[PATCH 1/3] powerpc/32s: Change mfsrin() into a static inline function

[PATCH 1/3] powerpc/32s: Change mfsrin() into a static inline function

[Christophe Leroy]

mfsrin() is a macro.

Change in into an inline function to avoid conflicts in KVM
and make it more evolutive.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/reg.h    | 11 ++++++++---
 arch/powerpc/kvm/book3s_emulate.c |  4 ----
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index d05dca30604d..f0fb03c9f289 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1414,9 +1414,14 @@ static inline void msr_check_and_clear(unsigned long bits)
 }
 
 #ifdef CONFIG_PPC32
-#define mfsrin(v)	({unsigned int rval; \
-			asm volatile("mfsrin %0,%1" : "=r" (rval) : "r" (v)); \
-					rval;})
+static inline u32 mfsrin(u32 idx)
+{
+	u32 val;
+
+	asm volatile("mfsrin %0, %1" : "=r" (val): "r" (idx));
+
+	return val;
+}
 
 static inline void mtsrin(u32 val, u32 idx)
 {
diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index b08cc15f31c7..fdb57be71aa6 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -61,10 +61,6 @@
 #define SPRN_GQR6		918
 #define SPRN_GQR7		919
 
-/* Book3S_32 defines mfsrin(v) - but that messes up our abstract
- * function pointers, so let's just disable the define. */
-#undef mfsrin
-
 enum priv_level {
 	PRIV_PROBLEM = 0,
 	PRIV_SUPER = 1,
-- 
2.25.0

[PATCH 2/3] powerpc/32s: mfsrin()/mtsrin() become mfsr()/mtsr()

[Christophe Leroy]

Function names should tell what the function does, not how.

mfsrin() and mtsrin() are read/writing segment registers.

They are called that way because they are using mfsrin and mtsrin
instructions, but it doesn't matter for the caller.

In preparation of following patch, change their name to mfsr() and mtsr()
in order to make it obvious they manipulate segment registers without
messing up with how they do it.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/book3s/32/kup.h | 8 ++++----
 arch/powerpc/include/asm/reg.h           | 4 ++--
 arch/powerpc/mm/book3s32/mmu.c           | 2 +-
 arch/powerpc/mm/ptdump/segment_regs.c    | 2 +-
 arch/powerpc/xmon/xmon.c                 | 2 +-
 5 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index e8ea6ac809a9..d5e45eedf581 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -95,12 +95,12 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end)
 	addr &= 0xf0000000;	/* align addr to start of segment */
 	barrier();	/* make sure thread.kuap is updated before playing with SRs */
 	while (addr < end) {
-		mtsrin(sr, addr);
+		mtsr(sr, addr);
 		sr += 0x111;		/* next VSID */
 		sr &= 0xf0ffffff;	/* clear VSID overflow */
 		addr += 0x10000000;	/* address of next segment */
 	}
-	isync();	/* Context sync required after mtsrin() */
+	isync();	/* Context sync required after mtsr() */
 }
 
 static __always_inline void allow_user_access(void __user *to, const void __user *from,
@@ -122,7 +122,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user
 	end = min(addr + size, TASK_SIZE);
 
 	current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf);
-	kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end);	/* Clear Ks */
+	kuap_update_sr(mfsr(addr) & ~SR_KS, addr, end);	/* Clear Ks */
 }
 
 static __always_inline void prevent_user_access(void __user *to, const void __user *from,
@@ -151,7 +151,7 @@ static __always_inline void prevent_user_access(void __user *to, const void __us
 	}
 
 	current->thread.kuap = 0;
-	kuap_update_sr(mfsrin(addr) | SR_KS, addr, end);	/* set Ks */
+	kuap_update_sr(mfsr(addr) | SR_KS, addr, end);	/* set Ks */
 }
 
 static inline unsigned long prevent_user_access_return(void)
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index f0fb03c9f289..eeab7e7dc699 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1414,7 +1414,7 @@ static inline void msr_check_and_clear(unsigned long bits)
 }
 
 #ifdef CONFIG_PPC32
-static inline u32 mfsrin(u32 idx)
+static inline u32 mfsr(u32 idx)
 {
 	u32 val;
 
@@ -1423,7 +1423,7 @@ static inline u32 mfsrin(u32 idx)
 	return val;
 }
 
-static inline void mtsrin(u32 val, u32 idx)
+static inline void mtsr(u32 val, u32 idx)
 {
 	asm volatile("mtsrin %0, %1" : : "r" (val), "r" (idx));
 }
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index 859e5bd603ac..d7eb266a3f7a 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -234,7 +234,7 @@ void mmu_mark_initmem_nx(void)
 		if (is_module_segment(i << 28))
 			continue;
 
-		mtsrin(mfsrin(i << 28) | 0x10000000, i << 28);
+		mtsr(mfsr(i << 28) | 0x10000000, i << 28);
 	}
 }
 
diff --git a/arch/powerpc/mm/ptdump/segment_regs.c b/arch/powerpc/mm/ptdump/segment_regs.c
index dde2fe8de4b2..565048a0c9be 100644
--- a/arch/powerpc/mm/ptdump/segment_regs.c
+++ b/arch/powerpc/mm/ptdump/segment_regs.c
@@ -10,7 +10,7 @@
 
 static void seg_show(struct seq_file *m, int i)
 {
-	u32 val = mfsrin(i << 28);
+	u32 val = mfsr(i << 28);
 
 	seq_printf(m, "0x%01x0000000-0x%01xfffffff ", i, i);
 	seq_printf(m, "Kern key %d ", (val >> 30) & 1);
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index cec432eb9189..3fe37495f63d 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -3719,7 +3719,7 @@ void dump_segments(void)
 
 	printf("sr0-15 =");
 	for (i = 0; i < 16; ++i)
-		printf(" %x", mfsrin(i << 28));
+		printf(" %x", mfsr(i << 28));
 	printf("\n");
 }
 #endif
-- 
2.25.0

[PATCH 3/3] powerpc/32s: Allow constant folding in mtsr()/mfsr()

[Christophe Leroy]

On the same way as we did in wrtee(), add an alternative
using mtsr/mfsr instructions instead of mtsrin/mfsrin
when the segment register can be determined at compile time.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/reg.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index eeab7e7dc699..da103e92c112 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1418,14 +1418,20 @@ static inline u32 mfsr(u32 idx)
 {
 	u32 val;
 
-	asm volatile("mfsrin %0, %1" : "=r" (val): "r" (idx));
+	if (__builtin_constant_p(idx))
+		asm volatile("mfsr %0, %1" : "=r" (val): "i" (idx >> 28));
+	else
+		asm volatile("mfsrin %0, %1" : "=r" (val): "r" (idx));
 
 	return val;
 }
 
 static inline void mtsr(u32 val, u32 idx)
 {
-	asm volatile("mtsrin %0, %1" : : "r" (val), "r" (idx));
+	if (__builtin_constant_p(idx))
+		asm volatile("mtsr %1, %0" : : "r" (val), "i" (idx >> 28));
+	else
+		asm volatile("mtsrin %0, %1" : : "r" (val), "r" (idx));
 }
 #endif
 
-- 
2.25.0

Re: [PATCH 1/3] powerpc/32s: Change mfsrin() into a static inline function

[Michael Ellerman]

On Sat, 6 Feb 2021 11:47:26 +0000 (UTC), Christophe Leroy wrote:
> mfsrin() is a macro.
> 
> Change in into an inline function to avoid conflicts in KVM
> and make it more evolutive.

Applied to powerpc/next.

[1/3] powerpc/32s: Change mfsrin() into a static inline function
      https://git.kernel.org/powerpc/c/fd659e8f2c6d1e1e96fd5bdb515518801cd02012
[2/3] powerpc/32s: mfsrin()/mtsrin() become mfsr()/mtsr()
      https://git.kernel.org/powerpc/c/179ae57dbad1b9a83eec376aa44d54fc24352e37
[3/3] powerpc/32s: Allow constant folding in mtsr()/mfsr()
      https://git.kernel.org/powerpc/c/b842d131c7983f8f0b9c9572c073130b5f2bcf11

cheers