linux-kernel - [PATCH 5.8 295/464] powerpc/watchpoint: Fix DAWR exception for CACHEOP

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Date:   Mon, 17 Aug 2020 17:14:08 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.8 295/464] powerpc/watchpoint: Fix DAWR exception for CACHEOP

From: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>

[ Upstream commit f3c832f1350bcf1e6906113ee3168066f4235dbe ]

'ea' returned by analyse_instr() needs to be aligned down to cache
block size for CACHEOP instructions. analyse_instr() does not set
size for CACHEOP, thus size also needs to be calculated manually.

Fixes: 27985b2a640e ("powerpc/watchpoint: Don't ignore extraneous exceptions blindly")
Fixes: 74c6881019b7 ("powerpc/watchpoint: Prepare handler to handle more than one watchpoint")
Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/20200723090813.303838-4-ravi.bangoria@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/kernel/hw_breakpoint.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index a971e22aea819..c55e67bab2710 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -538,7 +538,12 @@ static bool check_dawrx_constraints(struct pt_regs *regs, int type,
 	if (OP_IS_LOAD(type) && !(info->type & HW_BRK_TYPE_READ))
 		return false;
 
-	if (OP_IS_STORE(type) && !(info->type & HW_BRK_TYPE_WRITE))
+	/*
+	 * The Cache Management instructions other than dcbz never
+	 * cause a match. i.e. if type is CACHEOP, the instruction
+	 * is dcbz, and dcbz is treated as Store.
+	 */
+	if ((OP_IS_STORE(type) || type == CACHEOP) && !(info->type & HW_BRK_TYPE_WRITE))
 		return false;
 
 	if (is_kernel_addr(regs->nip) && !(info->type & HW_BRK_TYPE_KERNEL))
@@ -601,6 +606,15 @@ static bool check_constraints(struct pt_regs *regs, struct ppc_inst instr,
 	return false;
 }
 
+static int cache_op_size(void)
+{
+#ifdef __powerpc64__
+	return ppc64_caches.l1d.block_size;
+#else
+	return L1_CACHE_BYTES;
+#endif
+}
+
 static void get_instr_detail(struct pt_regs *regs, struct ppc_inst *instr,
 			     int *type, int *size, unsigned long *ea)
 {
@@ -616,7 +630,12 @@ static void get_instr_detail(struct pt_regs *regs, struct ppc_inst *instr,
 	if (!(regs->msr & MSR_64BIT))
 		*ea &= 0xffffffffUL;
 #endif
+
 	*size = GETSIZE(op.type);
+	if (*type == CACHEOP) {
+		*size = cache_op_size();
+		*ea &= ~(*size - 1);
+	}
 }
 
 static bool is_larx_stcx_instr(int type)
-- 
2.25.1