[PATCH 1/2] powerpc/ptrace: Fix enforcement of DAWR contraints

From: Michael Neuling <mikey@neuling.org>
To: mpe@ellerman.id.au
Cc: linuxppc-dev@lists.ozlabs.org,
	Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com>,
	Pedro Franco de Carvalho <pedromfc@linux.vnet.ibm.com>,
	Ulrich Weigand <Ulrich.Weigand@de.ibm.com>,
	mikey@neuling.org
Subject: [PATCH 1/2] powerpc/ptrace: Fix enforcement of DAWR contraints
Date: Thu, 17 May 2018 15:37:14 +1000	[thread overview]
Message-ID: <20180517053715.24011-1-mikey@neuling.org> (raw)

Back when we first introduced the DAWR in this commit:
  4ae7ebe952 powerpc: Change hardware breakpoint to allow longer ranges

We screwed up the constraint making it a 1024 byte boundary rather
than a 512. This makes the check overly permissive. Fortunately GDB is
the only real user and it always did they right thing, so we never
noticed.

This fixes the constraint to 512 bytes.

Signed-off-by: Michael Neuling <mikey@neuling.org>
cc: <stable@vger.kernel.org> # v3.9+
---
 arch/powerpc/kernel/hw_breakpoint.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 4c1012b80d..80547dad37 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -178,8 +178,8 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 	if (cpu_has_feature(CPU_FTR_DAWR)) {
 		length_max = 512 ; /* 64 doublewords */
 		/* DAWR region can't cross 512 boundary */
-		if ((bp->attr.bp_addr >> 10) != 
-		    ((bp->attr.bp_addr + bp->attr.bp_len - 1) >> 10))
+		if ((bp->attr.bp_addr >> 9) !=
+		    ((bp->attr.bp_addr + bp->attr.bp_len - 1) >> 9))
 			return -EINVAL;
 	}
 	if (info->len >
-- 
2.14.1
