linux-kernel - [PATCH v4 03/10] powerpc/watchpoint: Fix DAWR exception for CACHEOP

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Message-Id: <20200717040958.70561-4-ravi.bangoria@linux.ibm.com>
Date:   Fri, 17 Jul 2020 09:39:51 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     mpe@...erman.id.au, mikey@...ling.org
Cc:     ravi.bangoria@...ux.ibm.com, apopple@...ux.ibm.com,
        paulus@...ba.org, npiggin@...il.com, christophe.leroy@....fr,
        naveen.n.rao@...ux.vnet.ibm.com, peterz@...radead.org,
        jolsa@...nel.org, oleg@...hat.com, fweisbec@...il.com,
        mingo@...nel.org, pedromfc@...ibm.com, miltonm@...ibm.com,
        jniethe5@...il.com, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 03/10] powerpc/watchpoint: Fix DAWR exception for CACHEOP

'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>
---
 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 a971e22aea81..c55e67bab271 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)
-- 
2.26.2