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From: WANG Xuerui <git@xen0n.name>
To: linux-mips@vger.kernel.org
Cc: WANG Xuerui <git@xen0n.name>, Huacai Chen <chenhc@lemote.com>,
	Paul Burton <paulburton@kernel.org>
Subject: [PATCH v4 1/3] MIPS: only register FTLBPar exception handler for supported models
Date: Tue, 28 Jul 2020 18:06:53 +0800
Message-ID: <20200728100655.3005831-2-git@xen0n.name> (raw)
In-Reply-To: <20200728100655.3005831-1-git@xen0n.name>

Previously ExcCode 16 is unconditionally treated as the FTLB parity
exception (FTLBPar), but in fact its semantic is implementation-
dependent. Looking at various manuals it seems the FTLBPar exception is
only present on some recent MIPS Technologies cores, so only register
the handler on these.

Fixes: 75b5b5e0a262790f ("MIPS: Add support for FTLBs")
Reviewed-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: WANG Xuerui <git@xen0n.name>
Cc: Paul Burton <paulburton@kernel.org>
---
 arch/mips/include/asm/cpu-features.h |  4 ++++
 arch/mips/include/asm/cpu.h          |  1 +
 arch/mips/kernel/cpu-probe.c         | 13 +++++++++++++
 arch/mips/kernel/traps.c             |  3 ++-
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index 724dfddcab92..0b1bc7ed913b 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -568,6 +568,10 @@
 # define cpu_has_mac2008_only	__opt(MIPS_CPU_MAC_2008_ONLY)
 #endif
 
+#ifndef cpu_has_ftlbparex
+# define cpu_has_ftlbparex	__opt(MIPS_CPU_FTLBPAREX)
+#endif
+
 #ifdef CONFIG_SMP
 /*
  * Some systems share FTLB RAMs between threads within a core (siblings in
diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h
index f5b04e8f6061..9d08bd33b11f 100644
--- a/arch/mips/include/asm/cpu.h
+++ b/arch/mips/include/asm/cpu.h
@@ -427,6 +427,7 @@ enum cpu_type_enum {
 #define MIPS_CPU_MM_SYSAD	BIT_ULL(58)	/* CPU supports write-through SysAD Valid merge */
 #define MIPS_CPU_MM_FULL	BIT_ULL(59)	/* CPU supports write-through full merge */
 #define MIPS_CPU_MAC_2008_ONLY	BIT_ULL(60)	/* CPU Only support MAC2008 Fused multiply-add instruction */
+#define MIPS_CPU_FTLBPAREX	BIT_ULL(61)	/* CPU has FTLB parity exception */
 
 /*
  * CPU ASE encodings
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index d9e8d39a7289..519d101fd009 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -1827,6 +1827,19 @@ static inline void cpu_probe_mips(struct cpuinfo_mips *c, unsigned int cpu)
 	default:
 		break;
 	}
+
+	/* Recent MIPS cores use the implementation-dependent ExcCode 16 for
+	 * cache/FTLB parity exceptions.
+	 */
+	switch (__get_cpu_type(c->cputype)) {
+	case CPU_PROAPTIV:
+	case CPU_P5600:
+	case CPU_P6600:
+	case CPU_I6400:
+	case CPU_I6500:
+		c->options |= MIPS_CPU_FTLBPAREX;
+		break;
+	}
 }
 
 static inline void cpu_probe_alchemy(struct cpuinfo_mips *c, unsigned int cpu)
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 06aba49d37c9..9c37a6997259 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -2454,7 +2454,8 @@ void __init trap_init(void)
 	if (cpu_has_fpu && !cpu_has_nofpuex)
 		set_except_vector(EXCCODE_FPE, handle_fpe);
 
-	set_except_vector(MIPS_EXCCODE_TLBPAR, handle_ftlb);
+	if (cpu_has_ftlbparex)
+		set_except_vector(MIPS_EXCCODE_TLBPAR, handle_ftlb);
 
 	if (cpu_has_rixiex) {
 		set_except_vector(EXCCODE_TLBRI, tlb_do_page_fault_0);
-- 
2.25.1


  reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-28 10:06 [PATCH v4 0/3] Refactor FTLBPar exception handling and add GSExc handler WANG Xuerui
2020-07-28 10:06 ` WANG Xuerui [this message]
2020-07-28 10:06 ` [PATCH v4 2/3] MIPS: add definitions for Loongson-specific CP0.Diag1 register WANG Xuerui
2020-07-28 10:06 ` [PATCH v4 3/3] MIPS: handle Loongson-specific GSExc exception WANG Xuerui
2020-07-28 20:51   ` Thomas Bogendoerfer
2020-07-29 12:21     ` WANG Xuerui

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