Hi Cuper.
Thanks for the patch.
> This patch adds line_info debug information support to .BTF.ext
> sections.
> Line info information is used by the BPF verifier to improve error
> reporting and give more precise source core referenced errors.
>
> gcc/Changelog:
> * config/bpf/bpf-protos.h (bpf_output_call): Change prototype.
> * config/bpf/bpf.cc (bpf_output_call): Change to adapt operands
> and return
> the instruction template instead of emmidiatelly emit asm and
> not allow proper final expected execution flow.
> (bpf_output_line_info): Add function to introduce line info
> entries in respective structures
> (bpf_asm_out_unwind_emit): Add function as hook to
> TARGET_ASM_UNWIND_EMIT. This hook is called before any
> instruction is emitted.
Is it actually necessary to emit a label (plus .BTF.ext entry) for every
instruction?
> * config/bpf/bpf.md: Change calls to bpf_output_call.
> * config/bpf/btfext-out.cc (struct btf_ext_lineinfo): Add fields
> to struct.
> (bpf_create_lineinfo, btf_add_line_info_for): Add support
> function to insert line_info data in respective structures.
> (output_btfext_line_info): Function to emit line_info data in
> .BTF.ext section.
> (btf_ext_output): Call output_btfext_line_info.
> * config/bpf/btfext-out.h: Add prototype for
> btf_add_line_info_for.
> ---
> gcc/config/bpf/bpf-protos.h | 2 +-
> gcc/config/bpf/bpf.cc | 103 ++++++++++++++---
> gcc/config/bpf/bpf.md | 4 +-
> gcc/config/bpf/btfext-out.cc | 108 +++++++++++++++++-
> gcc/config/bpf/btfext-out.h | 4 +
> .../gcc.target/bpf/btfext-funcinfo.c | 3 +-
> 6 files changed, 203 insertions(+), 21 deletions(-)
>
> diff --git a/gcc/config/bpf/bpf-protos.h b/gcc/config/bpf/bpf-protos.h
> index b4866d34209..ddaca50af69 100644
> --- a/gcc/config/bpf/bpf-protos.h
> +++ b/gcc/config/bpf/bpf-protos.h
> @@ -23,7 +23,7 @@ along with GCC; see the file COPYING3. If not see
> /* Routines implemented in bpf.cc. */
>
> extern HOST_WIDE_INT bpf_initial_elimination_offset (int, int);
> -extern const char *bpf_output_call (rtx);
> +extern const char *bpf_output_call (const char *templ, rtx *, int
> target_index);
> extern void bpf_target_macros (cpp_reader *);
> extern void bpf_print_operand (FILE *, rtx, int);
> extern void bpf_print_operand_address (FILE *, rtx);
> diff --git a/gcc/config/bpf/bpf.cc b/gcc/config/bpf/bpf.cc
> index d9141dd625a..f1a8eb8d62c 100644
> --- a/gcc/config/bpf/bpf.cc
> +++ b/gcc/config/bpf/bpf.cc
> @@ -754,14 +754,12 @@ bpf_output_destructor (rtx symbol, int priority
> ATTRIBUTE_UNUSED)
> bpf.md. */
>
> const char *
> -bpf_output_call (rtx target)
> +bpf_output_call (const char *templ, rtx *operands, int target_index)
> {
> - rtx xops[1];
> -
> + rtx target = operands[target_index];
> switch (GET_CODE (target))
> {
> case CONST_INT:
> - output_asm_insn ("call\t%0", &target);
> break;
> case SYMBOL_REF:
> {
> @@ -774,26 +772,20 @@ bpf_output_call (rtx target)
> {
> tree attr_args = TREE_VALUE (attr);
>
> - xops[0] = GEN_INT (TREE_INT_CST_LOW (TREE_VALUE (attr_args)));
> - output_asm_insn ("call\t%0", xops);
> - }
> - else
> - output_asm_insn ("call\t%0", &target);
> + operands[target_index] = GEN_INT (TREE_INT_CST_LOW (TREE_VALUE
> (attr_args)));
>
> + }
> break;
> }
> default:
> - if (TARGET_XBPF)
> - output_asm_insn ("call\t%0", &target);
> - else
> + if (!TARGET_XBPF)
> {
> error ("indirect call in function, which are not supported by eBPF");
> - output_asm_insn ("call 0", NULL);
> + operands[target_index] = GEN_INT (0);
> }
> break;
> }
> -
> - return "";
> + return templ;
> }
>
> const char *
> @@ -1144,6 +1136,87 @@ bpf_debug_unwind_info ()
> #undef TARGET_DEBUG_UNWIND_INFO
> #define TARGET_DEBUG_UNWIND_INFO bpf_debug_unwind_info
>
> +/* Create a BTF.ext line_info entry. */
> +
> +static void
> +bpf_output_line_info (FILE *asm_out_file, rtx_insn *insn)
> +{
> + static unsigned int line_info_label = 1;
> + static tree cfun_decl = NULL_TREE;
> + static bool func_start_added = false;
> + const char *label = NULL;
> + unsigned int loc = 0;
> + const char *filename = NULL;
> + unsigned int line = 0;
> + unsigned int column = 0;
> +
> + if(!btf_debuginfo_p ())
> + return;
I think it would be better to put this guard in bpf_asm_out_unwind_emit
instead of bpf_output_line_info.
> +
> + gcc_assert (insn != NULL_RTX);
> +
> + if (current_function_decl != cfun_decl
> + && GET_CODE (insn) == NOTE)
> + {
> + label = current_function_func_begin_label;
> + loc = DECL_SOURCE_LOCATION (current_function_decl);
> + filename = LOCATION_FILE (loc);
> + line = LOCATION_LINE (loc);
> + column = LOCATION_COLUMN (loc);
> + func_start_added = true;
> + }
> + else
> + {
> + if (GET_CODE (insn) == NOTE)
> + return;
> +
> + /* Already added a label for this location. This might not be fully
> + acurate but it is better then adding 2 entries on the same location,
> + which is imcompatible with the verifier expectations. */
> + if (func_start_added == true)
> + {
> + func_start_added = false;
> + return;
> + }
> +
> + loc = INSN_LOCATION (insn);
> + filename = LOCATION_FILE (loc);
> + line = LOCATION_LINE (loc);
> + column = LOCATION_COLUMN (loc);
> +
> + if (filename == NULL || line == 0)
> + return;
> +
> + char tmp_label[25];
> + sprintf(tmp_label, "LI%u", line_info_label);
> + ASM_OUTPUT_LABEL (asm_out_file, tmp_label);
> + line_info_label += 1;
> + label = CONST_CAST (char *, ggc_strdup (tmp_label));
> + }
> +
> + cfun_decl = current_function_decl;
> +
> + if (filename != NULL && line != 0)
> + btf_add_line_info_for (label, filename, line, column);
> +}
> +
> +
> +/* This hook is defined as a way for BPF target to create a label before each
> + * emitted instruction and emit line_info information. This data is later
> output
> + * in .BTF.ext section.
> + * This approach expects TARGET_EMIT_BEFORE_INSN to be returing TRUE as
> + * this function needs to be called before the instruction is emitted.
> Current
> + * default behaviour returns TRUE and the hook is left undefined. */
> +
> +static void
> +bpf_asm_out_unwind_emit (FILE *asm_out_file, rtx_insn *insn)
> +{
> + bpf_output_line_info (asm_out_file, insn);
> +}
> +
> +#undef TARGET_ASM_UNWIND_EMIT
> +#define TARGET_ASM_UNWIND_EMIT bpf_asm_out_unwind_emit
> +
> /* Output assembly directives to assemble data of various sized and
> alignments. */
>
> diff --git a/gcc/config/bpf/bpf.md b/gcc/config/bpf/bpf.md
> index 95859328d25..3fdf81b86a6 100644
> --- a/gcc/config/bpf/bpf.md
> +++ b/gcc/config/bpf/bpf.md
> @@ -546,7 +546,7 @@
> ;; operands[2] is next_arg_register
> ;; operands[3] is struct_value_size_rtx.
> ""
> - { return bpf_output_call (operands[0]); }
> + { return bpf_output_call ("call\t%0", operands, 0); }
> [(set_attr "type" "jmp")])
>
> (define_expand "call_value"
> @@ -569,7 +569,7 @@
> ;; operands[3] is next_arg_register
> ;; operands[4] is struct_value_size_rtx.
> ""
> - { return bpf_output_call (operands[1]); }
> + { return bpf_output_call ("call\t%1", operands, 1); }
> [(set_attr "type" "jmp")])
>
> (define_insn "sibcall"
> diff --git a/gcc/config/bpf/btfext-out.cc b/gcc/config/bpf/btfext-out.cc
> index ff1fd0739f1..42ec48e394e 100644
> --- a/gcc/config/bpf/btfext-out.cc
> +++ b/gcc/config/bpf/btfext-out.cc
> @@ -32,6 +32,7 @@
> #include "rtl.h"
> #include "tree-pretty-print.h"
> #include "cgraph.h"
> +#include "toplev.h" /* get_src_pwd */
>
> #include "btfext-out.h"
>
> @@ -124,7 +125,8 @@ struct GTY ((chain_next ("%h.next"))) btf_ext_funcinfo
> /* A lineinfo record, in the .BTF.ext lineinfo section. */
> struct GTY ((chain_next ("%h.next"))) btf_ext_lineinfo
> {
> - uint32_t insn_off; /* Offset of the instruction. */
> + const char *insn_label; /* Instruction label. */
> + const char *file_name; /* Source-code file name. */
> uint32_t file_name_off; /* Offset of file name in BTF string table. */
> uint32_t line_off; /* Offset of source line in BTF string table. */
> uint32_t line_col; /* Line number (bits 31-11) and column (11-0). */
> @@ -235,6 +237,26 @@ bpf_create_or_find_funcinfo (const char *fnname, const
> char *sec_name,
> return *head;
> }
>
> +/* Function to create a lineinfo node in info. */
> +
> +static struct btf_ext_lineinfo *
> +bpf_create_lineinfo (const char *sec_name, btf_ext_info_sec **in_sec = NULL)
> +{
> + struct btf_ext_info_sec *sec_elem =
> + btfext_info_sec_find_or_add (sec_name, true);
> +
> + if (in_sec != NULL)
> + *in_sec = sec_elem;
> +
> + struct btf_ext_lineinfo **head =
> + SEARCH_NODE_AND_RETURN(struct btf_ext_lineinfo,
> + sec_elem->line_info.head,
> + false);
> + *head = ggc_cleared_alloc<struct btf_ext_lineinfo> ();
> +
> + return *head;
> +}
> +
> /* Function to create a core_reloc node in info. */
>
> static struct btf_ext_core_reloc *
> @@ -429,6 +451,47 @@ btf_validate_funcinfo (btf_ext_info_sec *sec)
> }
> }
>
> +struct btf_ext_lineinfo *
> +btf_add_line_info_for (const char *label, const char *filename,
> + unsigned int line, unsigned int column)
> +{
> + const char *sec_name = decl_section_name (current_function_decl);
> +
> + if (sec_name == NULL)
> + sec_name = ".text";
> +
> + struct btf_ext_info_sec *sec = NULL;
> + struct btf_ext_lineinfo *info =
> + bpf_create_lineinfo (sec_name, &sec);
> +
> + unsigned int line_column = ((0x000fffff & line) << 12)
> + | (0x00000fff & column);
> +
> + info->insn_label = label;
> +
> + if (!IS_DIR_SEPARATOR (filename[0]))
> + {
> + char full_filename[256];
> +
> + /* Filename is a relative path. */
> + const char * cu_pwd = get_src_pwd ();
> + gcc_assert (strlen (cu_pwd) + strlen (filename) + 2 < 256);
> +
> + sprintf(full_filename, "%s%c%s", cu_pwd, DIR_SEPARATOR, filename);
> + info->file_name = ggc_strdup (full_filename);
> + }
> + else
> + /* Filename is an absolute path. */
> + info->file_name = ggc_strdup (filename);
> +
> + info->file_name_off = btf_ext_add_string (info->file_name);
> + info->line_off = 0;
> + info->line_col = line_column;
> +
> + sec->line_info.num_info += 1;
> + return info;
> +}
> +
> /* Compute the section size in section for func_info, line_info and core_info
> regions of .BTF.ext. */
>
> @@ -537,6 +600,48 @@ output_btfext_func_info (struct btf_ext_info_sec *sec)
> }
> }
>
> +/* Outputs line_info region on .BTF.ext. */
> +
> +static void
> +output_btfext_line_info (struct btf_ext_info_sec *sec)
> +{
> + unsigned int str_aux_off = ctfc_get_strtab_len (ctf_get_tu_ctfc (),
> + CTF_STRTAB);
> + bool executed = false;
> + while (sec != NULL)
> + {
> + uint32_t count = 0;
> + if (sec->line_info.num_info > 0)
> + {
> + if (executed == false && (executed = true))
> + dw2_asm_output_data (4, 16, "LineInfo entry size");
> + dw2_asm_output_data (4, sec->sec_name_off + str_aux_off,
> + "LineInfo section string for %s",
> + sec->sec_name);
> + dw2_asm_output_data (4, sec->line_info.num_info, "Number of entries");
> +
> + struct btf_ext_lineinfo *elem = sec->line_info.head;
> + while (elem != NULL)
> + {
> + count += 1;
> + dw2_asm_output_offset (4, elem->insn_label, NULL, "insn_label");
> +
> + unsigned int file_name_off = btf_ext_add_string (elem->file_name);
> + dw2_asm_output_data (4, file_name_off + str_aux_off,
> + "file_name_off");
> + dw2_asm_output_data (4, elem->line_off, "line_off");
> + dw2_asm_output_data (4, elem->line_col, "(line, col) (%u, %u)",
> + elem->line_col >> 12,
> + elem->line_col & 0x00000fff);
> + elem = elem->next;
> + }
> + }
> +
> + gcc_assert (count == sec->line_info.num_info);
> + sec = sec->next;
> + }
> +}
> +
> /* Output all CO-RE relocation sections. */
>
> static void
> @@ -609,6 +714,7 @@ btf_ext_output (void)
> {
> output_btfext_header ();
> output_btfext_func_info (btf_ext);
> + output_btfext_line_info (btf_ext);
> if (TARGET_BPF_CORE)
> output_btfext_core_sections ();
>
> diff --git a/gcc/config/bpf/btfext-out.h b/gcc/config/bpf/btfext-out.h
> index b36309475c9..9c6848324e7 100644
> --- a/gcc/config/bpf/btfext-out.h
> +++ b/gcc/config/bpf/btfext-out.h
> @@ -99,6 +99,10 @@ extern int bpf_core_get_sou_member_index
> (ctf_container_ref, const tree);
>
> struct btf_ext_funcinfo *btf_add_func_info_for (tree decl,
> const char *label);
> +struct btf_ext_lineinfo *
> +btf_add_line_info_for (const char *label, const char *filename,
> + unsigned int line, unsigned int column);
> +
> unsigned int btf_ext_add_string (const char *str);
>
> #ifdef __cplusplus
> diff --git a/gcc/testsuite/gcc.target/bpf/btfext-funcinfo.c
> b/gcc/testsuite/gcc.target/bpf/btfext-funcinfo.c
> index 6fdd14574ec..0f1e0ad1e89 100644
> --- a/gcc/testsuite/gcc.target/bpf/btfext-funcinfo.c
> +++ b/gcc/testsuite/gcc.target/bpf/btfext-funcinfo.c
> @@ -39,6 +39,5 @@ int bar_func (struct T *t)
> /* { dg-final { scan-assembler-times "ascii \"bar_sec.0\"\[\t
> \]+\[^\n\]*btf_aux_string" 1 } } */
> /* { dg-final { scan-assembler-times "FuncInfo entry size" 1 } } */
>
> -/* { dg-final { scan-assembler-times ".4byte\t0x1\t# Number of entries" 3 }
> } */
> -/* { dg-final { scan-assembler-times ".4byte\t0x2\t# Number of entries" 1 }
> } */
> +/* { dg-final { scan-assembler-times "FuncInfo
> section\[^\n\]*\n\[^0\]*0x1\t# Number of entries" 2 } } */
> /* { dg-final { scan-assembler-times "Required padding" 1 } } */
