On Fri, Sep 20, 2024 at 01:19:01AM -0700, Stephen Brennan wrote:
> Currently the "var" feature only encodes percpu variables. Add the
> ability to encode all global variables.
>
> This also drops the use of the symbol table to find variable names and
> compare them against DWARF names. We simply rely on the DWARF
> information to give us all the variables.
I applied the three first patches to the next branch that soon will move
to master, but the last patch I think does too many things and ends up
being too big.
For instance, you could have done the btf_encoder->skip_encoding_vars
transformation into a bitfield in a separate, prep patch, also you
mentions "this also drops the use of the symbol table", can this be made
a separate, prep patch?
There was a conflict with some new options I added (--padding,
--padding_ge) and I fixed that up and made the series available in the
btf_global_vars branch, can you please go from there and split the last
patch into smaller chunks?
Thanks for your work on this! I noticed that this is not the default,
i.e. one has to explicitely opt in to have the global variables encoded
in BTF, so that would be interesting to have spelled out in the chunked
out patch that introduces the feature, etc.
Also since we have it as a feature and can ask for global variables
using --btf_features=global_var, I don't think we need
--encode_btf_global_vars, right?
That will also make the patch smaller, and even if it was required, that
would be something to have in a separate patch.
- Arnaldo
> Signed-off-by: Stephen Brennan <stephen.s.brennan@xxxxxxxxxx>
> Tested-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> ---
> btf_encoder.c | 347 +++++++++++++++++++++------------------------
> btf_encoder.h | 8 ++
> dwarves.h | 1 +
> man-pages/pahole.1 | 8 +-
> pahole.c | 11 +-
> 5 files changed, 183 insertions(+), 192 deletions(-)
>
> diff --git a/btf_encoder.c b/btf_encoder.c
> index 97d35e0..d3a66a0 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -65,16 +65,13 @@ struct elf_function {
> struct btf_encoder_state state;
> };
>
> -struct var_info {
> - uint64_t addr;
> - const char *name;
> - uint32_t sz;
> -};
> -
> struct elf_secinfo {
> uint64_t addr;
> const char *name;
> uint64_t sz;
> + bool include;
> + uint32_t type;
> + struct gobuffer secinfo;
> };
>
> /*
> @@ -84,31 +81,24 @@ struct btf_encoder {
> struct list_head node;
> struct btf *btf;
> struct cu *cu;
> - struct gobuffer percpu_secinfo;
> const char *source_filename;
> const char *filename;
> struct elf_symtab *symtab;
> uint32_t type_id_off;
> bool has_index_type,
> need_index_type,
> - skip_encoding_vars,
> raw_output,
> verbose,
> force,
> gen_floats,
> skip_encoding_decl_tag,
> tag_kfuncs,
> - is_rel,
> gen_distilled_base;
> uint32_t array_index_id;
> struct elf_secinfo *secinfo;
> size_t seccnt;
> - struct {
> - struct var_info *vars;
> - int var_cnt;
> - int allocated;
> - uint32_t shndx;
> - } percpu;
> + int encode_vars;
> + uint32_t percpu_shndx;
> struct {
> struct elf_function *entries;
> int allocated;
> @@ -735,46 +725,56 @@ static int32_t btf_encoder__add_var(struct btf_encoder *encoder, uint32_t type,
> return id;
> }
>
> -static int32_t btf_encoder__add_var_secinfo(struct btf_encoder *encoder, uint32_t type,
> - uint32_t offset, uint32_t size)
> +static int32_t btf_encoder__add_var_secinfo(struct btf_encoder *encoder, int shndx,
> + uint32_t type, unsigned long addr, uint32_t size)
> {
> struct btf_var_secinfo si = {
> .type = type,
> - .offset = offset,
> + .offset = addr,
> .size = size,
> };
> - return gobuffer__add(&encoder->percpu_secinfo, &si, sizeof(si));
> + return gobuffer__add(&encoder->secinfo[shndx].secinfo, &si, sizeof(si));
> }
>
> int32_t btf_encoder__add_encoder(struct btf_encoder *encoder, struct btf_encoder *other)
> {
> - struct gobuffer *var_secinfo_buf = &other->percpu_secinfo;
> - size_t sz = gobuffer__size(var_secinfo_buf);
> - uint16_t nr_var_secinfo = sz / sizeof(struct btf_var_secinfo);
> - uint32_t type_id;
> - uint32_t next_type_id = btf__type_cnt(encoder->btf);
> - int32_t i, id;
> - struct btf_var_secinfo *vsi;
> -
> + int shndx;
> if (encoder == other)
> return 0;
>
> btf_encoder__add_saved_funcs(other);
>
> - for (i = 0; i < nr_var_secinfo; i++) {
> - vsi = (struct btf_var_secinfo *)var_secinfo_buf->entries + i;
> - type_id = next_type_id + vsi->type - 1; /* Type ID starts from 1 */
> - id = btf_encoder__add_var_secinfo(encoder, type_id, vsi->offset, vsi->size);
> - if (id < 0)
> - return id;
> + for (shndx = 0; shndx < other->seccnt; shndx++) {
> + struct gobuffer *var_secinfo_buf = &other->secinfo[shndx].secinfo;
> + size_t sz = gobuffer__size(var_secinfo_buf);
> + uint16_t nr_var_secinfo = sz / sizeof(struct btf_var_secinfo);
> + uint32_t type_id;
> + uint32_t next_type_id = btf__type_cnt(encoder->btf);
> + int32_t i, id;
> + struct btf_var_secinfo *vsi;
> +
> + if (strcmp(encoder->secinfo[shndx].name, other->secinfo[shndx].name)) {
> + fprintf(stderr, "mismatched ELF sections at index %d: \"%s\", \"%s\"\n",
> + shndx, encoder->secinfo[shndx].name, other->secinfo[shndx].name);
> + return -1;
> + }
> +
> + for (i = 0; i < nr_var_secinfo; i++) {
> + vsi = (struct btf_var_secinfo *)var_secinfo_buf->entries + i;
> + type_id = next_type_id + vsi->type - 1; /* Type ID starts from 1 */
> + id = btf_encoder__add_var_secinfo(encoder, shndx, type_id, vsi->offset, vsi->size);
> + if (id < 0)
> + return id;
> + }
> }
>
> return btf__add_btf(encoder->btf, other->btf);
> }
>
> -static int32_t btf_encoder__add_datasec(struct btf_encoder *encoder, const char *section_name)
> +static int32_t btf_encoder__add_datasec(struct btf_encoder *encoder, int shndx)
> {
> - struct gobuffer *var_secinfo_buf = &encoder->percpu_secinfo;
> + struct gobuffer *var_secinfo_buf = &encoder->secinfo[shndx].secinfo;
> + const char *section_name = encoder->secinfo[shndx].name;
> struct btf *btf = encoder->btf;
> size_t sz = gobuffer__size(var_secinfo_buf);
> uint16_t nr_var_secinfo = sz / sizeof(struct btf_var_secinfo);
> @@ -1741,13 +1741,14 @@ out:
> int btf_encoder__encode(struct btf_encoder *encoder)
> {
> bool should_tag_kfuncs;
> - int err;
> + int err, shndx;
>
> /* for single-threaded case, saved funcs are added here */
> btf_encoder__add_saved_funcs(encoder);
>
> - if (gobuffer__size(&encoder->percpu_secinfo) != 0)
> - btf_encoder__add_datasec(encoder, PERCPU_SECTION);
> + for (shndx = 0; shndx < encoder->seccnt; shndx++)
> + if (gobuffer__size(&encoder->secinfo[shndx].secinfo))
> + btf_encoder__add_datasec(encoder, shndx);
>
> /* Empty file, nothing to do, so... done! */
> if (btf__type_cnt(encoder->btf) == 1)
> @@ -1797,111 +1798,18 @@ int btf_encoder__encode(struct btf_encoder *encoder)
> return err;
> }
>
> -static int percpu_var_cmp(const void *_a, const void *_b)
> -{
> - const struct var_info *a = _a;
> - const struct var_info *b = _b;
> -
> - if (a->addr == b->addr)
> - return 0;
> - return a->addr < b->addr ? -1 : 1;
> -}
> -
> -static bool btf_encoder__percpu_var_exists(struct btf_encoder *encoder, uint64_t addr, uint32_t *sz, const char **name)
> -{
> - struct var_info key = { .addr = addr };
> - const struct var_info *p = bsearch(&key, encoder->percpu.vars, encoder->percpu.var_cnt,
> - sizeof(encoder->percpu.vars[0]), percpu_var_cmp);
> - if (!p)
> - return false;
> -
> - *sz = p->sz;
> - *name = p->name;
> - return true;
> -}
> -
> -static int btf_encoder__collect_percpu_var(struct btf_encoder *encoder, GElf_Sym *sym, size_t sym_sec_idx)
> -{
> - const char *sym_name;
> - uint64_t addr;
> - uint32_t size;
> -
> - /* compare a symbol's shndx to determine if it's a percpu variable */
> - if (sym_sec_idx != encoder->percpu.shndx)
> - return 0;
> - if (elf_sym__type(sym) != STT_OBJECT)
> - return 0;
> -
> - addr = elf_sym__value(sym);
> -
> - size = elf_sym__size(sym);
> - if (!size)
> - return 0; /* ignore zero-sized symbols */
> -
> - sym_name = elf_sym__name(sym, encoder->symtab);
> - if (!btf_name_valid(sym_name)) {
> - dump_invalid_symbol("Found symbol of invalid name when encoding btf",
> - sym_name, encoder->verbose, encoder->force);
> - if (encoder->force)
> - return 0;
> - return -1;
> - }
> -
> - if (encoder->verbose)
> - printf("Found per-CPU symbol '%s' at address 0x%" PRIx64 "\n", sym_name, addr);
> -
> - /* Make sure addr is section-relative. For kernel modules (which are
> - * ET_REL files) this is already the case. For vmlinux (which is an
> - * ET_EXEC file) we need to subtract the section address.
> - */
> - if (!encoder->is_rel)
> - addr -= encoder->secinfo[encoder->percpu.shndx].addr;
> -
> - if (encoder->percpu.var_cnt == encoder->percpu.allocated) {
> - struct var_info *new;
> -
> - new = reallocarray_grow(encoder->percpu.vars,
> - &encoder->percpu.allocated,
> - sizeof(*encoder->percpu.vars));
> - if (!new) {
> - fprintf(stderr, "Failed to allocate memory for variables\n");
> - return -1;
> - }
> - encoder->percpu.vars = new;
> - }
> - encoder->percpu.vars[encoder->percpu.var_cnt].addr = addr;
> - encoder->percpu.vars[encoder->percpu.var_cnt].sz = size;
> - encoder->percpu.vars[encoder->percpu.var_cnt].name = sym_name;
> - encoder->percpu.var_cnt++;
> -
> - return 0;
> -}
>
> -static int btf_encoder__collect_symbols(struct btf_encoder *encoder, bool collect_percpu_vars)
> +static int btf_encoder__collect_symbols(struct btf_encoder *encoder)
> {
> - Elf32_Word sym_sec_idx;
> + uint32_t sym_sec_idx;
> uint32_t core_id;
> GElf_Sym sym;
>
> - /* cache variables' addresses, preparing for searching in symtab. */
> - encoder->percpu.var_cnt = 0;
> -
> - /* search within symtab for percpu variables */
> elf_symtab__for_each_symbol_index(encoder->symtab, core_id, sym, sym_sec_idx) {
> - if (collect_percpu_vars && btf_encoder__collect_percpu_var(encoder, &sym, sym_sec_idx))
> - return -1;
> if (btf_encoder__collect_function(encoder, &sym))
> return -1;
> }
>
> - if (collect_percpu_vars) {
> - if (encoder->percpu.var_cnt)
> - qsort(encoder->percpu.vars, encoder->percpu.var_cnt, sizeof(encoder->percpu.vars[0]), percpu_var_cmp);
> -
> - if (encoder->verbose)
> - printf("Found %d per-CPU variables!\n", encoder->percpu.var_cnt);
> - }
> -
> if (encoder->functions.cnt) {
> qsort(encoder->functions.entries, encoder->functions.cnt, sizeof(encoder->functions.entries[0]),
> functions_cmp);
> @@ -1923,75 +1831,128 @@ static bool ftype__has_arg_names(const struct ftype *ftype)
> return true;
> }
>
> +static int get_elf_section(struct btf_encoder *encoder, unsigned long addr)
> +{
> + /* Start at index 1 to ignore initial SHT_NULL section */
> + for (int i = 1; i < encoder->seccnt; i++)
> + /* Variables are only present in PROGBITS or NOBITS (.bss) */
> + if ((encoder->secinfo[i].type == SHT_PROGBITS ||
> + encoder->secinfo[i].type == SHT_NOBITS) &&
> + encoder->secinfo[i].addr <= addr &&
> + (addr - encoder->secinfo[i].addr) < encoder->secinfo[i].sz)
> + return i;
> + return -ENOENT;
> +}
> +
> +/*
> + * Filter out variables / symbol names with common prefixes and no useful
> + * values. Prefixes should be added sparingly, and it should be objectively
> + * obvious that they are not useful.
> + */
> +static bool filter_variable_name(const char *name)
> +{
> + static const struct { char *s; size_t len; } skip[] = {
> + #define X(str) {str, sizeof(str) - 1}
> + X("__UNIQUE_ID"),
> + X("__tpstrtab_"),
> + X("__exitcall_"),
> + X("__func_stack_frame_non_standard_")
> + #undef X
> + };
> + int i;
> +
> + if (*name != '_')
> + return false;
> +
> + for (i = 0; i < ARRAY_SIZE(skip); i++) {
> + if (strncmp(name, skip[i].s, skip[i].len) == 0)
> + return true;
> + }
> + return false;
> +}
> +
> static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder)
> {
> struct cu *cu = encoder->cu;
> uint32_t core_id;
> struct tag *pos;
> int err = -1;
> - struct elf_secinfo *pcpu_scn = &encoder->secinfo[encoder->percpu.shndx];
>
> - if (encoder->percpu.shndx == 0 || !encoder->symtab)
> + if (!encoder->symtab)
> return 0;
>
> if (encoder->verbose)
> - printf("search cu '%s' for percpu global variables.\n", cu->name);
> + printf("search cu '%s' for global variables.\n", cu->name);
>
> cu__for_each_variable(cu, core_id, pos) {
> struct variable *var = tag__variable(pos);
> - uint32_t size, type, linkage;
> - const char *name, *dwarf_name;
> + uint32_t type, linkage;
> + const char *name;
> struct llvm_annotation *annot;
> const struct tag *tag;
> + int shndx;
> + struct elf_secinfo *sec = NULL;
> uint64_t addr;
> int id;
> + unsigned long size;
>
> + /* Skip incomplete (non-defining) declarations */
> if (var->declaration && !var->spec)
> continue;
>
> - /* percpu variables are allocated in global space */
> - if (variable__scope(var) != VSCOPE_GLOBAL && !var->spec)
> + /*
> + * top_level: indicates that the variable is declared at the top
> + * level of the CU, and thus it is globally scoped.
> + * artificial: indicates that the variable is a compiler-generated
> + * "fake" variable that doesn't appear in the source.
> + * scope: set by pahole to indicate the type of storage the
> + * variable has. GLOBAL indicates it is stored in static
> + * memory (as opposed to a stack variable or register)
> + *
> + * Some variables are "top_level" but not GLOBAL:
> + * e.g. current_stack_pointer, which is a register variable,
> + * despite having global CU-declarations. We don't want that,
> + * since no code could actually find this variable.
> + * Some variables are GLOBAL but not top_level:
> + * e.g. function static variables
> + */
> + if (!var->top_level || var->artificial || var->scope != VSCOPE_GLOBAL)
> continue;
>
> /* addr has to be recorded before we follow spec */
> addr = var->ip.addr;
> - dwarf_name = variable__name(var);
>
> - /* Make sure addr is section-relative. DWARF, unlike ELF,
> - * always contains virtual symbol addresses, so subtract
> - * the section address unconditionally.
> - */
> - if (addr < pcpu_scn->addr || addr >= pcpu_scn->addr + pcpu_scn->sz)
> + /* Get the ELF section info for the variable */
> + shndx = get_elf_section(encoder, addr);
> + if (shndx >= 0 && shndx < encoder->seccnt)
> + sec = &encoder->secinfo[shndx];
> + if (!sec || !sec->include)
> continue;
> - addr -= pcpu_scn->addr;
>
> - if (!btf_encoder__percpu_var_exists(encoder, addr, &size, &name))
> - continue; /* not a per-CPU variable */
> + /* Convert addr to section relative */
> + addr -= sec->addr;
>
> - /* A lot of "special" DWARF variables (e.g, __UNIQUE_ID___xxx)
> - * have addr == 0, which is the same as, say, valid
> - * fixed_percpu_data per-CPU variable. To distinguish between
> - * them, additionally compare DWARF and ELF symbol names. If
> - * DWARF doesn't provide proper name, pessimistically assume
> - * bad variable.
> - *
> - * Examples of such special variables are:
> - *
> - * 1. __ADDRESSABLE(sym), which are forcely emitted as symbols.
> - * 2. __UNIQUE_ID(prefix), which are introduced to generate unique ids.
> - * 3. __exitcall(fn), functions which are labeled as exit calls.
> - *
> - * This is relevant only for vmlinux image, as for kernel
> - * modules per-CPU data section has non-zero offset so all
> - * per-CPU symbols have non-zero values.
> - */
> - if (var->ip.addr == 0) {
> - if (!dwarf_name || strcmp(dwarf_name, name))
> + /* DWARF specification reference should be followed, because
> + * information like the name & type may not be present on var */
> + if (var->spec)
> + var = var->spec;
> +
> + name = variable__name(var);
> + if (!name)
> + continue;
> +
> + /* Check for invalid BTF names */
> + if (!btf_name_valid(name)) {
> + dump_invalid_symbol("Found invalid variable name when encoding btf",
> + name, encoder->verbose, encoder->force);
> + if (encoder->force)
> continue;
> + else
> + return -1;
> }
>
> - if (var->spec)
> - var = var->spec;
> + if (filter_variable_name(name))
> + continue;
>
> if (var->ip.tag.type == 0) {
> fprintf(stderr, "error: found variable '%s' in CU '%s' that has void type\n",
> @@ -2003,9 +1964,10 @@ static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder)
> }
>
> tag = cu__type(cu, var->ip.tag.type);
> - if (tag__size(tag, cu) == 0) {
> + size = tag__size(tag, cu);
> + if (size == 0) {
> if (encoder->verbose)
> - fprintf(stderr, "Ignoring zero-sized per-CPU variable '%s'...\n", dwarf_name ?: "<missing name>");
> + fprintf(stderr, "Ignoring zero-sized variable '%s'...\n", name ?: "<missing name>");
> continue;
> }
>
> @@ -2035,13 +1997,14 @@ static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder)
> }
>
> /*
> - * add a BTF_VAR_SECINFO in encoder->percpu_secinfo, which will be added into
> - * encoder->types later when we add BTF_VAR_DATASEC.
> + * Add the variable to the secinfo for the section it appears in.
> + * Later we will generate a BTF_VAR_DATASEC for all any section with
> + * an encoded variable.
> */
> - id = btf_encoder__add_var_secinfo(encoder, id, addr, size);
> + id = btf_encoder__add_var_secinfo(encoder, shndx, id, addr, size);
> if (id < 0) {
> fprintf(stderr, "error: failed to encode section info for variable '%s' at addr 0x%" PRIx64 "\n",
> - name, addr);
> + name, addr);
> goto out;
> }
> }
> @@ -2068,7 +2031,6 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
>
> encoder->force = conf_load->btf_encode_force;
> encoder->gen_floats = conf_load->btf_gen_floats;
> - encoder->skip_encoding_vars = conf_load->skip_encoding_btf_vars;
> encoder->skip_encoding_decl_tag = conf_load->skip_encoding_btf_decl_tag;
> encoder->tag_kfuncs = conf_load->btf_decl_tag_kfuncs;
> encoder->gen_distilled_base = conf_load->btf_gen_distilled_base;
> @@ -2076,6 +2038,11 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
> encoder->has_index_type = false;
> encoder->need_index_type = false;
> encoder->array_index_id = 0;
> + encoder->encode_vars = 0;
> + if (!conf_load->skip_encoding_btf_vars)
> + encoder->encode_vars |= BTF_VAR_PERCPU;
> + if (conf_load->encode_btf_global_vars)
> + encoder->encode_vars |= BTF_VAR_GLOBAL;
>
> GElf_Ehdr ehdr;
>
> @@ -2085,8 +2052,6 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
> goto out_delete;
> }
>
> - encoder->is_rel = ehdr.e_type == ET_REL;
> -
> switch (ehdr.e_ident[EI_DATA]) {
> case ELFDATA2LSB:
> btf__set_endianness(encoder->btf, BTF_LITTLE_ENDIAN);
> @@ -2127,15 +2092,21 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
> encoder->secinfo[shndx].addr = shdr.sh_addr;
> encoder->secinfo[shndx].sz = shdr.sh_size;
> encoder->secinfo[shndx].name = secname;
> -
> - if (strcmp(secname, PERCPU_SECTION) == 0)
> - encoder->percpu.shndx = shndx;
> + encoder->secinfo[shndx].type = shdr.sh_type;
> + if (encoder->encode_vars & BTF_VAR_GLOBAL)
> + encoder->secinfo[shndx].include = true;
> +
> + if (strcmp(secname, PERCPU_SECTION) == 0) {
> + encoder->percpu_shndx = shndx;
> + if (encoder->encode_vars & BTF_VAR_PERCPU)
> + encoder->secinfo[shndx].include = true;
> + }
> }
>
> - if (!encoder->percpu.shndx && encoder->verbose)
> + if (!encoder->percpu_shndx && encoder->verbose)
> printf("%s: '%s' doesn't have '%s' section\n", __func__, cu->filename, PERCPU_SECTION);
>
> - if (btf_encoder__collect_symbols(encoder, !encoder->skip_encoding_vars))
> + if (btf_encoder__collect_symbols(encoder))
> goto out_delete;
>
> if (encoder->verbose)
> @@ -2156,7 +2127,8 @@ void btf_encoder__delete(struct btf_encoder *encoder)
> return;
>
> btf_encoders__delete(encoder);
> - __gobuffer__delete(&encoder->percpu_secinfo);
> + for (int i = 0; i < encoder->seccnt; i++)
> + __gobuffer__delete(&encoder->secinfo[i].secinfo);
> zfree(&encoder->filename);
> zfree(&encoder->source_filename);
> btf__free(encoder->btf);
> @@ -2166,9 +2138,6 @@ void btf_encoder__delete(struct btf_encoder *encoder)
> encoder->functions.allocated = encoder->functions.cnt = 0;
> free(encoder->functions.entries);
> encoder->functions.entries = NULL;
> - encoder->percpu.allocated = encoder->percpu.var_cnt = 0;
> - free(encoder->percpu.vars);
> - encoder->percpu.vars = NULL;
>
> free(encoder);
> }
> @@ -2321,7 +2290,7 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu, struct co
> goto out;
> }
>
> - if (!encoder->skip_encoding_vars)
> + if (encoder->encode_vars)
> err = btf_encoder__encode_cu_variables(encoder);
>
> /* It is only safe to delete this CU if we have not stashed any static
> diff --git a/btf_encoder.h b/btf_encoder.h
> index f54c95a..5e4d53a 100644
> --- a/btf_encoder.h
> +++ b/btf_encoder.h
> @@ -16,7 +16,15 @@ struct btf;
> struct cu;
> struct list_head;
>
> +/* Bit flags specifying which kinds of variables are emitted */
> +enum btf_var_option {
> + BTF_VAR_NONE = 0,
> + BTF_VAR_PERCPU = 1,
> + BTF_VAR_GLOBAL = 2,
> +};
> +
> struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filename, struct btf *base_btf, bool verbose, struct conf_load *conf_load);
> +
> void btf_encoder__delete(struct btf_encoder *encoder);
>
> int btf_encoder__encode(struct btf_encoder *encoder);
> diff --git a/dwarves.h b/dwarves.h
> index 0fede91..fef881f 100644
> --- a/dwarves.h
> +++ b/dwarves.h
> @@ -92,6 +92,7 @@ struct conf_load {
> bool btf_gen_optimized;
> bool skip_encoding_btf_inconsistent_proto;
> bool skip_encoding_btf_vars;
> + bool encode_btf_global_vars;
> bool btf_gen_floats;
> bool btf_encode_force;
> bool reproducible_build;
> diff --git a/man-pages/pahole.1 b/man-pages/pahole.1
> index 0a9d8ac..4bc2d03 100644
> --- a/man-pages/pahole.1
> +++ b/man-pages/pahole.1
> @@ -230,7 +230,10 @@ the debugging information.
>
> .TP
> .B \-\-skip_encoding_btf_vars
> -Do not encode VARs in BTF.
> +.TQ
> +.B \-\-encode_btf_global_vars
> +By default, VARs are encoded only for percpu variables. These options allow
> +to skip encoding them, or alternatively to encode all global variables too.
>
> .TP
> .B \-\-skip_encoding_btf_decl_tag
> @@ -296,7 +299,8 @@ Encode BTF using the specified feature list, or specify 'default' for all standa
> encode_force Ignore invalid symbols when encoding BTF; for example
> if a symbol has an invalid name, it will be ignored
> and BTF encoding will continue.
> - var Encode variables using BTF_KIND_VAR in BTF.
> + var Encode percpu variables using BTF_KIND_VAR in BTF.
> + global_var Encode all global variables in the same way.
> float Encode floating-point types in BTF.
> decl_tag Encode declaration tags using BTF_KIND_DECL_TAG.
> type_tag Encode type tags using BTF_KIND_TYPE_TAG.
> diff --git a/pahole.c b/pahole.c
> index a33490d..b123be1 100644
> --- a/pahole.c
> +++ b/pahole.c
> @@ -1239,6 +1239,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
> #define ARGP_contains_enumerator 344
> #define ARGP_reproducible_build 345
> #define ARGP_running_kernel_vmlinux 346
> +#define ARGP_encode_btf_global_vars 347
>
> /* --btf_features=feature1[,feature2,..] allows us to specify
> * a list of requested BTF features or "default" to enable all default
> @@ -1285,6 +1286,7 @@ struct btf_feature {
> } btf_features[] = {
> BTF_DEFAULT_FEATURE(encode_force, btf_encode_force, false),
> BTF_DEFAULT_FEATURE(var, skip_encoding_btf_vars, true),
> + BTF_DEFAULT_FEATURE(global_var, encode_btf_global_vars, false),
> BTF_DEFAULT_FEATURE(float, btf_gen_floats, false),
> BTF_DEFAULT_FEATURE(decl_tag, skip_encoding_btf_decl_tag, true),
> BTF_DEFAULT_FEATURE(type_tag, skip_encoding_btf_type_tag, true),
> @@ -1720,7 +1722,12 @@ static const struct argp_option pahole__options[] = {
> {
> .name = "skip_encoding_btf_vars",
> .key = ARGP_skip_encoding_btf_vars,
> - .doc = "Do not encode VARs in BTF."
> + .doc = "Do not encode any VARs in BTF [if this is not specified, only percpu variables are encoded. To encode global variables too, use --encode_btf_global_vars]."
> + },
> + {
> + .name = "encode_btf_global_vars",
> + .key = ARGP_skip_encoding_btf_vars,
> + .doc = "Encode all global VARs in BTF [if this is not specified, only percpu variables are encoded]."
> },
> {
> .name = "btf_encode_force",
> @@ -2047,6 +2054,8 @@ static error_t pahole__options_parser(int key, char *arg,
> show_supported_btf_features(stdout); exit(0);
> case ARGP_btf_features_strict:
> parse_btf_features(arg, true); break;
> + case ARGP_encode_btf_global_vars:
> + conf_load.encode_btf_global_vars = true; break;
> default:
> return ARGP_ERR_UNKNOWN;
> }
> --
> 2.43.5
