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

David Faust david.faust@oracle.com
Tue Jan 18 20:47:14 GMT 2022


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?
Thanks

gcc/ChangeLog:

	* config/bpf/coreout.c (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.c                      | 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.c b/gcc/config/bpf/coreout.c
index f8ca2804207..4ec12ecd305 100644
--- a/gcc/config/bpf/coreout.c
+++ b/gcc/config/bpf/coreout.c
@@ -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 } } */
-- 
2.34.1



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