Re: [PATCH v2 01/21] arm64: Add macros to read/write system registers

[Christoffer Dall]

On Fri, Nov 27, 2015 at 06:49:55PM +, Marc Zyngier wrote:
> From: Mark Rutland 
> 
> Rather than crafting custom macros for reading/writing each system
> register provide generics accessors, read_sysreg and write_sysreg, for
> this purpose.
> 
> Unlike read_cpuid, calls to read_exception_reg are never expected
> to be optimized away or replaced with synthetic values.

how does this comment about read_exception_reg relate to this patch?

> 
> Signed-off-by: Mark Rutland 
> Cc: Catalin Marinas 
> Cc: Marc Zyngier 
> Cc: Suzuki Poulose 
> Cc: Will Deacon 
> Signed-off-by: Marc Zyngier 
> ---
>  arch/arm64/include/asm/sysreg.h | 17 +
>  1 file changed, 17 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index d48ab5b..c9c283a 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -20,6 +20,8 @@
>  #ifndef __ASM_SYSREG_H
>  #define __ASM_SYSREG_H
>  
> +#include 
> +
>  #include 
>  
>  /*
> @@ -208,6 +210,8 @@
>  
>  #else
>  
> +#include 
> +
>  asm(
>  ".irp
> num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n"
>  ".equ__reg_num_x\\num, \\num\n"
> @@ -232,6 +236,19 @@ static inline void config_sctlr_el1(u32 clear, u32 set)
>   val |= set;
>   asm volatile("msr sctlr_el1, %0" : : "r" (val));
>  }
> +
> +#define read_sysreg(r) ({\
> + u64 __val;  \
> + asm volatile("mrs %0, " __stringify(r) : "=r" (__val)); \
> + __val;  \
> +})
> +
> +#define write_sysreg(v, r) do {  \
> + u64 __val = (u64)v; \
> + asm volatile("msr " __stringify(r) ", %0"   \
> +  : : "r" (__val));  \
> +} while (0)
> +
>  #endif
>  
>  #endif   /* __ASM_SYSREG_H */
> -- 
> 2.1.4
> 
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[PATCH v2 01/21] arm64: Add macros to read/write system registers

[Marc Zyngier]

From: Mark Rutland 

Rather than crafting custom macros for reading/writing each system
register provide generics accessors, read_sysreg and write_sysreg, for
this purpose.

Unlike read_cpuid, calls to read_exception_reg are never expected
to be optimized away or replaced with synthetic values.

Signed-off-by: Mark Rutland 
Cc: Catalin Marinas 
Cc: Marc Zyngier 
Cc: Suzuki Poulose 
Cc: Will Deacon 
Signed-off-by: Marc Zyngier 
---
 arch/arm64/include/asm/sysreg.h | 17 +
 1 file changed, 17 insertions(+)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index d48ab5b..c9c283a 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -20,6 +20,8 @@
 #ifndef __ASM_SYSREG_H
 #define __ASM_SYSREG_H
 
+#include 
+
 #include 
 
 /*
@@ -208,6 +210,8 @@
 
 #else
 
+#include 
+
 asm(
 "  .irp
num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n"
 "  .equ__reg_num_x\\num, \\num\n"
@@ -232,6 +236,19 @@ static inline void config_sctlr_el1(u32 clear, u32 set)
val |= set;
asm volatile("msr sctlr_el1, %0" : : "r" (val));
 }
+
+#define read_sysreg(r) ({  \
+   u64 __val;  \
+   asm volatile("mrs %0, " __stringify(r) : "=r" (__val)); \
+   __val;  \
+})
+
+#define write_sysreg(v, r) do {\
+   u64 __val = (u64)v; \
+   asm volatile("msr " __stringify(r) ", %0"   \
+: : "r" (__val));  \
+} while (0)
+
 #endif
 
 #endif /* __ASM_SYSREG_H */
-- 
2.1.4

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