linux-kernel - [ 43/79] powerpc/hw_breakpoints: Add DABRX cpu feature to fix 32-bit regression

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Message-Id: <20130611195321.560201431@linuxfoundation.org>
Date:	Tue, 11 Jun 2013 13:03:09 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Michael Neuling <mikey@...ling.org>,
	"Gorelik, Jacob (335F)" <jacob.gorelik@....nasa.gov>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: [ 43/79] powerpc/hw_breakpoints: Add DABRX cpu feature to fix 32-bit regression

3.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Neuling <mikey@...ling.org>

commit 82a9f16adc12f51c3f8ea59a7c3c120241aff836 upstream.

When introducing support for DABRX in 4474ef0, we broke older 32-bit CPUs
that don't have that register.

Some CPUs have a DABR but not DABRX.  Configuration are:
- No 32bit CPUs have DABRX but some have DABR.
- POWER4+ and below have the DABR but no DABRX.
- 970 and POWER5 and above have DABR and DABRX.
- POWER8 has DAWR, hence no DABRX.

This introduces CPU_FTR_DABRX and sets it on appropriate CPUs.  We use
the top 64 bits for CPU FTR bits since only 64 bit CPUs have this.

Processors that don't have the DABRX will still work as they will fall
back to software filtering these breakpoints via perf_exclude_event().

Signed-off-by: Michael Neuling <mikey@...ling.org>
Reported-by: "Gorelik, Jacob (335F)" <jacob.gorelik@....nasa.gov>
Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/include/asm/cputable.h |   17 ++++++++++-------
 arch/powerpc/kernel/process.c       |    3 ++-
 2 files changed, 12 insertions(+), 8 deletions(-)

--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -175,6 +175,7 @@ extern const char *powerpc_base_platform
 #define CPU_FTR_BCTAR			LONG_ASM_CONST(0x0100000000000000)
 #define	CPU_FTR_HAS_PPR			LONG_ASM_CONST(0x0200000000000000)
 #define CPU_FTR_DAWR			LONG_ASM_CONST(0x0400000000000000)
+#define CPU_FTR_DABRX			LONG_ASM_CONST(0x0800000000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -391,19 +392,20 @@ extern const char *powerpc_base_platform
 	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | CPU_FTR_ARCH_201 | \
 	    CPU_FTR_ALTIVEC_COMP | CPU_FTR_CAN_NAP | CPU_FTR_MMCRA | \
 	    CPU_FTR_CP_USE_DCBTZ | CPU_FTR_STCX_CHECKS_ADDRESS | \
-	    CPU_FTR_HVMODE)
+	    CPU_FTR_HVMODE | CPU_FTR_DABRX)
 #define CPU_FTRS_POWER5	(CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
 	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
 	    CPU_FTR_MMCRA | CPU_FTR_SMT | \
 	    CPU_FTR_COHERENT_ICACHE | CPU_FTR_PURR | \
-	    CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB)
+	    CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_DABRX)
 #define CPU_FTRS_POWER6 (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
 	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
 	    CPU_FTR_MMCRA | CPU_FTR_SMT | \
 	    CPU_FTR_COHERENT_ICACHE | \
 	    CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
 	    CPU_FTR_DSCR | CPU_FTR_UNALIGNED_LD_STD | \
-	    CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_CFAR)
+	    CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_CFAR | \
+	    CPU_FTR_DABRX)
 #define CPU_FTRS_POWER7 (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
 	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | CPU_FTR_ARCH_206 |\
 	    CPU_FTR_MMCRA | CPU_FTR_SMT | \
@@ -412,7 +414,7 @@ extern const char *powerpc_base_platform
 	    CPU_FTR_DSCR | CPU_FTR_SAO  | CPU_FTR_ASYM_SMT | \
 	    CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
 	    CPU_FTR_ICSWX | CPU_FTR_CFAR | CPU_FTR_HVMODE | \
-	    CPU_FTR_VMX_COPY | CPU_FTR_HAS_PPR)
+	    CPU_FTR_VMX_COPY | CPU_FTR_HAS_PPR | CPU_FTR_DABRX)
 #define CPU_FTRS_POWER8 (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
 	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | CPU_FTR_ARCH_206 |\
 	    CPU_FTR_MMCRA | CPU_FTR_SMT | \
@@ -427,14 +429,15 @@ extern const char *powerpc_base_platform
 	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
 	    CPU_FTR_ALTIVEC_COMP | CPU_FTR_MMCRA | CPU_FTR_SMT | \
 	    CPU_FTR_PAUSE_ZERO  | CPU_FTR_CELL_TB_BUG | CPU_FTR_CP_USE_DCBTZ | \
-	    CPU_FTR_UNALIGNED_LD_STD)
+	    CPU_FTR_UNALIGNED_LD_STD | CPU_FTR_DABRX)
 #define CPU_FTRS_PA6T (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
 	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_ALTIVEC_COMP | \
-	    CPU_FTR_PURR | CPU_FTR_REAL_LE)
+	    CPU_FTR_PURR | CPU_FTR_REAL_LE | CPU_FTR_DABRX)
 #define CPU_FTRS_COMPATIBLE	(CPU_FTR_USE_TB | CPU_FTR_PPCAS_ARCH_V2)
 
 #define CPU_FTRS_A2 (CPU_FTR_USE_TB | CPU_FTR_SMT | CPU_FTR_DBELL | \
-		     CPU_FTR_NOEXECUTE | CPU_FTR_NODSISRALIGN | CPU_FTR_ICSWX)
+		     CPU_FTR_NOEXECUTE | CPU_FTR_NODSISRALIGN | \
+		     CPU_FTR_ICSWX | CPU_FTR_DABRX )
 
 #ifdef __powerpc64__
 #ifdef CONFIG_PPC_BOOK3E
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -392,7 +392,8 @@ static inline int __set_dabr(unsigned lo
 static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
 {
 	mtspr(SPRN_DABR, dabr);
-	mtspr(SPRN_DABRX, dabrx);
+	if (cpu_has_feature(CPU_FTR_DABRX))
+		mtspr(SPRN_DABRX, dabrx);
 	return 0;
 }
 #else


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