linux-kernel - [PATCH 2/5] Powerpc/hw-breakpoint: Refactor hw_breakpoint_arch

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Date:   Tue, 18 Jun 2019 09:57:29 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     mpe@...erman.id.au
Cc:     benh@...nel.crashing.org, paulus@...ba.org, mikey@...ling.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        npiggin@...il.com, christophe.leroy@....fr,
        naveen.n.rao@...ux.vnet.ibm.com,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: [PATCH 2/5] Powerpc/hw-breakpoint: Refactor hw_breakpoint_arch_parse()

Move feature availability check at the start of the function.
Rearrange comment to it's associated code. Use hw->address and
hw->len in the 512 bytes boundary check(to write if statement
in a single line). Add spacing between code blocks.

Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
---
 arch/powerpc/kernel/hw_breakpoint.c | 34 +++++++++++++++--------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 1908e4fcc132..36bcf705df65 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -133,10 +133,13 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 			     const struct perf_event_attr *attr,
 			     struct arch_hw_breakpoint *hw)
 {
-	int ret = -EINVAL, length_max;
+	int length_max;
+
+	if (!ppc_breakpoint_available())
+		return -ENODEV;
 
 	if (!bp)
-		return ret;
+		return -EINVAL;
 
 	hw->type = HW_BRK_TYPE_TRANSLATE;
 	if (attr->bp_type & HW_BREAKPOINT_R)
@@ -145,34 +148,33 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 		hw->type |= HW_BRK_TYPE_WRITE;
 	if (hw->type == HW_BRK_TYPE_TRANSLATE)
 		/* must set alteast read or write */
-		return ret;
+		return -EINVAL;
+
 	if (!attr->exclude_user)
 		hw->type |= HW_BRK_TYPE_USER;
 	if (!attr->exclude_kernel)
 		hw->type |= HW_BRK_TYPE_KERNEL;
 	if (!attr->exclude_hv)
 		hw->type |= HW_BRK_TYPE_HYP;
+
 	hw->address = attr->bp_addr;
 	hw->len = attr->bp_len;
 
-	/*
-	 * Since breakpoint length can be a maximum of HW_BREAKPOINT_LEN(8)
-	 * and breakpoint addresses are aligned to nearest double-word
-	 * HW_BREAKPOINT_ALIGN by rounding off to the lower address, the
-	 * 'symbolsize' should satisfy the check below.
-	 */
-	if (!ppc_breakpoint_available())
-		return -ENODEV;
 	length_max = 8; /* DABR */
 	if (dawr_enabled()) {
 		length_max = 512 ; /* 64 doublewords */
-		/* DAWR region can't cross 512 boundary */
-		if ((attr->bp_addr >> 9) !=
-		    ((attr->bp_addr + attr->bp_len - 1) >> 9))
+		/* DAWR region can't cross 512 bytes boundary */
+		if ((hw->address >> 9) != ((hw->address + hw->len - 1) >> 9))
 			return -EINVAL;
 	}
-	if (hw->len >
-	    (length_max - (hw->address & HW_BREAKPOINT_ALIGN)))
+
+	/*
+	 * Since breakpoint length can be a maximum of length_max and
+	 * breakpoint addresses are aligned to nearest double-word
+	 * HW_BREAKPOINT_ALIGN by rounding off to the lower address,
+	 * the 'symbolsize' should satisfy the check below.
+	 */
+	if (hw->len > (length_max - (hw->address & HW_BREAKPOINT_ALIGN)))
 		return -EINVAL;
 	return 0;
 }
-- 
2.20.1