diff mbox series

[v6,bpf-next,02/11] bpftool: Dump the kernel symbol's module name

Message ID 20230628115329.248450-3-laoar.shao@gmail.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf: Support ->fill_link_info for kprobe_multi and perf_event links | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 8 this patch: 8
netdev/cc_maintainers success CCed 13 of 13 maintainers
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch warning WARNING: line length of 92 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-PR success PR summary
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Commit Message

Yafang Shao June 28, 2023, 11:53 a.m. UTC 
If the kernel symbol is in a module, we will dump the module name as
well. The square brackets around the module name are trimmed.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
---
 tools/bpf/bpftool/xlated_dumper.c | 6 +++++-
 tools/bpf/bpftool/xlated_dumper.h | 2 ++
 2 files changed, 7 insertions(+), 1 deletion(-)

Comments

Quentin Monnet June 29, 2023, 1:46 p.m. UTC | #1 
2023-06-28 11:53 UTC+0000 ~ Yafang Shao <laoar.shao@gmail.com>
> If the kernel symbol is in a module, we will dump the module name as
> well. The square brackets around the module name are trimmed.
> 
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> Reviewed-by: Quentin Monnet <quentin@isovalent.com>
> ---
>  tools/bpf/bpftool/xlated_dumper.c | 6 +++++-
>  tools/bpf/bpftool/xlated_dumper.h | 2 ++
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
> index da608e10c843..567f56dfd9f1 100644
> --- a/tools/bpf/bpftool/xlated_dumper.c
> +++ b/tools/bpf/bpftool/xlated_dumper.c
> @@ -46,7 +46,11 @@ void kernel_syms_load(struct dump_data *dd)
>  		}
>  		dd->sym_mapping = tmp;
>  		sym = &dd->sym_mapping[dd->sym_count];
> -		if (sscanf(buff, "%p %*c %s", &address, sym->name) != 2)
> +
> +		/* module is optional */
> +		sym->module[0] = '\0';
> +		/* trim the square brackets around the module name */
> +		if (sscanf(buff, "%p %*c %s [%[^]]s", &address, sym->name, sym->module) < 2)

Looking again at this patch, we should be good for parsing the module
name with the sscanf() because I don't expect a module name longer than
MODULE_MAX_NAME to show up, but I wonder what guarantee we have about
symbols names staying under SYM_MAX_NAME? Maybe we should specify the
max length to read, to remain on the safe side (or in case these limits
change in the future). But it doesn't have to be part of your set, I can
send a follow-up after that.

>  			continue;
>  		sym->address = (unsigned long)address;
>  		if (!strcmp(sym->name, "__bpf_call_base")) {
> diff --git a/tools/bpf/bpftool/xlated_dumper.h b/tools/bpf/bpftool/xlated_dumper.h
> index 9a946377b0e6..db3ba0671501 100644
> --- a/tools/bpf/bpftool/xlated_dumper.h
> +++ b/tools/bpf/bpftool/xlated_dumper.h
> @@ -5,12 +5,14 @@
>  #define __BPF_TOOL_XLATED_DUMPER_H
>  
>  #define SYM_MAX_NAME	256
> +#define MODULE_MAX_NAME	64
>  
>  struct bpf_prog_linfo;
>  
>  struct kernel_sym {
>  	unsigned long address;
>  	char name[SYM_MAX_NAME];
> +	char module[MODULE_MAX_NAME];
>  };
>  
>  struct dump_data {
Yafang Shao June 30, 2023, 2:22 a.m. UTC | #2 
On Thu, Jun 29, 2023 at 9:46 PM Quentin Monnet <quentin@isovalent.com> wrote:
>
> 2023-06-28 11:53 UTC+0000 ~ Yafang Shao <laoar.shao@gmail.com>
> > If the kernel symbol is in a module, we will dump the module name as
> > well. The square brackets around the module name are trimmed.
> >
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > Reviewed-by: Quentin Monnet <quentin@isovalent.com>
> > ---
> >  tools/bpf/bpftool/xlated_dumper.c | 6 +++++-
> >  tools/bpf/bpftool/xlated_dumper.h | 2 ++
> >  2 files changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
> > index da608e10c843..567f56dfd9f1 100644
> > --- a/tools/bpf/bpftool/xlated_dumper.c
> > +++ b/tools/bpf/bpftool/xlated_dumper.c
> > @@ -46,7 +46,11 @@ void kernel_syms_load(struct dump_data *dd)
> >               }
> >               dd->sym_mapping = tmp;
> >               sym = &dd->sym_mapping[dd->sym_count];
> > -             if (sscanf(buff, "%p %*c %s", &address, sym->name) != 2)
> > +
> > +             /* module is optional */
> > +             sym->module[0] = '\0';
> > +             /* trim the square brackets around the module name */
> > +             if (sscanf(buff, "%p %*c %s [%[^]]s", &address, sym->name, sym->module) < 2)
>
> Looking again at this patch, we should be good for parsing the module
> name with the sscanf() because I don't expect a module name longer than
> MODULE_MAX_NAME to show up, but I wonder what guarantee we have about
> symbols names staying under SYM_MAX_NAME? Maybe we should specify the
> max length to read, to remain on the safe side (or in case these limits
> change in the future). But it doesn't have to be part of your set, I can
> send a follow-up after that.

Great, thanks for your work!
diff mbox series

Patch

diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
index da608e10c843..567f56dfd9f1 100644
--- a/tools/bpf/bpftool/xlated_dumper.c
+++ b/tools/bpf/bpftool/xlated_dumper.c
@@ -46,7 +46,11 @@  void kernel_syms_load(struct dump_data *dd)
 		}
 		dd->sym_mapping = tmp;
 		sym = &dd->sym_mapping[dd->sym_count];
-		if (sscanf(buff, "%p %*c %s", &address, sym->name) != 2)
+
+		/* module is optional */
+		sym->module[0] = '\0';
+		/* trim the square brackets around the module name */
+		if (sscanf(buff, "%p %*c %s [%[^]]s", &address, sym->name, sym->module) < 2)
 			continue;
 		sym->address = (unsigned long)address;
 		if (!strcmp(sym->name, "__bpf_call_base")) {
diff --git a/tools/bpf/bpftool/xlated_dumper.h b/tools/bpf/bpftool/xlated_dumper.h
index 9a946377b0e6..db3ba0671501 100644
--- a/tools/bpf/bpftool/xlated_dumper.h
+++ b/tools/bpf/bpftool/xlated_dumper.h
@@ -5,12 +5,14 @@ 
 #define __BPF_TOOL_XLATED_DUMPER_H
 
 #define SYM_MAX_NAME	256
+#define MODULE_MAX_NAME	64
 
 struct bpf_prog_linfo;
 
 struct kernel_sym {
 	unsigned long address;
 	char name[SYM_MAX_NAME];
+	char module[MODULE_MAX_NAME];
 };
 
 struct dump_data {