Re: [PATCH v2] bpf: write CO-RE relocation record size only once

[David Faust via Gcc-patches]

On 1/18/22 13:17, Jose E. Marchesi wrote:

Hi David.

[Changed from v1: Adjust to account for file renaming so patch applies.]

The CO-RE relocation record size should be written only once in the
.BTF.ext section, not once for each section with relocations.

Tested for bpf-unknown-none. OK to install?

This is OK.
Thanks for the patch.

Pushed, thanks

Thanks.

gcc/ChangeLog:

        * config/bpf/coreout.cc (output_btfext_header): Account for
        4-byte record size in core_relo_len.
        (output_btfext_core_sections): Only write record size once.
        * config/bpf/coreout.h (btf_ext_section_header): Delete unused
        member.

gcc/testsuite/ChangeLog:

        * gcc.target/bpf/core-section-1.c: Adjust expected record size
        occurrences.
---
  gcc/config/bpf/coreout.cc                     | 14 +++++++++-----
  gcc/config/bpf/coreout.h                      |  1 -
  gcc/testsuite/gcc.target/bpf/core-section-1.c |  2 +-
  3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/gcc/config/bpf/coreout.cc b/gcc/config/bpf/coreout.cc
index f8ca2804207..4ec12ecd305 100644
--- a/gcc/config/bpf/coreout.cc
+++ b/gcc/config/bpf/coreout.cc
@@ -259,7 +259,7 @@ output_btfext_header (void)
    uint32_t core_relo_off = 0, core_relo_len = 0;

/* Header core_relo_len is the sum total length in bytes of all CO-RE

-     relocation sections.  */
+     relocation sections, plus the 4 byte record size.  */
    size_t i;
    bpf_core_section_ref sec;
    core_relo_len += vec_safe_length (bpf_core_sections)
@@ -269,6 +269,9 @@ output_btfext_header (void)
      core_relo_len +=
        vec_safe_length (sec->relocs) * sizeof (struct btf_ext_reloc);

+ if (core_relo_len)

+    core_relo_len += sizeof (uint32_t);
+
    dw2_asm_output_data (4, func_info_off, "func_info_offset");
    dw2_asm_output_data (4, func_info_len, "func_info_len");

@@ -310,12 +313,13 @@ output_btfext_core_sections (void)

  {
    size_t i;
    bpf_core_section_ref sec;
+
+  /* BTF Ext section info. */
+  dw2_asm_output_data (4, sizeof (struct btf_ext_reloc),
+                      "btfext_core_info_rec_size");
+
    FOR_EACH_VEC_ELT (*bpf_core_sections, i, sec)
      {
-      /* BTF Ext section info. */
-      dw2_asm_output_data (4, sizeof (struct btf_ext_reloc),
-                          "btfext_secinfo_rec_size");
-
        /* Section name offset, refers to the offset of a string with the name 
of
         the section to which these CORE relocations refer, e.g. '.text'.
         The string is buffered in the BTF strings table.  */
diff --git a/gcc/config/bpf/coreout.h b/gcc/config/bpf/coreout.h
index a9d7e364ba3..3c7bdfd8c2f 100644
--- a/gcc/config/bpf/coreout.h
+++ b/gcc/config/bpf/coreout.h
@@ -33,7 +33,6 @@ extern "C"

struct btf_ext_section_header

  {
-  uint32_t kind;
    uint32_t sec_name_off;
    uint32_t num_records;
  };
diff --git a/gcc/testsuite/gcc.target/bpf/core-section-1.c 
b/gcc/testsuite/gcc.target/bpf/core-section-1.c
index 031acd5292e..4f16b087c1a 100644
--- a/gcc/testsuite/gcc.target/bpf/core-section-1.c
+++ b/gcc/testsuite/gcc.target/bpf/core-section-1.c
@@ -35,4 +35,4 @@ int bar_func (struct T *t)
  /* { dg-final { scan-assembler-times "ascii \"foo_sec.0\"\[\t 
\]+\[^\n\]*btf_aux_string" 1 } } */
  /* { dg-final { scan-assembler-times "ascii \"bar_sec.0\"\[\t 
\]+\[^\n\]*btf_aux_string" 1 } } */
  /* { dg-final { scan-assembler-times "bpfcr_type" 2 } } */
-/* { dg-final { scan-assembler-times "btfext_secinfo_rec_size" 2 } } */
+/* { dg-final { scan-assembler-times "btfext_core_info_rec_size" 1 } } */