diff mbox

[v3,1/2] arm: kernel: Add SMC structure parameter

Message ID 1484173918-25090-2-git-send-email-andy.gross@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Andy Gross Jan. 11, 2017, 10:31 p.m. UTC 
This patch adds a quirk parameter to the arm_smccc_smc call.  The quirk
structure allows for specialized SMC operations due to SoC specific
requirements.  The current arm_smccc_smc is renamed and macros are used
instead to specify the standard arm_smccc_smc or the arm_smccc_smc_quirk
function.

This patch and partial implementation was suggested by Will Deacon.

Signed-off-by: Andy Gross <andy.gross@linaro.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/kernel/armksyms.c      |  2 +-
 arch/arm/kernel/smccc-call.S    |  7 ++++---
 arch/arm64/kernel/arm64ksyms.c  |  2 +-
 arch/arm64/kernel/asm-offsets.c |  7 +++++--
 arch/arm64/kernel/smccc-call.S  |  7 ++++---
 include/linux/arm-smccc.h       | 26 ++++++++++++++++++++++----
 6 files changed, 37 insertions(+), 14 deletions(-)

Comments

Russell King (Oracle) Jan. 19, 2017, 2:40 p.m. UTC | #1 
On Wed, Jan 11, 2017 at 04:31:57PM -0600, Andy Gross wrote:
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index b5abfda..3e28d08 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -72,19 +72,33 @@ struct arm_smccc_res {
>  };
>  
>  /**
> - * arm_smccc_smc() - make SMC calls
> + * struct arm_smccc_quirk - Contains quirk information
> + * id contains quirk identification
> + * state contains the quirk specific information

Given that this is a kerneldoc comment, it should really conform to the
kerneldoc requirements - see Documentation/kernel-doc-nano-HOWTO.txt:

/**
 * struct arm_smccc_quirk - Contains quirk information
 * @id: quirk identification
 * @state: the quirk specific information

> + */
> +struct arm_smccc_quirk {
> +	int	id;
> +	union {
> +		unsigned long a6;
> +	} state;
> +};
> +
> +/**
> + * __arm_smccc_smc() - make SMC calls
>   * @a0-a7: arguments passed in registers 0 to 7
>   * @res: result values from registers 0 to 3
> + * @quirk: optional quirk structure
>   *
>   * This function is used to make SMC calls following SMC Calling Convention.
>   * The content of the supplied param are copied to registers 0 to 7 prior
>   * to the SMC instruction. The return values are updated with the content
> - * from register 0 to 3 on return from the SMC instruction.
> + * from register 0 to 3 on return from the SMC instruction.  An optional
> + * quirk structure provides vendor specific behavior.

It's quite odd to have the result buried in the middle of arguments
passed to a function, but I guess for the sake of simplicity in the
assembly code that's what we need.

Also:

"@quirk points to an arm_smccc_quirk, or NULL when no quirks are required."

And... should this not be const?  Are we expecting anyone to modify
the quirk structure?

Thanks.
Andy Gross Jan. 19, 2017, 3:45 p.m. UTC | #2 
On Thu, Jan 19, 2017 at 02:40:08PM +0000, Russell King - ARM Linux wrote:
> On Wed, Jan 11, 2017 at 04:31:57PM -0600, Andy Gross wrote:
> > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> > index b5abfda..3e28d08 100644
> > --- a/include/linux/arm-smccc.h
> > +++ b/include/linux/arm-smccc.h
> > @@ -72,19 +72,33 @@ struct arm_smccc_res {
> >  };
> >  
> >  /**
> > - * arm_smccc_smc() - make SMC calls
> > + * struct arm_smccc_quirk - Contains quirk information
> > + * id contains quirk identification
> > + * state contains the quirk specific information
> 
> Given that this is a kerneldoc comment, it should really conform to the
> kerneldoc requirements - see Documentation/kernel-doc-nano-HOWTO.txt:
> 
> /**
>  * struct arm_smccc_quirk - Contains quirk information
>  * @id: quirk identification
>  * @state: the quirk specific information

Ah, I flubbed that.  I'll fix this.

> 
> > + */
> > +struct arm_smccc_quirk {
> > +	int	id;
> > +	union {
> > +		unsigned long a6;
> > +	} state;
> > +};
> > +
> > +/**
> > + * __arm_smccc_smc() - make SMC calls
> >   * @a0-a7: arguments passed in registers 0 to 7
> >   * @res: result values from registers 0 to 3
> > + * @quirk: optional quirk structure
> >   *
> >   * This function is used to make SMC calls following SMC Calling Convention.
> >   * The content of the supplied param are copied to registers 0 to 7 prior
> >   * to the SMC instruction. The return values are updated with the content
> > - * from register 0 to 3 on return from the SMC instruction.
> > + * from register 0 to 3 on return from the SMC instruction.  An optional
> > + * quirk structure provides vendor specific behavior.
> 
> It's quite odd to have the result buried in the middle of arguments
> passed to a function, but I guess for the sake of simplicity in the
> assembly code that's what we need.
> 
> Also:
> 
> "@quirk points to an arm_smccc_quirk, or NULL when no quirks are required."

Fixed.

> 
> And... should this not be const?  Are we expecting anyone to modify
> the quirk structure?

No, unfortunately.  For qcom, we are stuffing the contents of a6 into the
structure so the caller can get that information.

I'll resend with the documentation fixes.

Regards,

Andy
Russell King (Oracle) Jan. 19, 2017, 3:48 p.m. UTC | #3 
On Thu, Jan 19, 2017 at 09:45:06AM -0600, Andy Gross wrote:
> On Thu, Jan 19, 2017 at 02:40:08PM +0000, Russell King - ARM Linux wrote:
> > On Wed, Jan 11, 2017 at 04:31:57PM -0600, Andy Gross wrote:
> > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> > > index b5abfda..3e28d08 100644
> > > --- a/include/linux/arm-smccc.h
> > > +++ b/include/linux/arm-smccc.h
> > > @@ -72,19 +72,33 @@ struct arm_smccc_res {
> > >  };
> > >  
> > >  /**
> > > - * arm_smccc_smc() - make SMC calls
> > > + * struct arm_smccc_quirk - Contains quirk information
> > > + * id contains quirk identification
> > > + * state contains the quirk specific information
> > 
> > Given that this is a kerneldoc comment, it should really conform to the
> > kerneldoc requirements - see Documentation/kernel-doc-nano-HOWTO.txt:
> > 
> > /**
> >  * struct arm_smccc_quirk - Contains quirk information
> >  * @id: quirk identification
> >  * @state: the quirk specific information
> 
> Ah, I flubbed that.  I'll fix this.
> 
> > 
> > > + */
> > > +struct arm_smccc_quirk {
> > > +	int	id;
> > > +	union {
> > > +		unsigned long a6;
> > > +	} state;
> > > +};
> > > +
> > > +/**
> > > + * __arm_smccc_smc() - make SMC calls
> > >   * @a0-a7: arguments passed in registers 0 to 7
> > >   * @res: result values from registers 0 to 3
> > > + * @quirk: optional quirk structure
> > >   *
> > >   * This function is used to make SMC calls following SMC Calling Convention.
> > >   * The content of the supplied param are copied to registers 0 to 7 prior
> > >   * to the SMC instruction. The return values are updated with the content
> > > - * from register 0 to 3 on return from the SMC instruction.
> > > + * from register 0 to 3 on return from the SMC instruction.  An optional
> > > + * quirk structure provides vendor specific behavior.
> > 
> > It's quite odd to have the result buried in the middle of arguments
> > passed to a function, but I guess for the sake of simplicity in the
> > assembly code that's what we need.
> > 
> > Also:
> > 
> > "@quirk points to an arm_smccc_quirk, or NULL when no quirks are required."
> 
> Fixed.
> 
> > 
> > And... should this not be const?  Are we expecting anyone to modify
> > the quirk structure?
> 
> No, unfortunately.  For qcom, we are stuffing the contents of a6 into the
> structure so the caller can get that information.

Please add that detail to the kerneldoc comments for the structure
concerning state.a6.  It's important that such information is not
lost in the depths of history.

Thanks.
Andy Gross Jan. 19, 2017, 4:16 p.m. UTC | #4 
On Thu, Jan 19, 2017 at 03:48:18PM +0000, Russell King - ARM Linux wrote:
> On Thu, Jan 19, 2017 at 09:45:06AM -0600, Andy Gross wrote:
> > On Thu, Jan 19, 2017 at 02:40:08PM +0000, Russell King - ARM Linux wrote:
> > > On Wed, Jan 11, 2017 at 04:31:57PM -0600, Andy Gross wrote:
> > > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> > > > index b5abfda..3e28d08 100644
> > > > --- a/include/linux/arm-smccc.h
> > > > +++ b/include/linux/arm-smccc.h
> > > > @@ -72,19 +72,33 @@ struct arm_smccc_res {
> > > >  };
> > > >  
> > > >  /**
> > > > - * arm_smccc_smc() - make SMC calls
> > > > + * struct arm_smccc_quirk - Contains quirk information
> > > > + * id contains quirk identification
> > > > + * state contains the quirk specific information
> > > 
> > > Given that this is a kerneldoc comment, it should really conform to the
> > > kerneldoc requirements - see Documentation/kernel-doc-nano-HOWTO.txt:
> > > 
> > > /**
> > >  * struct arm_smccc_quirk - Contains quirk information
> > >  * @id: quirk identification
> > >  * @state: the quirk specific information
> > 
> > Ah, I flubbed that.  I'll fix this.
> > 
> > > 
> > > > + */
> > > > +struct arm_smccc_quirk {
> > > > +	int	id;
> > > > +	union {
> > > > +		unsigned long a6;
> > > > +	} state;
> > > > +};
> > > > +
> > > > +/**
> > > > + * __arm_smccc_smc() - make SMC calls
> > > >   * @a0-a7: arguments passed in registers 0 to 7
> > > >   * @res: result values from registers 0 to 3
> > > > + * @quirk: optional quirk structure
> > > >   *
> > > >   * This function is used to make SMC calls following SMC Calling Convention.
> > > >   * The content of the supplied param are copied to registers 0 to 7 prior
> > > >   * to the SMC instruction. The return values are updated with the content
> > > > - * from register 0 to 3 on return from the SMC instruction.
> > > > + * from register 0 to 3 on return from the SMC instruction.  An optional
> > > > + * quirk structure provides vendor specific behavior.
> > > 
> > > It's quite odd to have the result buried in the middle of arguments
> > > passed to a function, but I guess for the sake of simplicity in the
> > > assembly code that's what we need.
> > > 
> > > Also:
> > > 
> > > "@quirk points to an arm_smccc_quirk, or NULL when no quirks are required."
> > 
> > Fixed.
> > 
> > > 
> > > And... should this not be const?  Are we expecting anyone to modify
> > > the quirk structure?
> > 
> > No, unfortunately.  For qcom, we are stuffing the contents of a6 into the
> > structure so the caller can get that information.
> 
> Please add that detail to the kerneldoc comments for the structure
> concerning state.a6.  It's important that such information is not
> lost in the depths of history.

For documentation, should I split out the union separately?  I don't see any
good examples for documenting union members in unions defined inside structures.

Regards,
Andy
Russell King (Oracle) Jan. 19, 2017, 4:24 p.m. UTC | #5 
On Thu, Jan 19, 2017 at 10:16:58AM -0600, Andy Gross wrote:
> On Thu, Jan 19, 2017 at 03:48:18PM +0000, Russell King - ARM Linux wrote:
> > Please add that detail to the kerneldoc comments for the structure
> > concerning state.a6.  It's important that such information is not
> > lost in the depths of history.
> 
> For documentation, should I split out the union separately?  I don't see any
> good examples for documenting union members in unions defined inside structures.

Good question - I don't know.

 @state.a6: blah

would seem to be a logical and unambiguous way to document it, but I
don't know whether kerneldoc will accept that.
diff mbox

Patch

diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c
index 7e45f69..c2a8e79 100644
--- a/arch/arm/kernel/armksyms.c
+++ b/arch/arm/kernel/armksyms.c
@@ -178,6 +178,6 @@ 
 #endif
 
 #ifdef CONFIG_HAVE_ARM_SMCCC
-EXPORT_SYMBOL(arm_smccc_smc);
+EXPORT_SYMBOL(__arm_smccc_smc);
 EXPORT_SYMBOL(arm_smccc_hvc);
 #endif
diff --git a/arch/arm/kernel/smccc-call.S b/arch/arm/kernel/smccc-call.S
index 2e48b67..eb666d7 100644
--- a/arch/arm/kernel/smccc-call.S
+++ b/arch/arm/kernel/smccc-call.S
@@ -46,11 +46,12 @@  UNWIND(	.fnend)
 /*
  * void smccc_smc(unsigned long a0, unsigned long a1, unsigned long a2,
  *		  unsigned long a3, unsigned long a4, unsigned long a5,
- *		  unsigned long a6, unsigned long a7, struct arm_smccc_res *res)
+ *		  unsigned long a6, unsigned long a7, struct arm_smccc_res *res,
+ *		  struct arm_smccc_quirk *quirk)
  */
-ENTRY(arm_smccc_smc)
+ENTRY(__arm_smccc_smc)
 	SMCCC SMCCC_SMC
-ENDPROC(arm_smccc_smc)
+ENDPROC(__arm_smccc_smc)
 
 /*
  * void smccc_hvc(unsigned long a0, unsigned long a1, unsigned long a2,
diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c
index 78f3680..43370a0 100644
--- a/arch/arm64/kernel/arm64ksyms.c
+++ b/arch/arm64/kernel/arm64ksyms.c
@@ -73,5 +73,5 @@ 
 #endif
 
 	/* arm-smccc */
-EXPORT_SYMBOL(arm_smccc_smc);
+EXPORT_SYMBOL(__arm_smccc_smc);
 EXPORT_SYMBOL(arm_smccc_hvc);
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index bc049af..b3bb7ef 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -143,8 +143,11 @@  int main(void)
   DEFINE(SLEEP_STACK_DATA_SYSTEM_REGS,	offsetof(struct sleep_stack_data, system_regs));
   DEFINE(SLEEP_STACK_DATA_CALLEE_REGS,	offsetof(struct sleep_stack_data, callee_saved_regs));
 #endif
-  DEFINE(ARM_SMCCC_RES_X0_OFFS,	offsetof(struct arm_smccc_res, a0));
-  DEFINE(ARM_SMCCC_RES_X2_OFFS,	offsetof(struct arm_smccc_res, a2));
+  DEFINE(ARM_SMCCC_RES_X0_OFFS,		offsetof(struct arm_smccc_res, a0));
+  DEFINE(ARM_SMCCC_RES_X2_OFFS,		offsetof(struct arm_smccc_res, a2));
+  DEFINE(ARM_SMCCC_QUIRK_ID_OFFS,	offsetof(struct arm_smccc_quirk, id));
+  DEFINE(ARM_SMCCC_QUIRK_STATE_OFFS,	offsetof(struct arm_smccc_quirk, state));
+
   BLANK();
   DEFINE(HIBERN_PBE_ORIG,	offsetof(struct pbe, orig_address));
   DEFINE(HIBERN_PBE_ADDR,	offsetof(struct pbe, address));
diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
index ae0496f..6290696 100644
--- a/arch/arm64/kernel/smccc-call.S
+++ b/arch/arm64/kernel/smccc-call.S
@@ -27,11 +27,12 @@ 
 /*
  * void arm_smccc_smc(unsigned long a0, unsigned long a1, unsigned long a2,
  *		  unsigned long a3, unsigned long a4, unsigned long a5,
- *		  unsigned long a6, unsigned long a7, struct arm_smccc_res *res)
+ *		  unsigned long a6, unsigned long a7, struct arm_smccc_res *res,
+ *		  struct arm_smccc_quirk *quirk)
  */
-ENTRY(arm_smccc_smc)
+ENTRY(__arm_smccc_smc)
 	SMCCC	smc
-ENDPROC(arm_smccc_smc)
+ENDPROC(__arm_smccc_smc)
 
 /*
  * void arm_smccc_hvc(unsigned long a0, unsigned long a1, unsigned long a2,
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index b5abfda..3e28d08 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -72,19 +72,33 @@  struct arm_smccc_res {
 };
 
 /**
- * arm_smccc_smc() - make SMC calls
+ * struct arm_smccc_quirk - Contains quirk information
+ * id contains quirk identification
+ * state contains the quirk specific information
+ */
+struct arm_smccc_quirk {
+	int	id;
+	union {
+		unsigned long a6;
+	} state;
+};
+
+/**
+ * __arm_smccc_smc() - make SMC calls
  * @a0-a7: arguments passed in registers 0 to 7
  * @res: result values from registers 0 to 3
+ * @quirk: optional quirk structure
  *
  * This function is used to make SMC calls following SMC Calling Convention.
  * The content of the supplied param are copied to registers 0 to 7 prior
  * to the SMC instruction. The return values are updated with the content
- * from register 0 to 3 on return from the SMC instruction.
+ * from register 0 to 3 on return from the SMC instruction.  An optional
+ * quirk structure provides vendor specific behavior.
  */
-asmlinkage void arm_smccc_smc(unsigned long a0, unsigned long a1,
+asmlinkage void __arm_smccc_smc(unsigned long a0, unsigned long a1,
 			unsigned long a2, unsigned long a3, unsigned long a4,
 			unsigned long a5, unsigned long a6, unsigned long a7,
-			struct arm_smccc_res *res);
+			struct arm_smccc_res *res, struct arm_smccc_quirk *quirk);
 
 /**
  * arm_smccc_hvc() - make HVC calls
@@ -101,4 +115,8 @@  asmlinkage void arm_smccc_hvc(unsigned long a0, unsigned long a1,
 			unsigned long a5, unsigned long a6, unsigned long a7,
 			struct arm_smccc_res *res);
 
+#define arm_smccc_smc(...) __arm_smccc_smc(__VA_ARGS__, NULL)
+
+#define arm_smccc_smc_quirk(...) __arm_smccc_smc(__VA_ARGS__)
+
 #endif /*__LINUX_ARM_SMCCC_H*/