linux-kernel - [PATCH v2 1/8] powerpc/watchpoint: Fix 512 byte boundary limit

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Date:   Thu,  4 Jun 2020 09:04:36 +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, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/8] powerpc/watchpoint: Fix 512 byte boundary limit

Milton reported that we are aligning start and end address to wrong
size SZ_512M. It should be SZ_512. Fix that.

While doing this change I also found a case where ALIGN() comparison
fails. Within a given aligned range, ALIGN() of two addresses does not
match when start address is pointing to the first byte and end address
is pointing to any other byte except the first one. But that's not true
for ALIGN_DOWN(). ALIGN_DOWN() of any two addresses within that range
will always point to the first byte. So use ALIGN_DOWN() instead of
ALIGN().

Fixes: e68ef121c1f4 ("powerpc/watchpoint: Use builtin ALIGN*() macros")
Reported-by: Milton Miller <miltonm@...ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
---
 arch/powerpc/kernel/hw_breakpoint.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 0000daf0e1da..031e6defc08e 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -419,7 +419,7 @@ static int hw_breakpoint_validate_len(struct arch_hw_breakpoint *hw)
 	if (dawr_enabled()) {
 		max_len = DAWR_MAX_LEN;
 		/* DAWR region can't cross 512 bytes boundary */
-		if (ALIGN(start_addr, SZ_512M) != ALIGN(end_addr - 1, SZ_512M))
+		if (ALIGN_DOWN(start_addr, SZ_512) != ALIGN_DOWN(end_addr - 1, SZ_512))
 			return -EINVAL;
 	} else if (IS_ENABLED(CONFIG_PPC_8xx)) {
 		/* 8xx can setup a range without limitation */
-- 
2.26.2