[PATCHv2 1/3] powerpc: lib: sstep: fix 'sthcx' instruction

[PATCHv2 1/3] powerpc: lib: sstep: fix 'sthcx' instruction

[Anders Roxell]

Looks like there been a copy paste mistake when added the instruction
'stbcx' twice and one was probably meant to be 'sthcx'.
Changing to 'sthcx' from 'stbcx'.

Cc: <stable@vger.kernel.org> # v4.13+
Fixes: 350779a29f11 ("powerpc: Handle most loads and stores in instruction emulation code")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/powerpc/lib/sstep.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index bd3734d5be89..d2d29243fa6d 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -3389,7 +3389,7 @@ int emulate_loadstore(struct pt_regs *regs, struct instruction_op *op)
 			__put_user_asmx(op->val, ea, err, "stbcx.", cr);
 			break;
 		case 2:
-			__put_user_asmx(op->val, ea, err, "stbcx.", cr);
+			__put_user_asmx(op->val, ea, err, "sthcx.", cr);
 			break;
 #endif
 		case 4:
-- 
2.34.1

[PATCHv2 1/3] powerpc: lib: sstep: fix 'sthcx' instruction

[Anders Roxell]

Looks like there been a copy paste mistake when added the instruction
'stbcx' twice and one was probably meant to be 'sthcx'.
Changing to 'sthcx' from 'stbcx'.

Cc: <stable@vger.kernel.org> # v4.13+
Fixes: 350779a29f11 ("powerpc: Handle most loads and stores in instruction emulation code")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/powerpc/lib/sstep.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index bd3734d5be89..d2d29243fa6d 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -3389,7 +3389,7 @@ int emulate_loadstore(struct pt_regs *regs, struct instruction_op *op)
 			__put_user_asmx(op->val, ea, err, "stbcx.", cr);
 			break;
 		case 2:
-			__put_user_asmx(op->val, ea, err, "stbcx.", cr);
+			__put_user_asmx(op->val, ea, err, "sthcx.", cr);
 			break;
 #endif
 		case 4:
-- 
2.34.1

[PATCHv2 2/3] powerpc: fix build errors

[Anders Roxell]

Building tinyconfig with gcc (Debian 11.2.0-16) and assembler (Debian
2.37.90.20220207) the following build error shows up:

 {standard input}: Assembler messages:
 {standard input}:1190: Error: unrecognized opcode: `stbcix'
 {standard input}:1433: Error: unrecognized opcode: `lwzcix'
 {standard input}:1453: Error: unrecognized opcode: `stbcix'
 {standard input}:1460: Error: unrecognized opcode: `stwcix'
 {standard input}:1596: Error: unrecognized opcode: `stbcix'
 ...

Rework to add assembler directives [1] around the instruction. Going
through the them one by one shows that the changes should be safe.  Like
__get_user_atomic_128_aligned() is only called in p9_hmi_special_emu(),
which according to the name is specific to power9.  And __raw_rm_read*()
are only called in things that are powernv or book3s_hv specific.

[1] https://sourceware.org/binutils/docs/as/PowerPC_002dPseudo.html#PowerPC_002dPseudo

Cc: <stable@vger.kernel.org>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/powerpc/include/asm/io.h        | 40 ++++++++++++++++++++++------
 arch/powerpc/include/asm/uaccess.h   |  3 +++
 arch/powerpc/platforms/powernv/rng.c |  6 ++++-
 3 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index beba4979bff9..fee979d3a1aa 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -359,25 +359,37 @@ static inline void __raw_writeq_be(unsigned long v, volatile void __iomem *addr)
  */
 static inline void __raw_rm_writeb(u8 val, volatile void __iomem *paddr)
 {
-	__asm__ __volatile__("stbcix %0,0,%1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      stbcix %0,0,%1;  \
+			      .machine pop;"
 		: : "r" (val), "r" (paddr) : "memory");
 }
 
 static inline void __raw_rm_writew(u16 val, volatile void __iomem *paddr)
 {
-	__asm__ __volatile__("sthcix %0,0,%1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      sthcix %0,0,%1;  \
+			      .machine pop;"
 		: : "r" (val), "r" (paddr) : "memory");
 }
 
 static inline void __raw_rm_writel(u32 val, volatile void __iomem *paddr)
 {
-	__asm__ __volatile__("stwcix %0,0,%1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      stwcix %0,0,%1;  \
+			      .machine pop;"
 		: : "r" (val), "r" (paddr) : "memory");
 }
 
 static inline void __raw_rm_writeq(u64 val, volatile void __iomem *paddr)
 {
-	__asm__ __volatile__("stdcix %0,0,%1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      stdcix %0,0,%1;  \
+			      .machine pop;"
 		: : "r" (val), "r" (paddr) : "memory");
 }
 
@@ -389,7 +401,10 @@ static inline void __raw_rm_writeq_be(u64 val, volatile void __iomem *paddr)
 static inline u8 __raw_rm_readb(volatile void __iomem *paddr)
 {
 	u8 ret;
-	__asm__ __volatile__("lbzcix %0,0, %1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      lbzcix %0,0, %1; \
+			      .machine pop;"
 			     : "=r" (ret) : "r" (paddr) : "memory");
 	return ret;
 }
@@ -397,7 +412,10 @@ static inline u8 __raw_rm_readb(volatile void __iomem *paddr)
 static inline u16 __raw_rm_readw(volatile void __iomem *paddr)
 {
 	u16 ret;
-	__asm__ __volatile__("lhzcix %0,0, %1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      lhzcix %0,0, %1; \
+			      .machine pop;"
 			     : "=r" (ret) : "r" (paddr) : "memory");
 	return ret;
 }
@@ -405,7 +423,10 @@ static inline u16 __raw_rm_readw(volatile void __iomem *paddr)
 static inline u32 __raw_rm_readl(volatile void __iomem *paddr)
 {
 	u32 ret;
-	__asm__ __volatile__("lwzcix %0,0, %1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      lwzcix %0,0, %1; \
+			      .machine pop;"
 			     : "=r" (ret) : "r" (paddr) : "memory");
 	return ret;
 }
@@ -413,7 +434,10 @@ static inline u32 __raw_rm_readl(volatile void __iomem *paddr)
 static inline u64 __raw_rm_readq(volatile void __iomem *paddr)
 {
 	u64 ret;
-	__asm__ __volatile__("ldcix %0,0, %1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      ldcix %0,0, %1;  \
+			      .machine pop;"
 			     : "=r" (ret) : "r" (paddr) : "memory");
 	return ret;
 }
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 63316100080c..4a35423f766d 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -125,8 +125,11 @@ do {								\
  */
 #define __get_user_atomic_128_aligned(kaddr, uaddr, err)		\
 	__asm__ __volatile__(				\
+		".machine push\n"			\
+		".machine altivec\n"			\
 		"1:	lvx  0,0,%1	# get user\n"	\
 		" 	stvx 0,0,%2	# put kernel\n"	\
+		".machine pop\n"			\
 		"2:\n"					\
 		".section .fixup,\"ax\"\n"		\
 		"3:	li %0,%3\n"			\
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index b4386714494a..e3d44b36ae98 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -43,7 +43,11 @@ static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
 	unsigned long parity;
 
 	/* Calculate the parity of the value */
-	asm ("popcntd %0,%1" : "=r" (parity) : "r" (val));
+	asm (".machine push;   \
+	      .machine power7; \
+	      popcntd %0,%1;   \
+	      .machine pop;"
+	     : "=r" (parity) : "r" (val));
 
 	/* xor our value with the previous mask */
 	val ^= rng->mask;
-- 
2.34.1

[PATCHv2 2/3] powerpc: fix build errors

[Anders Roxell]

Building tinyconfig with gcc (Debian 11.2.0-16) and assembler (Debian
2.37.90.20220207) the following build error shows up:

 {standard input}: Assembler messages:
 {standard input}:1190: Error: unrecognized opcode: `stbcix'
 {standard input}:1433: Error: unrecognized opcode: `lwzcix'
 {standard input}:1453: Error: unrecognized opcode: `stbcix'
 {standard input}:1460: Error: unrecognized opcode: `stwcix'
 {standard input}:1596: Error: unrecognized opcode: `stbcix'
 ...

Rework to add assembler directives [1] around the instruction. Going
through the them one by one shows that the changes should be safe.  Like
__get_user_atomic_128_aligned() is only called in p9_hmi_special_emu(),
which according to the name is specific to power9.  And __raw_rm_read*()
are only called in things that are powernv or book3s_hv specific.

[1] https://sourceware.org/binutils/docs/as/PowerPC_002dPseudo.html#PowerPC_002dPseudo

Cc: <stable@vger.kernel.org>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/powerpc/include/asm/io.h        | 40 ++++++++++++++++++++++------
 arch/powerpc/include/asm/uaccess.h   |  3 +++
 arch/powerpc/platforms/powernv/rng.c |  6 ++++-
 3 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index beba4979bff9..fee979d3a1aa 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -359,25 +359,37 @@ static inline void __raw_writeq_be(unsigned long v, volatile void __iomem *addr)
  */
 static inline void __raw_rm_writeb(u8 val, volatile void __iomem *paddr)
 {
-	__asm__ __volatile__("stbcix %0,0,%1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      stbcix %0,0,%1;  \
+			      .machine pop;"
 		: : "r" (val), "r" (paddr) : "memory");
 }
 
 static inline void __raw_rm_writew(u16 val, volatile void __iomem *paddr)
 {
-	__asm__ __volatile__("sthcix %0,0,%1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      sthcix %0,0,%1;  \
+			      .machine pop;"
 		: : "r" (val), "r" (paddr) : "memory");
 }
 
 static inline void __raw_rm_writel(u32 val, volatile void __iomem *paddr)
 {
-	__asm__ __volatile__("stwcix %0,0,%1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      stwcix %0,0,%1;  \
+			      .machine pop;"
 		: : "r" (val), "r" (paddr) : "memory");
 }
 
 static inline void __raw_rm_writeq(u64 val, volatile void __iomem *paddr)
 {
-	__asm__ __volatile__("stdcix %0,0,%1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      stdcix %0,0,%1;  \
+			      .machine pop;"
 		: : "r" (val), "r" (paddr) : "memory");
 }
 
@@ -389,7 +401,10 @@ static inline void __raw_rm_writeq_be(u64 val, volatile void __iomem *paddr)
 static inline u8 __raw_rm_readb(volatile void __iomem *paddr)
 {
 	u8 ret;
-	__asm__ __volatile__("lbzcix %0,0, %1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      lbzcix %0,0, %1; \
+			      .machine pop;"
 			     : "=r" (ret) : "r" (paddr) : "memory");
 	return ret;
 }
@@ -397,7 +412,10 @@ static inline u8 __raw_rm_readb(volatile void __iomem *paddr)
 static inline u16 __raw_rm_readw(volatile void __iomem *paddr)
 {
 	u16 ret;
-	__asm__ __volatile__("lhzcix %0,0, %1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      lhzcix %0,0, %1; \
+			      .machine pop;"
 			     : "=r" (ret) : "r" (paddr) : "memory");
 	return ret;
 }
@@ -405,7 +423,10 @@ static inline u16 __raw_rm_readw(volatile void __iomem *paddr)
 static inline u32 __raw_rm_readl(volatile void __iomem *paddr)
 {
 	u32 ret;
-	__asm__ __volatile__("lwzcix %0,0, %1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      lwzcix %0,0, %1; \
+			      .machine pop;"
 			     : "=r" (ret) : "r" (paddr) : "memory");
 	return ret;
 }
@@ -413,7 +434,10 @@ static inline u32 __raw_rm_readl(volatile void __iomem *paddr)
 static inline u64 __raw_rm_readq(volatile void __iomem *paddr)
 {
 	u64 ret;
-	__asm__ __volatile__("ldcix %0,0, %1"
+	__asm__ __volatile__(".machine push;   \
+			      .machine power6; \
+			      ldcix %0,0, %1;  \
+			      .machine pop;"
 			     : "=r" (ret) : "r" (paddr) : "memory");
 	return ret;
 }
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 63316100080c..4a35423f766d 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -125,8 +125,11 @@ do {								\
  */
 #define __get_user_atomic_128_aligned(kaddr, uaddr, err)		\
 	__asm__ __volatile__(				\
+		".machine push\n"			\
+		".machine altivec\n"			\
 		"1:	lvx  0,0,%1	# get user\n"	\
 		" 	stvx 0,0,%2	# put kernel\n"	\
+		".machine pop\n"			\
 		"2:\n"					\
 		".section .fixup,\"ax\"\n"		\
 		"3:	li %0,%3\n"			\
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index b4386714494a..e3d44b36ae98 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -43,7 +43,11 @@ static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
 	unsigned long parity;
 
 	/* Calculate the parity of the value */
-	asm ("popcntd %0,%1" : "=r" (parity) : "r" (val));
+	asm (".machine push;   \
+	      .machine power7; \
+	      popcntd %0,%1;   \
+	      .machine pop;"
+	     : "=r" (parity) : "r" (val));
 
 	/* xor our value with the previous mask */
 	val ^= rng->mask;
-- 
2.34.1

[PATCHv2 3/3] powerpc: lib: sstep: fix build errors

[Anders Roxell]

Building tinyconfig with gcc (Debian 11.2.0-16) and assembler (Debian
2.37.90.20220207) the following build error shows up:

{standard input}: Assembler messages:
{standard input}:10576: Error: unrecognized opcode: `stbcx.'
{standard input}:10680: Error: unrecognized opcode: `lharx'
{standard input}:10694: Error: unrecognized opcode: `lbarx'

Rework to add assembler directives [1] around the instruction.  The
problem with this might be that we can trick a power6 into
single-stepping through an stbcx. for instance, and it will execute that
in kernel mode.

[1] https://sourceware.org/binutils/docs/as/PowerPC_002dPseudo.html#PowerPC_002dPseudo

Cc: <stable@vger.kernel.org>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/powerpc/lib/sstep.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index d2d29243fa6d..f3ed80513a90 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1097,7 +1097,10 @@ NOKPROBE_SYMBOL(emulate_dcbz);
 
 #define __put_user_asmx(x, addr, err, op, cr)		\
 	__asm__ __volatile__(				\
+		".machine push\n"			\
+		".machine power8\n"			\
 		"1:	" op " %2,0,%3\n"		\
+		".machine pop\n"			\
 		"	mfcr	%1\n"			\
 		"2:\n"					\
 		".section .fixup,\"ax\"\n"		\
@@ -1110,7 +1113,10 @@ NOKPROBE_SYMBOL(emulate_dcbz);
 
 #define __get_user_asmx(x, addr, err, op)		\
 	__asm__ __volatile__(				\
+		".machine push\n"			\
+		".machine power8\n"			\
 		"1:	"op" %1,0,%2\n"			\
+		".machine pop\n"			\
 		"2:\n"					\
 		".section .fixup,\"ax\"\n"		\
 		"3:	li	%0,%3\n"		\
-- 
2.34.1

[PATCHv2 3/3] powerpc: lib: sstep: fix build errors

[Anders Roxell]

Building tinyconfig with gcc (Debian 11.2.0-16) and assembler (Debian
2.37.90.20220207) the following build error shows up:

{standard input}: Assembler messages:
{standard input}:10576: Error: unrecognized opcode: `stbcx.'
{standard input}:10680: Error: unrecognized opcode: `lharx'
{standard input}:10694: Error: unrecognized opcode: `lbarx'

Rework to add assembler directives [1] around the instruction.  The
problem with this might be that we can trick a power6 into
single-stepping through an stbcx. for instance, and it will execute that
in kernel mode.

[1] https://sourceware.org/binutils/docs/as/PowerPC_002dPseudo.html#PowerPC_002dPseudo

Cc: <stable@vger.kernel.org>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/powerpc/lib/sstep.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index d2d29243fa6d..f3ed80513a90 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1097,7 +1097,10 @@ NOKPROBE_SYMBOL(emulate_dcbz);
 
 #define __put_user_asmx(x, addr, err, op, cr)		\
 	__asm__ __volatile__(				\
+		".machine push\n"			\
+		".machine power8\n"			\
 		"1:	" op " %2,0,%3\n"		\
+		".machine pop\n"			\
 		"	mfcr	%1\n"			\
 		"2:\n"					\
 		".section .fixup,\"ax\"\n"		\
@@ -1110,7 +1113,10 @@ NOKPROBE_SYMBOL(emulate_dcbz);
 
 #define __get_user_asmx(x, addr, err, op)		\
 	__asm__ __volatile__(				\
+		".machine push\n"			\
+		".machine power8\n"			\
 		"1:	"op" %1,0,%2\n"			\
+		".machine pop\n"			\
 		"2:\n"					\
 		".section .fixup,\"ax\"\n"		\
 		"3:	li	%0,%3\n"		\
-- 
2.34.1

Re: [PATCHv2 1/3] powerpc: lib: sstep: fix 'sthcx' instruction

[Michael Ellerman]

On Thu, 24 Feb 2022 17:22:13 +0100, Anders Roxell wrote:
> Looks like there been a copy paste mistake when added the instruction
> 'stbcx' twice and one was probably meant to be 'sthcx'.
> Changing to 'sthcx' from 'stbcx'.
> 
> 

Applied to powerpc/next.

[1/3] powerpc: lib: sstep: fix 'sthcx' instruction
      https://git.kernel.org/powerpc/c/a633cb1edddaa643fadc70abc88f89a408fa834a
[2/3] powerpc: fix build errors
      https://git.kernel.org/powerpc/c/8667d0d64dd1f84fd41b5897fd87fa9113ae05e3
[3/3] powerpc: lib: sstep: fix build errors
      https://git.kernel.org/powerpc/c/8219d31effa7be5dbc7ff915d7970672e028c701

cheers

Re: [PATCHv2 1/3] powerpc: lib: sstep: fix 'sthcx' instruction

[Michael Ellerman]

On Thu, 24 Feb 2022 17:22:13 +0100, Anders Roxell wrote:
> Looks like there been a copy paste mistake when added the instruction
> 'stbcx' twice and one was probably meant to be 'sthcx'.
> Changing to 'sthcx' from 'stbcx'.
> 
> 

Applied to powerpc/next.

[1/3] powerpc: lib: sstep: fix 'sthcx' instruction
      https://git.kernel.org/powerpc/c/a633cb1edddaa643fadc70abc88f89a408fa834a
[2/3] powerpc: fix build errors
      https://git.kernel.org/powerpc/c/8667d0d64dd1f84fd41b5897fd87fa9113ae05e3
[3/3] powerpc: lib: sstep: fix build errors
      https://git.kernel.org/powerpc/c/8219d31effa7be5dbc7ff915d7970672e028c701

cheers