diff mbox series

[v3,bpf-next,11/11] bpftool: support displaying relocated-with-base split BTF

Message ID 20240510103052.850012-12-alan.maguire@oracle.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf: support resilient split BTF | expand

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Commit Message

Alan Maguire May 10, 2024, 10:30 a.m. UTC 
If the -R <base_btf> option is used, we can display BTF that has been
generated with distilled base BTF in its relocated form.  For example
for bpf_testmod.ko (which is built as an out-of-tree module, so has
a distilled .BTF.base section:

bpftool btf dump file bpf_testmod.ko

Alternatively, we can display content relocated with
(a possibly changed) base BTF via

bpftool btf dump -R /sys/kernel/btf/vmlinux bpf_testmod.ko

The latter mirrors how the kernel will handle such split
BTF; it relocates its representation with the running
kernel, and if successful, renumbers BTF ids to reference
the current vmlinux BTF.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 tools/bpf/bpftool/Documentation/bpftool-btf.rst | 15 ++++++++++++++-
 tools/bpf/bpftool/bash-completion/bpftool       |  7 ++++---
 tools/bpf/bpftool/btf.c                         | 11 ++++++++++-
 tools/bpf/bpftool/main.c                        | 14 +++++++++++++-
 tools/bpf/bpftool/main.h                        |  2 ++
 5 files changed, 43 insertions(+), 6 deletions(-)

Comments

Eduard Zingerman May 11, 2024, 9:32 a.m. UTC | #1 
On Fri, 2024-05-10 at 11:30 +0100, Alan Maguire wrote:
> If the -R <base_btf> option is used, we can display BTF that has been
> generated with distilled base BTF in its relocated form.  For example
> for bpf_testmod.ko (which is built as an out-of-tree module, so has
> a distilled .BTF.base section:
> 
> bpftool btf dump file bpf_testmod.ko
> 
> Alternatively, we can display content relocated with
> (a possibly changed) base BTF via
> 
> bpftool btf dump -R /sys/kernel/btf/vmlinux bpf_testmod.ko
> 
> The latter mirrors how the kernel will handle such split
> BTF; it relocates its representation with the running
> kernel, and if successful, renumbers BTF ids to reference
> the current vmlinux BTF.
> 
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Quentin Monnet May 13, 2024, 11:12 a.m. UTC | #2 
2024-05-10 11:32 UTC+0100 ~ Alan Maguire <alan.maguire@oracle.com>
> If the -R <base_btf> option is used, we can display BTF that has been
> generated with distilled base BTF in its relocated form.  For example
> for bpf_testmod.ko (which is built as an out-of-tree module, so has
> a distilled .BTF.base section:
> 
> bpftool btf dump file bpf_testmod.ko
> 
> Alternatively, we can display content relocated with
> (a possibly changed) base BTF via
> 
> bpftool btf dump -R /sys/kernel/btf/vmlinux bpf_testmod.ko
> 
> The latter mirrors how the kernel will handle such split
> BTF; it relocates its representation with the running
> kernel, and if successful, renumbers BTF ids to reference
> the current vmlinux BTF.
> 
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> ---
>  tools/bpf/bpftool/Documentation/bpftool-btf.rst | 15 ++++++++++++++-
>  tools/bpf/bpftool/bash-completion/bpftool       |  7 ++++---
>  tools/bpf/bpftool/btf.c                         | 11 ++++++++++-
>  tools/bpf/bpftool/main.c                        | 14 +++++++++++++-
>  tools/bpf/bpftool/main.h                        |  2 ++
>  5 files changed, 43 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/bpf/bpftool/Documentation/bpftool-btf.rst b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> index eaba24320fb2..fd6bb1280e7b 100644
> --- a/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> +++ b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> @@ -16,7 +16,7 @@ SYNOPSIS
>  
>  **bpftool** [*OPTIONS*] **btf** *COMMAND*
>  
> -*OPTIONS* := { |COMMON_OPTIONS| | { **-B** | **--base-btf** } }
> +*OPTIONS* := { |COMMON_OPTIONS| | { **-B** | **--base-btf** } { **-R** | **relocate-base-btf** } }


The double-dash is missing at the beginning of --relocate-base-btf.


>  
>  *COMMANDS* := { **dump** | **help** }
>  
> @@ -85,6 +85,19 @@ OPTIONS
>      BTF object is passed through other handles, this option becomes
>      necessary.
>  
> +-R, --relocate-base-btf *FILE*
> +    When split BTF is generated with distilled base BTF for relocation,
> +    the latter is stored in a .BTF.base section and allows us to later
> +    relocate split BTF and a potentially-changed base BTF by using
> +    information in the .BTF.base section about the base types referenced
> +    from split BTF.  Relocation is carried out against the split BTF
> +    supplied via this parameter and the split BTF will then refer to
> +    the base types supplied in *FILE*.
> +
> +    If this option is not used, split BTF is shown relative to the
> +    .BTF.base, which contains just enough information to support later
> +    relocation.
> +
>  EXAMPLES
>  ========
>  **# bpftool btf dump id 1226**
> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
> index 04afe2ac2228..878cf3d49a76 100644
> --- a/tools/bpf/bpftool/bash-completion/bpftool
> +++ b/tools/bpf/bpftool/bash-completion/bpftool
> @@ -262,7 +262,7 @@ _bpftool()
>      # Deal with options
>      if [[ ${words[cword]} == -* ]]; then
>          local c='--version --json --pretty --bpffs --mapcompat --debug \
> -            --use-loader --base-btf'
> +            --use-loader --base-btf --relocate-base-btf'
>          COMPREPLY=( $( compgen -W "$c" -- "$cur" ) )
>          return 0
>      fi
> @@ -283,7 +283,7 @@ _bpftool()
>              _sysfs_get_netdevs
>              return 0
>              ;;
> -        file|pinned|-B|--base-btf)
> +        file|pinned|-B|-R|--base-btf|--relocate-base-btf)
>              _filedir
>              return 0
>              ;;
> @@ -297,7 +297,8 @@ _bpftool()
>      local i pprev
>      for (( i=1; i < ${#words[@]}; )); do
>          if [[ ${words[i]::1} == - ]] &&
> -            [[ ${words[i]} != "-B" ]] && [[ ${words[i]} != "--base-btf" ]]; then
> +            [[ ${words[i]} != "-B" ]] && [[ ${words[i]} != "--base-btf" ]] &&
> +            [[ ${words[i]} != "-R" ]] && [[ ${words[i]} != "--relocate-base-btf" ]]; then
>              words=( "${words[@]:0:i}" "${words[@]:i+1}" )
>              [[ $i -le $cword ]] && cword=$(( cword - 1 ))
>          else
> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
> index 0ca1f2417801..34f60d9e433d 100644
> --- a/tools/bpf/bpftool/btf.c
> +++ b/tools/bpf/bpftool/btf.c
> @@ -638,6 +638,14 @@ static int do_dump(int argc, char **argv)
>  			base_btf = btf__parse_opts(*argv, &optp);
>  			if (base_btf)
>  				btf = btf__parse_split(*argv, base_btf);
> +			if (btf && relocate_base_btf) {
> +				err = btf__relocate(btf, relocate_base_btf);
> +				if (err) {
> +					p_err("could not relocate BTF from '%s' with base BTF '%s': %s\n",
> +					      *argv, relocate_base_btf_path, strerror(-err));
> +					goto done;
> +				}
> +			}
>  		}
>  		if (!btf) {
>  			err = -errno;
> @@ -1075,7 +1083,8 @@ static int do_help(int argc, char **argv)
>  		"       " HELP_SPEC_MAP "\n"
>  		"       " HELP_SPEC_PROGRAM "\n"
>  		"       " HELP_SPEC_OPTIONS " |\n"
> -		"                    {-B|--base-btf} }\n"
> +		"                    {-B|--base-btf} |\n"
> +		"                    {-R|--relocate-base-btf} }\n"
>  		"",
>  		bin_name, "btf");
>  
> diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
> index 08d0ac543c67..69d4906bec5c 100644
> --- a/tools/bpf/bpftool/main.c
> +++ b/tools/bpf/bpftool/main.c
> @@ -32,6 +32,8 @@ bool verifier_logs;
>  bool relaxed_maps;
>  bool use_loader;
>  struct btf *base_btf;
> +struct btf *relocate_base_btf;
> +const char *relocate_base_btf_path;
>  struct hashmap *refs_table;
>  
>  static void __noreturn clean_and_exit(int i)
> @@ -448,6 +450,7 @@ int main(int argc, char **argv)
>  		{ "debug",	no_argument,	NULL,	'd' },
>  		{ "use-loader",	no_argument,	NULL,	'L' },
>  		{ "base-btf",	required_argument, NULL, 'B' },
> +		{ "relocate-base-btf", required_argument, NULL, 'R' },

Nit: The lines above yours use tabs to visually align the different
fields, would you mind (optionally) re-aligning them, or at least using
tabs in your own line, please?

Other than these, the changes look good to me, thank you

Reviewed-by: Quentin Monnet <qmo@kernel.org>
Alan Maguire May 14, 2024, 4:33 p.m. UTC | #3 
On 13/05/2024 12:12, Quentin Monnet wrote:
> 2024-05-10 11:32 UTC+0100 ~ Alan Maguire <alan.maguire@oracle.com>
>> If the -R <base_btf> option is used, we can display BTF that has been
>> generated with distilled base BTF in its relocated form.  For example
>> for bpf_testmod.ko (which is built as an out-of-tree module, so has
>> a distilled .BTF.base section:
>>
>> bpftool btf dump file bpf_testmod.ko
>>
>> Alternatively, we can display content relocated with
>> (a possibly changed) base BTF via
>>
>> bpftool btf dump -R /sys/kernel/btf/vmlinux bpf_testmod.ko
>>
>> The latter mirrors how the kernel will handle such split
>> BTF; it relocates its representation with the running
>> kernel, and if successful, renumbers BTF ids to reference
>> the current vmlinux BTF.
>>
>> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
>> ---
>>  tools/bpf/bpftool/Documentation/bpftool-btf.rst | 15 ++++++++++++++-
>>  tools/bpf/bpftool/bash-completion/bpftool       |  7 ++++---
>>  tools/bpf/bpftool/btf.c                         | 11 ++++++++++-
>>  tools/bpf/bpftool/main.c                        | 14 +++++++++++++-
>>  tools/bpf/bpftool/main.h                        |  2 ++
>>  5 files changed, 43 insertions(+), 6 deletions(-)
>>
>> diff --git a/tools/bpf/bpftool/Documentation/bpftool-btf.rst b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
>> index eaba24320fb2..fd6bb1280e7b 100644
>> --- a/tools/bpf/bpftool/Documentation/bpftool-btf.rst
>> +++ b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
>> @@ -16,7 +16,7 @@ SYNOPSIS
>>  
>>  **bpftool** [*OPTIONS*] **btf** *COMMAND*
>>  
>> -*OPTIONS* := { |COMMON_OPTIONS| | { **-B** | **--base-btf** } }
>> +*OPTIONS* := { |COMMON_OPTIONS| | { **-B** | **--base-btf** } { **-R** | **relocate-base-btf** } }
> 
> 
> The double-dash is missing at the beginning of --relocate-base-btf.
> 
> 

ah good catch, thanks!

>>  
>>  *COMMANDS* := { **dump** | **help** }
>>  
>> @@ -85,6 +85,19 @@ OPTIONS
>>      BTF object is passed through other handles, this option becomes
>>      necessary.
>>  
>> +-R, --relocate-base-btf *FILE*
>> +    When split BTF is generated with distilled base BTF for relocation,
>> +    the latter is stored in a .BTF.base section and allows us to later
>> +    relocate split BTF and a potentially-changed base BTF by using
>> +    information in the .BTF.base section about the base types referenced
>> +    from split BTF.  Relocation is carried out against the split BTF
>> +    supplied via this parameter and the split BTF will then refer to
>> +    the base types supplied in *FILE*.
>> +
>> +    If this option is not used, split BTF is shown relative to the
>> +    .BTF.base, which contains just enough information to support later
>> +    relocation.
>> +
>>  EXAMPLES
>>  ========
>>  **# bpftool btf dump id 1226**
>> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
>> index 04afe2ac2228..878cf3d49a76 100644
>> --- a/tools/bpf/bpftool/bash-completion/bpftool
>> +++ b/tools/bpf/bpftool/bash-completion/bpftool
>> @@ -262,7 +262,7 @@ _bpftool()
>>      # Deal with options
>>      if [[ ${words[cword]} == -* ]]; then
>>          local c='--version --json --pretty --bpffs --mapcompat --debug \
>> -            --use-loader --base-btf'
>> +            --use-loader --base-btf --relocate-base-btf'
>>          COMPREPLY=( $( compgen -W "$c" -- "$cur" ) )
>>          return 0
>>      fi
>> @@ -283,7 +283,7 @@ _bpftool()
>>              _sysfs_get_netdevs
>>              return 0
>>              ;;
>> -        file|pinned|-B|--base-btf)
>> +        file|pinned|-B|-R|--base-btf|--relocate-base-btf)
>>              _filedir
>>              return 0
>>              ;;
>> @@ -297,7 +297,8 @@ _bpftool()
>>      local i pprev
>>      for (( i=1; i < ${#words[@]}; )); do
>>          if [[ ${words[i]::1} == - ]] &&
>> -            [[ ${words[i]} != "-B" ]] && [[ ${words[i]} != "--base-btf" ]]; then
>> +            [[ ${words[i]} != "-B" ]] && [[ ${words[i]} != "--base-btf" ]] &&
>> +            [[ ${words[i]} != "-R" ]] && [[ ${words[i]} != "--relocate-base-btf" ]]; then
>>              words=( "${words[@]:0:i}" "${words[@]:i+1}" )
>>              [[ $i -le $cword ]] && cword=$(( cword - 1 ))
>>          else
>> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
>> index 0ca1f2417801..34f60d9e433d 100644
>> --- a/tools/bpf/bpftool/btf.c
>> +++ b/tools/bpf/bpftool/btf.c
>> @@ -638,6 +638,14 @@ static int do_dump(int argc, char **argv)
>>  			base_btf = btf__parse_opts(*argv, &optp);
>>  			if (base_btf)
>>  				btf = btf__parse_split(*argv, base_btf);
>> +			if (btf && relocate_base_btf) {
>> +				err = btf__relocate(btf, relocate_base_btf);
>> +				if (err) {
>> +					p_err("could not relocate BTF from '%s' with base BTF '%s': %s\n",
>> +					      *argv, relocate_base_btf_path, strerror(-err));
>> +					goto done;
>> +				}
>> +			}
>>  		}
>>  		if (!btf) {
>>  			err = -errno;
>> @@ -1075,7 +1083,8 @@ static int do_help(int argc, char **argv)
>>  		"       " HELP_SPEC_MAP "\n"
>>  		"       " HELP_SPEC_PROGRAM "\n"
>>  		"       " HELP_SPEC_OPTIONS " |\n"
>> -		"                    {-B|--base-btf} }\n"
>> +		"                    {-B|--base-btf} |\n"
>> +		"                    {-R|--relocate-base-btf} }\n"
>>  		"",
>>  		bin_name, "btf");
>>  
>> diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
>> index 08d0ac543c67..69d4906bec5c 100644
>> --- a/tools/bpf/bpftool/main.c
>> +++ b/tools/bpf/bpftool/main.c
>> @@ -32,6 +32,8 @@ bool verifier_logs;
>>  bool relaxed_maps;
>>  bool use_loader;
>>  struct btf *base_btf;
>> +struct btf *relocate_base_btf;
>> +const char *relocate_base_btf_path;
>>  struct hashmap *refs_table;
>>  
>>  static void __noreturn clean_and_exit(int i)
>> @@ -448,6 +450,7 @@ int main(int argc, char **argv)
>>  		{ "debug",	no_argument,	NULL,	'd' },
>>  		{ "use-loader",	no_argument,	NULL,	'L' },
>>  		{ "base-btf",	required_argument, NULL, 'B' },
>> +		{ "relocate-base-btf", required_argument, NULL, 'R' },
> 
> Nit: The lines above yours use tabs to visually align the different
> fields, would you mind (optionally) re-aligning them, or at least using
> tabs in your own line, please?
>

Sure, will do.

> Other than these, the changes look good to me, thank you
> 
> Reviewed-by: Quentin Monnet <qmo@kernel.org>
> 

Thanks for reviewing!
diff mbox series

Patch

diff --git a/tools/bpf/bpftool/Documentation/bpftool-btf.rst b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
index eaba24320fb2..fd6bb1280e7b 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-btf.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
@@ -16,7 +16,7 @@  SYNOPSIS
 
 **bpftool** [*OPTIONS*] **btf** *COMMAND*
 
-*OPTIONS* := { |COMMON_OPTIONS| | { **-B** | **--base-btf** } }
+*OPTIONS* := { |COMMON_OPTIONS| | { **-B** | **--base-btf** } { **-R** | **relocate-base-btf** } }
 
 *COMMANDS* := { **dump** | **help** }
 
@@ -85,6 +85,19 @@  OPTIONS
     BTF object is passed through other handles, this option becomes
     necessary.
 
+-R, --relocate-base-btf *FILE*
+    When split BTF is generated with distilled base BTF for relocation,
+    the latter is stored in a .BTF.base section and allows us to later
+    relocate split BTF and a potentially-changed base BTF by using
+    information in the .BTF.base section about the base types referenced
+    from split BTF.  Relocation is carried out against the split BTF
+    supplied via this parameter and the split BTF will then refer to
+    the base types supplied in *FILE*.
+
+    If this option is not used, split BTF is shown relative to the
+    .BTF.base, which contains just enough information to support later
+    relocation.
+
 EXAMPLES
 ========
 **# bpftool btf dump id 1226**
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index 04afe2ac2228..878cf3d49a76 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -262,7 +262,7 @@  _bpftool()
     # Deal with options
     if [[ ${words[cword]} == -* ]]; then
         local c='--version --json --pretty --bpffs --mapcompat --debug \
-            --use-loader --base-btf'
+            --use-loader --base-btf --relocate-base-btf'
         COMPREPLY=( $( compgen -W "$c" -- "$cur" ) )
         return 0
     fi
@@ -283,7 +283,7 @@  _bpftool()
             _sysfs_get_netdevs
             return 0
             ;;
-        file|pinned|-B|--base-btf)
+        file|pinned|-B|-R|--base-btf|--relocate-base-btf)
             _filedir
             return 0
             ;;
@@ -297,7 +297,8 @@  _bpftool()
     local i pprev
     for (( i=1; i < ${#words[@]}; )); do
         if [[ ${words[i]::1} == - ]] &&
-            [[ ${words[i]} != "-B" ]] && [[ ${words[i]} != "--base-btf" ]]; then
+            [[ ${words[i]} != "-B" ]] && [[ ${words[i]} != "--base-btf" ]] &&
+            [[ ${words[i]} != "-R" ]] && [[ ${words[i]} != "--relocate-base-btf" ]]; then
             words=( "${words[@]:0:i}" "${words[@]:i+1}" )
             [[ $i -le $cword ]] && cword=$(( cword - 1 ))
         else
diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index 0ca1f2417801..34f60d9e433d 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -638,6 +638,14 @@  static int do_dump(int argc, char **argv)
 			base_btf = btf__parse_opts(*argv, &optp);
 			if (base_btf)
 				btf = btf__parse_split(*argv, base_btf);
+			if (btf && relocate_base_btf) {
+				err = btf__relocate(btf, relocate_base_btf);
+				if (err) {
+					p_err("could not relocate BTF from '%s' with base BTF '%s': %s\n",
+					      *argv, relocate_base_btf_path, strerror(-err));
+					goto done;
+				}
+			}
 		}
 		if (!btf) {
 			err = -errno;
@@ -1075,7 +1083,8 @@  static int do_help(int argc, char **argv)
 		"       " HELP_SPEC_MAP "\n"
 		"       " HELP_SPEC_PROGRAM "\n"
 		"       " HELP_SPEC_OPTIONS " |\n"
-		"                    {-B|--base-btf} }\n"
+		"                    {-B|--base-btf} |\n"
+		"                    {-R|--relocate-base-btf} }\n"
 		"",
 		bin_name, "btf");
 
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 08d0ac543c67..69d4906bec5c 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -32,6 +32,8 @@  bool verifier_logs;
 bool relaxed_maps;
 bool use_loader;
 struct btf *base_btf;
+struct btf *relocate_base_btf;
+const char *relocate_base_btf_path;
 struct hashmap *refs_table;
 
 static void __noreturn clean_and_exit(int i)
@@ -448,6 +450,7 @@  int main(int argc, char **argv)
 		{ "debug",	no_argument,	NULL,	'd' },
 		{ "use-loader",	no_argument,	NULL,	'L' },
 		{ "base-btf",	required_argument, NULL, 'B' },
+		{ "relocate-base-btf", required_argument, NULL, 'R' },
 		{ 0 }
 	};
 	bool version_requested = false;
@@ -473,7 +476,7 @@  int main(int argc, char **argv)
 	bin_name = "bpftool";
 
 	opterr = 0;
-	while ((opt = getopt_long(argc, argv, "VhpjfLmndB:l",
+	while ((opt = getopt_long(argc, argv, "VhpjfLmndB:lR:",
 				  options, NULL)) >= 0) {
 		switch (opt) {
 		case 'V':
@@ -519,6 +522,15 @@  int main(int argc, char **argv)
 		case 'L':
 			use_loader = true;
 			break;
+		case 'R':
+			relocate_base_btf_path = optarg;
+			relocate_base_btf = btf__parse(optarg, NULL);
+			if (!relocate_base_btf) {
+				p_err("failed to parse base BTF for relocation at '%s': %d\n",
+				      optarg, -errno);
+				return -1;
+			}
+			break;
 		default:
 			p_err("unrecognized option '%s'", argv[optind - 1]);
 			if (json_output)
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 9eb764fe4cc8..bbf8194a2d76 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -83,6 +83,8 @@  extern bool verifier_logs;
 extern bool relaxed_maps;
 extern bool use_loader;
 extern struct btf *base_btf;
+extern struct btf *relocate_base_btf;
+extern const char *relocate_base_btf_path;
 extern struct hashmap *refs_table;
 
 void __printf(1, 2) p_err(const char *fmt, ...);