On 3/13/24 07:24, Cupertino Miranda wrote:
> Although part of all CO-RE relocation data, type based relocations do
> not require an access string.
> Initial implementation defined it as an empty string.
> On the other hand, libbpf when parsing the CO-RE relocations verifies
> that those strings would contain "0", otherwise reports an error.
> This patch makes GCC compliant with libbpf expectations.
OK, thanks.
>
> gcc/Changelog:
> * config/bpf/btfext-out.cc (cpf_core_reloc_add): Correct for new code.
> Add assert to validate the string is set.
> * config/bpf/core-builtins.cc (cr_final): Make string struct
> field as const.
> (process_enum_value): Correct for field type change.
> (process_type): Set access string to "0".
>
> gcc/testsuite/ChangeLog:
> * gcc.target/bpf/core-builtin-type-based.c: Correct.
> * gcc.target/bpf/core-builtin-type-id.c: Correct.
> ---
> gcc/config/bpf/btfext-out.cc | 5 +++--
> gcc/config/bpf/core-builtins.cc | 10 ++++++----
> gcc/testsuite/gcc.target/bpf/core-builtin-type-based.c | 1 +
> gcc/testsuite/gcc.target/bpf/core-builtin-type-id.c | 1 +
> 4 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/config/bpf/btfext-out.cc b/gcc/config/bpf/btfext-out.cc
> index 57c0dc323812..ff1fd0739f1e 100644
> --- a/gcc/config/bpf/btfext-out.cc
> +++ b/gcc/config/bpf/btfext-out.cc
> @@ -299,8 +299,9 @@ bpf_core_reloc_add (const tree type, const char *
> section_name,
>
> /* Buffer the access string in the auxiliary strtab. */
> bpfcr->bpfcr_astr_off = 0;
> - if (accessor != NULL)
> - bpfcr->bpfcr_astr_off = btf_ext_add_string (accessor);
> + gcc_assert (accessor != NULL);
> + bpfcr->bpfcr_astr_off = btf_ext_add_string (accessor);
> +
> bpfcr->bpfcr_type = get_btf_id (ctf_lookup_tree_type (ctfc, type));
> bpfcr->bpfcr_insn_label = label;
> bpfcr->bpfcr_kind = kind;
> diff --git a/gcc/config/bpf/core-builtins.cc b/gcc/config/bpf/core-builtins.cc
> index 4256fea15e49..70b14e48e6e5 100644
> --- a/gcc/config/bpf/core-builtins.cc
> +++ b/gcc/config/bpf/core-builtins.cc
> @@ -205,7 +205,7 @@ struct cr_local
> /* Core Relocation Final data */
> struct cr_final
> {
> - char *str;
> + const char *str;
> tree type;
> enum btf_core_reloc_kind kind;
> };
> @@ -868,8 +868,10 @@ process_enum_value (struct cr_builtins *data)
> {
> if (TREE_VALUE (l) == expr)
> {
> - ret.str = (char *) ggc_alloc_atomic ((index / 10) + 1);
> - sprintf (ret.str, "%d", index);
> + char *tmp = (char *) ggc_alloc_atomic ((index / 10) + 1);
> + sprintf (tmp, "%d", index);
> + ret.str = (const char *) tmp;
> +
> break;
> }
> index++;
> @@ -987,7 +989,7 @@ process_type (struct cr_builtins *data)
> || data->kind == BPF_RELO_TYPE_MATCHES);
>
> struct cr_final ret;
> - ret.str = NULL;
> + ret.str = ggc_strdup ("0");
> ret.type = data->type;
> ret.kind = data->kind;
>
> diff --git a/gcc/testsuite/gcc.target/bpf/core-builtin-type-based.c
> b/gcc/testsuite/gcc.target/bpf/core-builtin-type-based.c
> index 74a8d5a14d9d..9d818133c084 100644
> --- a/gcc/testsuite/gcc.target/bpf/core-builtin-type-based.c
> +++ b/gcc/testsuite/gcc.target/bpf/core-builtin-type-based.c
> @@ -56,3 +56,4 @@ int foo(void *data)
> /* { dg-final { scan-assembler-times "0x8\[\t \]+\[^\n\]*bpfcr_kind" 13 } }
> BPF_TYPE_EXISTS */
> /* { dg-final { scan-assembler-times "0x9\[\t \]+\[^\n\]*bpfcr_kind" 11 } }
> BPF_TYPE_SIZE */
> /* { dg-final { scan-assembler-times "0xc\[\t \]+\[^\n\]*bpfcr_kind" 13 } }
> BPF_TYPE_MATCHES */
> +/* { dg-final { scan-assembler-times "bpfcr_astr_off \[(\"\]+0\[(\"\]+" 37 }
> } */
> diff --git a/gcc/testsuite/gcc.target/bpf/core-builtin-type-id.c
> b/gcc/testsuite/gcc.target/bpf/core-builtin-type-id.c
> index 4b23288eac08..9576b91bc940 100644
> --- a/gcc/testsuite/gcc.target/bpf/core-builtin-type-id.c
> +++ b/gcc/testsuite/gcc.target/bpf/core-builtin-type-id.c
> @@ -38,3 +38,4 @@ int foo(void *data)
> /* { dg-final { scan-assembler-times "0\[\t \]+\[^\n\]*bpfcr_type" 0 {
> xfail *-*-* } } } */
> /* { dg-final { scan-assembler-times "0x6\[\t \]+\[^\n\]*bpfcr_kind" 13 } }
> BPF_TYPE_ID_LOCAL */
> /* { dg-final { scan-assembler-times "0x7\[\t \]+\[^\n\]*bpfcr_kind" 7 } }
> BPF_TYPE_ID_TARGET */
> +/* { dg-final { scan-assembler-times "bpfcr_astr_off \[(\"\]+0\[(\"\]+" 20 }
> } */
