| Message ID | 20240815173903.4172139-26-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Implement DWARF modversions | expand |
On 8/15/24 19:39, Sami Tolvanen wrote: > Start making gendwarfksyms more useful by adding support for > expanding DW_TAG_base_type types and basic DWARF attributes. > > Example: > > $ echo loops_per_jiffy | \ > scripts/gendwarfksyms/gendwarfksyms --debug vmlinux.o > ... > gendwarfksyms: process_exported_symbols: loops_per_jiffy > variable base_type unsigned long byte_size(8) encoding(7); > ... > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > --- > scripts/gendwarfksyms/dwarf.c | 121 +++++++++++++++++++++++++++++++++- > 1 file changed, 120 insertions(+), 1 deletion(-) > > diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c > index 956b30224316..a37c9049d18e 100644 > --- a/scripts/gendwarfksyms/dwarf.c > +++ b/scripts/gendwarfksyms/dwarf.c > @@ -5,6 +5,17 @@ > > #include "gendwarfksyms.h" > > +#define DEFINE_GET_ATTR(attr, type) \ > + static bool get_##attr##_attr(Dwarf_Die *die, unsigned int id, \ > + type *value) \ > + { \ > + Dwarf_Attribute da; \ > + return dwarf_attr(die, id, &da) && \ > + !dwarf_form##attr(&da, value); \ > + } > + > +DEFINE_GET_ATTR(udata, Dwarf_Word) > + > static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value) > { > Dwarf_Attribute da; > @@ -60,6 +71,74 @@ static int process(struct state *state, const char *s) > return 0; > } > > +#define MAX_FMT_BUFFER_SIZE 128 > + > +static int process_fmt(struct state *state, const char *fmt, ...) Nit: The state parameter is unused by a number of these process_*() functions, including the leaf process(). I suggest removing it so it doesn't need to be passed around unnecessarily. > +{ > + char buf[MAX_FMT_BUFFER_SIZE]; > + va_list args; > + int res; > + > + va_start(args, fmt); > + > + res = checkp(vsnprintf(buf, sizeof(buf), fmt, args)); > + if (res >= MAX_FMT_BUFFER_SIZE - 1) { This check looks off by one, though on the safe side: res >= sizeof(buf) > + error("vsnprintf overflow: increase MAX_FMT_BUFFER_SIZE"); > + res = -1; > + } else { > + res = check(process(state, buf)); > + } > + > + va_end(args); > + return res; > +} > + > +/* Process a fully qualified name from DWARF scopes */ > +static int process_fqn(struct state *state, Dwarf_Die *die) > +{ > + Dwarf_Die *scopes = NULL; > + const char *name; > + int res; > + int i; > + > + res = checkp(dwarf_getscopes_die(die, &scopes)); > + if (!res) { > + name = get_name(die); > + name = name ?: "<unnamed>"; > + return check(process(state, name)); > + } > + > + for (i = res - 1; i >= 0; i--) { > + if (dwarf_tag(&scopes[i]) == DW_TAG_compile_unit) > + continue; > + > + name = get_name(&scopes[i]); > + name = name ?: "<unnamed>"; > + check(process(state, name)); > + if (i > 0) > + check(process(state, "::")); Failed check(process()) calls here return immediately and so would leak scopes. However, I see this is fixed in the following patch "gendwarfksyms: Add a cache for processed DIEs" so it's ok. > + } > + > + free(scopes); > + return 0; > +} > + > +#define DEFINE_PROCESS_UDATA_ATTRIBUTE(attribute) \ > + static int process_##attribute##_attr(struct state *state, \ > + Dwarf_Die *die) \ > + { \ > + Dwarf_Word value; \ > + if (get_udata_attr(die, DW_AT_##attribute, &value)) \ > + check(process_fmt(state, \ > + " " #attribute "(%" PRIu64 ")", \ > + value)); \ > + return 0; \ > + } > + > +DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment) > +DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size) > +DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding) > + > bool match_all(Dwarf_Die *die) > { > return true; > @@ -81,6 +160,44 @@ int process_die_container(struct state *state, Dwarf_Die *die, > return 0; > } > > +static int process_type(struct state *state, Dwarf_Die *die); > + > +static int process_type_attr(struct state *state, Dwarf_Die *die) > +{ > + Dwarf_Die type; > + > + if (get_ref_die_attr(die, DW_AT_type, &type)) > + return check(process_type(state, &type)); > + > + /* Compilers can omit DW_AT_type -- print out 'void' to clarify */ > + return check(process(state, "base_type void")); > +} > + > +static int process_base_type(struct state *state, Dwarf_Die *die) > +{ > + check(process(state, "base_type ")); > + check(process_fqn(state, die)); > + check(process_byte_size_attr(state, die)); > + check(process_encoding_attr(state, die)); > + return check(process_alignment_attr(state, die)); > +} > + > +static int process_type(struct state *state, Dwarf_Die *die) > +{ > + int tag = dwarf_tag(die); > + > + switch (tag) { > + case DW_TAG_base_type: > + check(process_base_type(state, die)); > + break; > + default: > + debug("unimplemented type: %x", tag); > + break; > + } > + > + return 0; > +} > + > /* > * Exported symbol processing > */ > @@ -91,7 +208,9 @@ static int process_subprogram(struct state *state, Dwarf_Die *die) > > static int process_variable(struct state *state, Dwarf_Die *die) > { > - return check(process(state, "variable;\n")); > + check(process(state, "variable ")); > + check(process_type_attr(state, die)); > + return check(process(state, ";\n")); > } > > static int process_symbol_ptr(struct state *state, Dwarf_Die *die)
On Wed, Aug 28, 2024 at 02:46:03PM +0200, Petr Pavlu wrote: > > +static int process_fmt(struct state *state, const char *fmt, ...) > > Nit: The state parameter is unused by a number of these process_*() > functions, including the leaf process(). I suggest removing it so it > doesn't need to be passed around unnecessarily. Good point, I'll clean this up. > > + char buf[MAX_FMT_BUFFER_SIZE]; > > + va_list args; > > + int res; > > + > > + va_start(args, fmt); > > + > > + res = checkp(vsnprintf(buf, sizeof(buf), fmt, args)); > > + if (res >= MAX_FMT_BUFFER_SIZE - 1) { > > This check looks off by one, though on the safe side: > res >= sizeof(buf) True, I'll fix this too. > > + if (dwarf_tag(&scopes[i]) == DW_TAG_compile_unit) > > + continue; > > + > > + name = get_name(&scopes[i]); > > + name = name ?: "<unnamed>"; > > + check(process(state, name)); > > + if (i > 0) > > + check(process(state, "::")); > > Failed check(process()) calls here return immediately and so would leak > scopes. However, I see this is fixed in the following patch > "gendwarfksyms: Add a cache for processed DIEs" so it's ok. Yeah, I noticed this as well. I think Masahiro's suggestion to just exit immediately on errors cleans up this situation a bit. Sami
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c index 956b30224316..a37c9049d18e 100644 --- a/scripts/gendwarfksyms/dwarf.c +++ b/scripts/gendwarfksyms/dwarf.c @@ -5,6 +5,17 @@ #include "gendwarfksyms.h" +#define DEFINE_GET_ATTR(attr, type) \ + static bool get_##attr##_attr(Dwarf_Die *die, unsigned int id, \ + type *value) \ + { \ + Dwarf_Attribute da; \ + return dwarf_attr(die, id, &da) && \ + !dwarf_form##attr(&da, value); \ + } + +DEFINE_GET_ATTR(udata, Dwarf_Word) + static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value) { Dwarf_Attribute da; @@ -60,6 +71,74 @@ static int process(struct state *state, const char *s) return 0; } +#define MAX_FMT_BUFFER_SIZE 128 + +static int process_fmt(struct state *state, const char *fmt, ...) +{ + char buf[MAX_FMT_BUFFER_SIZE]; + va_list args; + int res; + + va_start(args, fmt); + + res = checkp(vsnprintf(buf, sizeof(buf), fmt, args)); + if (res >= MAX_FMT_BUFFER_SIZE - 1) { + error("vsnprintf overflow: increase MAX_FMT_BUFFER_SIZE"); + res = -1; + } else { + res = check(process(state, buf)); + } + + va_end(args); + return res; +} + +/* Process a fully qualified name from DWARF scopes */ +static int process_fqn(struct state *state, Dwarf_Die *die) +{ + Dwarf_Die *scopes = NULL; + const char *name; + int res; + int i; + + res = checkp(dwarf_getscopes_die(die, &scopes)); + if (!res) { + name = get_name(die); + name = name ?: "<unnamed>"; + return check(process(state, name)); + } + + for (i = res - 1; i >= 0; i--) { + if (dwarf_tag(&scopes[i]) == DW_TAG_compile_unit) + continue; + + name = get_name(&scopes[i]); + name = name ?: "<unnamed>"; + check(process(state, name)); + if (i > 0) + check(process(state, "::")); + } + + free(scopes); + return 0; +} + +#define DEFINE_PROCESS_UDATA_ATTRIBUTE(attribute) \ + static int process_##attribute##_attr(struct state *state, \ + Dwarf_Die *die) \ + { \ + Dwarf_Word value; \ + if (get_udata_attr(die, DW_AT_##attribute, &value)) \ + check(process_fmt(state, \ + " " #attribute "(%" PRIu64 ")", \ + value)); \ + return 0; \ + } + +DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment) +DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size) +DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding) + bool match_all(Dwarf_Die *die) { return true; @@ -81,6 +160,44 @@ int process_die_container(struct state *state, Dwarf_Die *die, return 0; } +static int process_type(struct state *state, Dwarf_Die *die); + +static int process_type_attr(struct state *state, Dwarf_Die *die) +{ + Dwarf_Die type; + + if (get_ref_die_attr(die, DW_AT_type, &type)) + return check(process_type(state, &type)); + + /* Compilers can omit DW_AT_type -- print out 'void' to clarify */ + return check(process(state, "base_type void")); +} + +static int process_base_type(struct state *state, Dwarf_Die *die) +{ + check(process(state, "base_type ")); + check(process_fqn(state, die)); + check(process_byte_size_attr(state, die)); + check(process_encoding_attr(state, die)); + return check(process_alignment_attr(state, die)); +} + +static int process_type(struct state *state, Dwarf_Die *die) +{ + int tag = dwarf_tag(die); + + switch (tag) { + case DW_TAG_base_type: + check(process_base_type(state, die)); + break; + default: + debug("unimplemented type: %x", tag); + break; + } + + return 0; +} + /* * Exported symbol processing */ @@ -91,7 +208,9 @@ static int process_subprogram(struct state *state, Dwarf_Die *die) static int process_variable(struct state *state, Dwarf_Die *die) { - return check(process(state, "variable;\n")); + check(process(state, "variable ")); + check(process_type_attr(state, die)); + return check(process(state, ";\n")); } static int process_symbol_ptr(struct state *state, Dwarf_Die *die)
Start making gendwarfksyms more useful by adding support for expanding DW_TAG_base_type types and basic DWARF attributes. Example: $ echo loops_per_jiffy | \ scripts/gendwarfksyms/gendwarfksyms --debug vmlinux.o ... gendwarfksyms: process_exported_symbols: loops_per_jiffy variable base_type unsigned long byte_size(8) encoding(7); ... Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- scripts/gendwarfksyms/dwarf.c | 121 +++++++++++++++++++++++++++++++++- 1 file changed, 120 insertions(+), 1 deletion(-)