* [PATCH] docs/bpf: Add constant values for linkages
@ 2024-08-19 22:30 ` Will Hawkins
0 siblings, 0 replies; 6+ messages in thread
From: Will Hawkins @ 2024-08-19 22:30 UTC (permalink / raw)
To: bpf, bpf; +Cc: Will Hawkins
Make the values of the symbolic constants that define the valid linkages
for functions and variables explicit.
Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
---
Documentation/bpf/btf.rst | 44 +++++++++++++++++++++++++++++++++++----
1 file changed, 40 insertions(+), 4 deletions(-)
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index 257a7e1cdf5d..cce03f1e552a 100644
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -368,7 +368,7 @@ No additional type data follow ``btf_type``.
* ``info.kind_flag``: 0
* ``info.kind``: BTF_KIND_FUNC
* ``info.vlen``: linkage information (BTF_FUNC_STATIC, BTF_FUNC_GLOBAL
- or BTF_FUNC_EXTERN)
+ or BTF_FUNC_EXTERN - see :ref:`BTF_Function_Linkage_Constants`)
* ``type``: a BTF_KIND_FUNC_PROTO type
No additional type data follow ``btf_type``.
@@ -424,9 +424,9 @@ following data::
__u32 linkage;
};
-``struct btf_var`` encoding:
- * ``linkage``: currently only static variable 0, or globally allocated
- variable in ELF sections 1
+``btf_var.linkage`` may take the values: BTF_VAR_STATIC (for a static variable),
+or BTF_VAR_GLOBAL_ALLOCATED (for a globally allocated variable stored in ELF sections 1) -
+see :ref:`BTF_Var_Linkage_Constants`.
Not all type of global variables are supported by LLVM at this point.
The following is currently available:
@@ -549,6 +549,42 @@ The ``btf_enum64`` encoding:
If the original enum value is signed and the size is less than 8,
that value will be sign extended into 8 bytes.
+2.3 Constant Values
+-------------------
+
+.. _BTF_Function_Linkage_Constants:
+
+2.3.1 Function Linkage Constant Values
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.. list-table::
+ :widths: 1 1
+ :header-rows: 1
+
+ * - Name
+ - Value
+ * - ``BTF_FUNC_STATIC``
+ - ``0``
+ * - ``BTF_FUNC_GLOBAL``
+ - ``1``
+ * - ``BTF_FUNC_EXTERN``
+ - ``2``
+
+.. _BTF_Var_Linkage_Constants:
+
+2.3.2 Variable Linkage Constant Values
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.. list-table::
+ :widths: 1 1
+ :header-rows: 1
+
+ * - Name
+ - Value
+ * - ``BTF_VAR_STATIC``
+ - ``0``
+ * - ``BTF_VAR_GLOBAL_ALLOCATED``
+ - ``1``
+
+
3. BTF Kernel API
=================
--
2.45.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [Bpf] [PATCH] docs/bpf: Add constant values for linkages
@ 2024-08-19 22:30 ` Will Hawkins
0 siblings, 0 replies; 6+ messages in thread
From: Will Hawkins @ 2024-08-19 22:30 UTC (permalink / raw)
To: bpf, bpf; +Cc: Will Hawkins
Make the values of the symbolic constants that define the valid linkages
for functions and variables explicit.
Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
---
Documentation/bpf/btf.rst | 44 +++++++++++++++++++++++++++++++++++----
1 file changed, 40 insertions(+), 4 deletions(-)
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index 257a7e1cdf5d..cce03f1e552a 100644
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -368,7 +368,7 @@ No additional type data follow ``btf_type``.
* ``info.kind_flag``: 0
* ``info.kind``: BTF_KIND_FUNC
* ``info.vlen``: linkage information (BTF_FUNC_STATIC, BTF_FUNC_GLOBAL
- or BTF_FUNC_EXTERN)
+ or BTF_FUNC_EXTERN - see :ref:`BTF_Function_Linkage_Constants`)
* ``type``: a BTF_KIND_FUNC_PROTO type
No additional type data follow ``btf_type``.
@@ -424,9 +424,9 @@ following data::
__u32 linkage;
};
-``struct btf_var`` encoding:
- * ``linkage``: currently only static variable 0, or globally allocated
- variable in ELF sections 1
+``btf_var.linkage`` may take the values: BTF_VAR_STATIC (for a static variable),
+or BTF_VAR_GLOBAL_ALLOCATED (for a globally allocated variable stored in ELF sections 1) -
+see :ref:`BTF_Var_Linkage_Constants`.
Not all type of global variables are supported by LLVM at this point.
The following is currently available:
@@ -549,6 +549,42 @@ The ``btf_enum64`` encoding:
If the original enum value is signed and the size is less than 8,
that value will be sign extended into 8 bytes.
+2.3 Constant Values
+-------------------
+
+.. _BTF_Function_Linkage_Constants:
+
+2.3.1 Function Linkage Constant Values
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.. list-table::
+ :widths: 1 1
+ :header-rows: 1
+
+ * - Name
+ - Value
+ * - ``BTF_FUNC_STATIC``
+ - ``0``
+ * - ``BTF_FUNC_GLOBAL``
+ - ``1``
+ * - ``BTF_FUNC_EXTERN``
+ - ``2``
+
+.. _BTF_Var_Linkage_Constants:
+
+2.3.2 Variable Linkage Constant Values
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.. list-table::
+ :widths: 1 1
+ :header-rows: 1
+
+ * - Name
+ - Value
+ * - ``BTF_VAR_STATIC``
+ - ``0``
+ * - ``BTF_VAR_GLOBAL_ALLOCATED``
+ - ``1``
+
+
3. BTF Kernel API
=================
--
2.45.2
--
Bpf mailing list -- bpf@ietf.org
To unsubscribe send an email to bpf-leave@ietf.org
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] docs/bpf: Add constant values for linkages
@ 2024-08-21 21:29 ` Yonghong Song
0 siblings, 0 replies; 6+ messages in thread
From: Yonghong Song @ 2024-08-21 21:29 UTC (permalink / raw)
To: Will Hawkins, bpf, bpf
On 8/19/24 3:30 PM, Will Hawkins wrote:
> Make the values of the symbolic constants that define the valid linkages
> for functions and variables explicit.
>
> Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
> ---
> Documentation/bpf/btf.rst | 44 +++++++++++++++++++++++++++++++++++----
> 1 file changed, 40 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
> index 257a7e1cdf5d..cce03f1e552a 100644
> --- a/Documentation/bpf/btf.rst
> +++ b/Documentation/bpf/btf.rst
> @@ -368,7 +368,7 @@ No additional type data follow ``btf_type``.
> * ``info.kind_flag``: 0
> * ``info.kind``: BTF_KIND_FUNC
> * ``info.vlen``: linkage information (BTF_FUNC_STATIC, BTF_FUNC_GLOBAL
> - or BTF_FUNC_EXTERN)
> + or BTF_FUNC_EXTERN - see :ref:`BTF_Function_Linkage_Constants`)
> * ``type``: a BTF_KIND_FUNC_PROTO type
>
> No additional type data follow ``btf_type``.
> @@ -424,9 +424,9 @@ following data::
> __u32 linkage;
> };
>
> -``struct btf_var`` encoding:
> - * ``linkage``: currently only static variable 0, or globally allocated
> - variable in ELF sections 1
> +``btf_var.linkage`` may take the values: BTF_VAR_STATIC (for a static variable),
> +or BTF_VAR_GLOBAL_ALLOCATED (for a globally allocated variable stored in ELF sections 1) -
Let us remove the above '1', just say '(... stored in explicit ELF sections)'.
Actually, for btf_var linkage, we actually have 3 values. See
enum {
BTF_VAR_STATIC = 0,
BTF_VAR_GLOBAL_ALLOCATED = 1,
BTF_VAR_GLOBAL_EXTERN = 2,
};
See https://github.com/torvalds/linux/blob/master/include/uapi/linux/btf.h#L150-L154
Similar to BTF_VAR_GLOBAL_ALLOCATED, BTF_VAR_GLOBAL_EXTERN is encoded in datasec only
if the variable is stored in explicit ELF sections.
Since you are touching this doc, could you add BTF_VAR_GLOBAL_EXTERN as well?
> +see :ref:`BTF_Var_Linkage_Constants`.
>
> Not all type of global variables are supported by LLVM at this point.
> The following is currently available:
> @@ -549,6 +549,42 @@ The ``btf_enum64`` encoding:
> If the original enum value is signed and the size is less than 8,
> that value will be sign extended into 8 bytes.
>
> +2.3 Constant Values
> +-------------------
> +
> +.. _BTF_Function_Linkage_Constants:
> +
> +2.3.1 Function Linkage Constant Values
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +.. list-table::
> + :widths: 1 1
> + :header-rows: 1
> +
> + * - Name
> + - Value
> + * - ``BTF_FUNC_STATIC``
> + - ``0``
> + * - ``BTF_FUNC_GLOBAL``
> + - ``1``
> + * - ``BTF_FUNC_EXTERN``
> + - ``2``
> +
> +.. _BTF_Var_Linkage_Constants:
> +
> +2.3.2 Variable Linkage Constant Values
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +.. list-table::
> + :widths: 1 1
> + :header-rows: 1
> +
> + * - Name
> + - Value
> + * - ``BTF_VAR_STATIC``
> + - ``0``
> + * - ``BTF_VAR_GLOBAL_ALLOCATED``
> + - ``1``
> +
> +
Form the above, could you use similar format as in Documentation/bpf/standardization/instruction-set.rst? For example,
.. table:: Instruction class
===== ===== =============================== ===================================
class value description reference
===== ===== =============================== ===================================
LD 0x0 non-standard load operations `Load and store instructions`_
LDX 0x1 load into register operations `Load and store instructions`_
ST 0x2 store from immediate operations `Load and store instructions`_
STX 0x3 store from register operations `Load and store instructions`_
ALU 0x4 32-bit arithmetic operations `Arithmetic and jump instructions`_
JMP 0x5 64-bit jump operations `Arithmetic and jump instructions`_
JMP32 0x6 32-bit jump operations `Arithmetic and jump instructions`_
ALU64 0x7 64-bit arithmetic operations `Arithmetic and jump instructions`_
===== ===== =============================== ===================================
I would like we have consistant table presentation between instruction set and btf.
> 3. BTF Kernel API
> =================
>
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bpf] Re: [PATCH] docs/bpf: Add constant values for linkages
@ 2024-08-21 21:29 ` Yonghong Song
0 siblings, 0 replies; 6+ messages in thread
From: Yonghong Song @ 2024-08-21 21:29 UTC (permalink / raw)
To: Will Hawkins, bpf, bpf
On 8/19/24 3:30 PM, Will Hawkins wrote:
> Make the values of the symbolic constants that define the valid linkages
> for functions and variables explicit.
>
> Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
> ---
> Documentation/bpf/btf.rst | 44 +++++++++++++++++++++++++++++++++++----
> 1 file changed, 40 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
> index 257a7e1cdf5d..cce03f1e552a 100644
> --- a/Documentation/bpf/btf.rst
> +++ b/Documentation/bpf/btf.rst
> @@ -368,7 +368,7 @@ No additional type data follow ``btf_type``.
> * ``info.kind_flag``: 0
> * ``info.kind``: BTF_KIND_FUNC
> * ``info.vlen``: linkage information (BTF_FUNC_STATIC, BTF_FUNC_GLOBAL
> - or BTF_FUNC_EXTERN)
> + or BTF_FUNC_EXTERN - see :ref:`BTF_Function_Linkage_Constants`)
> * ``type``: a BTF_KIND_FUNC_PROTO type
>
> No additional type data follow ``btf_type``.
> @@ -424,9 +424,9 @@ following data::
> __u32 linkage;
> };
>
> -``struct btf_var`` encoding:
> - * ``linkage``: currently only static variable 0, or globally allocated
> - variable in ELF sections 1
> +``btf_var.linkage`` may take the values: BTF_VAR_STATIC (for a static variable),
> +or BTF_VAR_GLOBAL_ALLOCATED (for a globally allocated variable stored in ELF sections 1) -
Let us remove the above '1', just say '(... stored in explicit ELF sections)'.
Actually, for btf_var linkage, we actually have 3 values. See
enum {
BTF_VAR_STATIC = 0,
BTF_VAR_GLOBAL_ALLOCATED = 1,
BTF_VAR_GLOBAL_EXTERN = 2,
};
See https://github.com/torvalds/linux/blob/master/include/uapi/linux/btf.h#L150-L154
Similar to BTF_VAR_GLOBAL_ALLOCATED, BTF_VAR_GLOBAL_EXTERN is encoded in datasec only
if the variable is stored in explicit ELF sections.
Since you are touching this doc, could you add BTF_VAR_GLOBAL_EXTERN as well?
> +see :ref:`BTF_Var_Linkage_Constants`.
>
> Not all type of global variables are supported by LLVM at this point.
> The following is currently available:
> @@ -549,6 +549,42 @@ The ``btf_enum64`` encoding:
> If the original enum value is signed and the size is less than 8,
> that value will be sign extended into 8 bytes.
>
> +2.3 Constant Values
> +-------------------
> +
> +.. _BTF_Function_Linkage_Constants:
> +
> +2.3.1 Function Linkage Constant Values
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +.. list-table::
> + :widths: 1 1
> + :header-rows: 1
> +
> + * - Name
> + - Value
> + * - ``BTF_FUNC_STATIC``
> + - ``0``
> + * - ``BTF_FUNC_GLOBAL``
> + - ``1``
> + * - ``BTF_FUNC_EXTERN``
> + - ``2``
> +
> +.. _BTF_Var_Linkage_Constants:
> +
> +2.3.2 Variable Linkage Constant Values
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +.. list-table::
> + :widths: 1 1
> + :header-rows: 1
> +
> + * - Name
> + - Value
> + * - ``BTF_VAR_STATIC``
> + - ``0``
> + * - ``BTF_VAR_GLOBAL_ALLOCATED``
> + - ``1``
> +
> +
Form the above, could you use similar format as in Documentation/bpf/standardization/instruction-set.rst? For example,
.. table:: Instruction class
===== ===== =============================== ===================================
class value description reference
===== ===== =============================== ===================================
LD 0x0 non-standard load operations `Load and store instructions`_
LDX 0x1 load into register operations `Load and store instructions`_
ST 0x2 store from immediate operations `Load and store instructions`_
STX 0x3 store from register operations `Load and store instructions`_
ALU 0x4 32-bit arithmetic operations `Arithmetic and jump instructions`_
JMP 0x5 64-bit jump operations `Arithmetic and jump instructions`_
JMP32 0x6 32-bit jump operations `Arithmetic and jump instructions`_
ALU64 0x7 64-bit arithmetic operations `Arithmetic and jump instructions`_
===== ===== =============================== ===================================
I would like we have consistant table presentation between instruction set and btf.
> 3. BTF Kernel API
> =================
>
--
Bpf mailing list -- bpf@ietf.org
To unsubscribe send an email to bpf-leave@ietf.org
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] docs/bpf: Add constant values for linkages
@ 2024-08-21 21:35 ` Will Hawkins
0 siblings, 0 replies; 6+ messages in thread
From: Will Hawkins @ 2024-08-21 21:35 UTC (permalink / raw)
To: Yonghong Song; +Cc: bpf, bpf
On Wed, Aug 21, 2024 at 5:30 PM Yonghong Song <yonghong.song@linux.dev> wrote:
>
>
> On 8/19/24 3:30 PM, Will Hawkins wrote:
> > Make the values of the symbolic constants that define the valid linkages
> > for functions and variables explicit.
> >
> > Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
> > ---
> > Documentation/bpf/btf.rst | 44 +++++++++++++++++++++++++++++++++++----
> > 1 file changed, 40 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
> > index 257a7e1cdf5d..cce03f1e552a 100644
> > --- a/Documentation/bpf/btf.rst
> > +++ b/Documentation/bpf/btf.rst
> > @@ -368,7 +368,7 @@ No additional type data follow ``btf_type``.
> > * ``info.kind_flag``: 0
> > * ``info.kind``: BTF_KIND_FUNC
> > * ``info.vlen``: linkage information (BTF_FUNC_STATIC, BTF_FUNC_GLOBAL
> > - or BTF_FUNC_EXTERN)
> > + or BTF_FUNC_EXTERN - see :ref:`BTF_Function_Linkage_Constants`)
> > * ``type``: a BTF_KIND_FUNC_PROTO type
> >
> > No additional type data follow ``btf_type``.
> > @@ -424,9 +424,9 @@ following data::
> > __u32 linkage;
> > };
> >
> > -``struct btf_var`` encoding:
> > - * ``linkage``: currently only static variable 0, or globally allocated
> > - variable in ELF sections 1
> > +``btf_var.linkage`` may take the values: BTF_VAR_STATIC (for a static variable),
> > +or BTF_VAR_GLOBAL_ALLOCATED (for a globally allocated variable stored in ELF sections 1) -
>
> Let us remove the above '1', just say '(... stored in explicit ELF sections)'.
Great! I only kept that because it was there in the existing documentation!
>
> Actually, for btf_var linkage, we actually have 3 values. See
>
> enum {
> BTF_VAR_STATIC = 0,
> BTF_VAR_GLOBAL_ALLOCATED = 1,
> BTF_VAR_GLOBAL_EXTERN = 2,
> };
>
> See https://github.com/torvalds/linux/blob/master/include/uapi/linux/btf.h#L150-L154
>
Great! I will make that update!
> Similar to BTF_VAR_GLOBAL_ALLOCATED, BTF_VAR_GLOBAL_EXTERN is encoded in datasec only
> if the variable is stored in explicit ELF sections.
>
> Since you are touching this doc, could you add BTF_VAR_GLOBAL_EXTERN as well?
>
Of course!
> > +see :ref:`BTF_Var_Linkage_Constants`.
> >
> > Not all type of global variables are supported by LLVM at this point.
> > The following is currently available:
> > @@ -549,6 +549,42 @@ The ``btf_enum64`` encoding:
> > If the original enum value is signed and the size is less than 8,
> > that value will be sign extended into 8 bytes.
> >
> > +2.3 Constant Values
> > +-------------------
> > +
> > +.. _BTF_Function_Linkage_Constants:
> > +
> > +2.3.1 Function Linkage Constant Values
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > +.. list-table::
> > + :widths: 1 1
> > + :header-rows: 1
> > +
> > + * - Name
> > + - Value
> > + * - ``BTF_FUNC_STATIC``
> > + - ``0``
> > + * - ``BTF_FUNC_GLOBAL``
> > + - ``1``
> > + * - ``BTF_FUNC_EXTERN``
> > + - ``2``
> > +
> > +.. _BTF_Var_Linkage_Constants:
> > +
> > +2.3.2 Variable Linkage Constant Values
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > +.. list-table::
> > + :widths: 1 1
> > + :header-rows: 1
> > +
> > + * - Name
> > + - Value
> > + * - ``BTF_VAR_STATIC``
> > + - ``0``
> > + * - ``BTF_VAR_GLOBAL_ALLOCATED``
> > + - ``1``
> > +
> > +
>
> Form the above, could you use similar format as in Documentation/bpf/standardization/instruction-set.rst? For example,
>
> .. table:: Instruction class
>
> ===== ===== =============================== ===================================
> class value description reference
> ===== ===== =============================== ===================================
> LD 0x0 non-standard load operations `Load and store instructions`_
> LDX 0x1 load into register operations `Load and store instructions`_
> ST 0x2 store from immediate operations `Load and store instructions`_
> STX 0x3 store from register operations `Load and store instructions`_
> ALU 0x4 32-bit arithmetic operations `Arithmetic and jump instructions`_
> JMP 0x5 64-bit jump operations `Arithmetic and jump instructions`_
> JMP32 0x6 32-bit jump operations `Arithmetic and jump instructions`_
> ALU64 0x7 64-bit arithmetic operations `Arithmetic and jump instructions`_
> ===== ===== =============================== ===================================
>
> I would like we have consistant table presentation between instruction set and btf.
>
Absolutely. I volunteered to edit the document that will ultimately
turn into the IETF spec draft for BTF and this is the first fix that
jumped out to me when I was proofreading.
Thank you for the review! I will have a v2 of the patch in just a few minutes!
Thank you, again!
Will
> > 3. BTF Kernel API
> > =================
> >
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bpf] Re: [PATCH] docs/bpf: Add constant values for linkages
@ 2024-08-21 21:35 ` Will Hawkins
0 siblings, 0 replies; 6+ messages in thread
From: Will Hawkins @ 2024-08-21 21:35 UTC (permalink / raw)
To: Yonghong Song; +Cc: bpf, bpf
On Wed, Aug 21, 2024 at 5:30 PM Yonghong Song <yonghong.song@linux.dev> wrote:
>
>
> On 8/19/24 3:30 PM, Will Hawkins wrote:
> > Make the values of the symbolic constants that define the valid linkages
> > for functions and variables explicit.
> >
> > Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
> > ---
> > Documentation/bpf/btf.rst | 44 +++++++++++++++++++++++++++++++++++----
> > 1 file changed, 40 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
> > index 257a7e1cdf5d..cce03f1e552a 100644
> > --- a/Documentation/bpf/btf.rst
> > +++ b/Documentation/bpf/btf.rst
> > @@ -368,7 +368,7 @@ No additional type data follow ``btf_type``.
> > * ``info.kind_flag``: 0
> > * ``info.kind``: BTF_KIND_FUNC
> > * ``info.vlen``: linkage information (BTF_FUNC_STATIC, BTF_FUNC_GLOBAL
> > - or BTF_FUNC_EXTERN)
> > + or BTF_FUNC_EXTERN - see :ref:`BTF_Function_Linkage_Constants`)
> > * ``type``: a BTF_KIND_FUNC_PROTO type
> >
> > No additional type data follow ``btf_type``.
> > @@ -424,9 +424,9 @@ following data::
> > __u32 linkage;
> > };
> >
> > -``struct btf_var`` encoding:
> > - * ``linkage``: currently only static variable 0, or globally allocated
> > - variable in ELF sections 1
> > +``btf_var.linkage`` may take the values: BTF_VAR_STATIC (for a static variable),
> > +or BTF_VAR_GLOBAL_ALLOCATED (for a globally allocated variable stored in ELF sections 1) -
>
> Let us remove the above '1', just say '(... stored in explicit ELF sections)'.
Great! I only kept that because it was there in the existing documentation!
>
> Actually, for btf_var linkage, we actually have 3 values. See
>
> enum {
> BTF_VAR_STATIC = 0,
> BTF_VAR_GLOBAL_ALLOCATED = 1,
> BTF_VAR_GLOBAL_EXTERN = 2,
> };
>
> See https://github.com/torvalds/linux/blob/master/include/uapi/linux/btf.h#L150-L154
>
Great! I will make that update!
> Similar to BTF_VAR_GLOBAL_ALLOCATED, BTF_VAR_GLOBAL_EXTERN is encoded in datasec only
> if the variable is stored in explicit ELF sections.
>
> Since you are touching this doc, could you add BTF_VAR_GLOBAL_EXTERN as well?
>
Of course!
> > +see :ref:`BTF_Var_Linkage_Constants`.
> >
> > Not all type of global variables are supported by LLVM at this point.
> > The following is currently available:
> > @@ -549,6 +549,42 @@ The ``btf_enum64`` encoding:
> > If the original enum value is signed and the size is less than 8,
> > that value will be sign extended into 8 bytes.
> >
> > +2.3 Constant Values
> > +-------------------
> > +
> > +.. _BTF_Function_Linkage_Constants:
> > +
> > +2.3.1 Function Linkage Constant Values
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > +.. list-table::
> > + :widths: 1 1
> > + :header-rows: 1
> > +
> > + * - Name
> > + - Value
> > + * - ``BTF_FUNC_STATIC``
> > + - ``0``
> > + * - ``BTF_FUNC_GLOBAL``
> > + - ``1``
> > + * - ``BTF_FUNC_EXTERN``
> > + - ``2``
> > +
> > +.. _BTF_Var_Linkage_Constants:
> > +
> > +2.3.2 Variable Linkage Constant Values
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > +.. list-table::
> > + :widths: 1 1
> > + :header-rows: 1
> > +
> > + * - Name
> > + - Value
> > + * - ``BTF_VAR_STATIC``
> > + - ``0``
> > + * - ``BTF_VAR_GLOBAL_ALLOCATED``
> > + - ``1``
> > +
> > +
>
> Form the above, could you use similar format as in Documentation/bpf/standardization/instruction-set.rst? For example,
>
> .. table:: Instruction class
>
> ===== ===== =============================== ===================================
> class value description reference
> ===== ===== =============================== ===================================
> LD 0x0 non-standard load operations `Load and store instructions`_
> LDX 0x1 load into register operations `Load and store instructions`_
> ST 0x2 store from immediate operations `Load and store instructions`_
> STX 0x3 store from register operations `Load and store instructions`_
> ALU 0x4 32-bit arithmetic operations `Arithmetic and jump instructions`_
> JMP 0x5 64-bit jump operations `Arithmetic and jump instructions`_
> JMP32 0x6 32-bit jump operations `Arithmetic and jump instructions`_
> ALU64 0x7 64-bit arithmetic operations `Arithmetic and jump instructions`_
> ===== ===== =============================== ===================================
>
> I would like we have consistant table presentation between instruction set and btf.
>
Absolutely. I volunteered to edit the document that will ultimately
turn into the IETF spec draft for BTF and this is the first fix that
jumped out to me when I was proofreading.
Thank you for the review! I will have a v2 of the patch in just a few minutes!
Thank you, again!
Will
> > 3. BTF Kernel API
> > =================
> >
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2024-08-19 22:30 [PATCH] docs/bpf: Add constant values for linkages Will Hawkins
2024-08-19 22:30 ` [Bpf] " Will Hawkins
2024-08-21 21:29 ` Yonghong Song
2024-08-21 21:29 ` [Bpf] " Yonghong Song
2024-08-21 21:35 ` Will Hawkins
2024-08-21 21:35 ` [Bpf] " Will Hawkins
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