goto out_addrs;
         }

         if (extable_len)
-               fp->aux->extable = (void *)image + FUNCTION_DESCR_SIZE + proglen + fixup_len;
+               fp->aux->extable = (void *)fimage + FUNCTION_DESCR_SIZE + proglen + fixup_len;

  skip_init_ctx:
         code_base = (u32 *)(image + FUNCTION_DESCR_SIZE);
+       fcode_base = (u32 *)(fimage + FUNCTION_DESCR_SIZE);

         /* Code generation passes 1-2 */
         for (pass = 1; pass < 3; pass++) {

@@ -175,8 +183,9 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
                 cgctx.idx = 0;
                 cgctx.alt_exit_addr = 0;
                 bpf_jit_build_prologue(code_base, &cgctx);
-               if (bpf_jit_build_body(fp, code_base, &cgctx, addrs, pass, extra_pass)) {
-                       bpf_jit_binary_free(bpf_hdr);
+               if (bpf_jit_build_body(fp, code_base, fcode_base, &cgctx, addrs, pass, extra_pass)) {
+                       bpf_arch_text_copy(&fhdr->size, &hdr->size, sizeof(hdr->size));
+                       bpf_jit_binary_pack_free(fhdr, hdr);
                         fp = org_fp;
                         goto out_addrs;
                 }

@@ -192,21 +201,23 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
                  * Note that we output the base address of the code_base
                  * rather than image, since opcodes are in code_base.
                  */

Maybe update the comment above with fcode_base to avoid
confusion.

quoted

-               bpf_jit_dump(flen, proglen, pass, code_base);
+               bpf_jit_dump(flen, proglen, pass, fcode_base);

  #ifdef CONFIG_PPC64_ELF_ABI_V1
         /* Function descriptor nastiness: Address + TOC */
-       ((u64 *)image)[0] = (u64)code_base;
+       ((u64 *)image)[0] = (u64)fcode_base;
         ((u64 *)image)[1] = local_paca->kernel_toc;
  #endif

-       fp->bpf_func = (void *)image;
+       fp->bpf_func = (void *)fimage;
         fp->jited = 1;
         fp->jited_len = proglen + FUNCTION_DESCR_SIZE;

-       bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + bpf_hdr->size);
         if (!fp->is_func || extra_pass) {
-               bpf_jit_binary_lock_ro(bpf_hdr);
+               if (bpf_jit_binary_pack_finalize(fp, fhdr, hdr)) {
+                       fp = org_fp;
+                       goto out_addrs;
+               }
                 bpf_prog_fill_jited_linfo(fp, addrs);
  out_addrs:
                 kfree(addrs);

@@ -216,8 +227,9 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
                 jit_data->addrs = addrs;
                 jit_data->ctx = cgctx;
                 jit_data->proglen = proglen;
-               jit_data->image = image;
-               jit_data->header = bpf_hdr;
+               jit_data->fimage = fimage;
+               jit_data->fhdr = fhdr;
+               jit_data->hdr = hdr;
         }

  out:

@@ -231,12 +243,13 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
   * The caller should check for (BPF_MODE(code) == BPF_PROBE_MEM) before calling
   * this function, as this only applies to BPF_PROBE_MEM, for now.
   */
-int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct codegen_context *ctx,
-                         int insn_idx, int jmp_off, int dst_reg)
+int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass,
+                         struct codegen_context *ctx, int insn_idx, int jmp_off,
+                         int dst_reg)
  {
         off_t offset;
         unsigned long pc;
-       struct exception_table_entry *ex;
+       struct exception_table_entry *ex, *ex_entry;
         u32 *fixup;

         /* Populate extable entries only in the last pass */

@@ -247,9 +260,16 @@ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct code
             WARN_ON_ONCE(ctx->exentry_idx >= fp->aux->num_exentries))
                 return -EINVAL;

+       /*
+        * Program is firt written to image before copying to the

s/firt/first/

quoted

+        * final location (fimage). Accordingly, update in the image first.
+        * As all offsets used are relative, copying as is to the
+        * final location should be alright.
+        */
         pc = (unsigned long)&image[insn_idx];
+       ex = (void *)fp->aux->extable - (void *)fimage + (void *)image;

-       fixup = (void *)fp->aux->extable -
+       fixup = (void *)ex -
                 (fp->aux->num_exentries * BPF_FIXUP_LEN * 4) +
                 (ctx->exentry_idx * BPF_FIXUP_LEN * 4);

@@ -260,17 +280,17 @@ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct code
         fixup[BPF_FIXUP_LEN - 1] =
                 PPC_RAW_BRANCH((long)(pc + jmp_off) - (long)&fixup[BPF_FIXUP_LEN - 1]);

-       ex = &fp->aux->extable[ctx->exentry_idx];
+       ex_entry = &ex[ctx->exentry_idx];

-       offset = pc - (long)&ex->insn;
+       offset = pc - (long)&ex_entry->insn;
         if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
                 return -ERANGE;
-       ex->insn = offset;
+       ex_entry->insn = offset;

-       offset = (long)fixup - (long)&ex->fixup;
+       offset = (long)fixup - (long)&ex_entry->fixup;
         if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
                 return -ERANGE;
-       ex->fixup = offset;
+       ex_entry->fixup = offset;

         ctx->exentry_idx++;
         return 0;

@@ -308,3 +328,27 @@ int bpf_arch_text_invalidate(void *dst, size_t len)

         return ret;
  }
+
+void bpf_jit_free(struct bpf_prog *fp)
+{
+       if (fp->jited) {
+               struct powerpc_jit_data *jit_data = fp->aux->jit_data;
+               struct bpf_binary_header *hdr;
+
+               /*
+                * If we fail the final pass of JIT (from jit_subprogs),
+                * the program may not be finalized yet. Call finalize here
+                * before freeing it.
+                */
+               if (jit_data) {
+                       bpf_jit_binary_pack_finalize(fp, jit_data->fhdr, jit_data->hdr);

I just realized x86 is the same. But I think we only need the following
here?

bpf_arch_text_copy(&jit_data->fhdr->size, &jit_data->hdr->size,
sizeof(jit_data->hdr->size));

Right?

Thanks for reviewing.
Better off with bpf_jit_binary_pack_finalize, probably?
Kept it that way for v3. Posted v3. Please review.

Thanks
Hari