linux-kernel - [PATCH] powerpc/watchpoint: Don't call dar_within

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Message-Id: <20200222082049.330435-1-ravi.bangoria@linux.ibm.com>
Date:   Sat, 22 Feb 2020 13:50:49 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     mpe@...erman.id.au
Cc:     christophe.leroy@....fr, mikey@...ling.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: [PATCH] powerpc/watchpoint: Don't call dar_within_range() for Book3S

DAR is set to the first byte of overlap between actual access and
watched range at DSI on Book3S processor. But actual access range
might or might not be within user asked range. So for Book3S, it
must not call dar_within_range().

This revert portion of commit 39413ae00967 ("powerpc/hw_breakpoints:
Rewrite 8xx breakpoints to allow any address range size.").

Before patch:
  # ./tools/testing/selftests/powerpc/ptrace/perf-hwbreak
  ...
  TESTED: No overlap
  FAILED: Partial overlap: 0 != 2
  TESTED: Partial overlap
  TESTED: No overlap
  FAILED: Full overlap: 0 != 2
  failure: perf_hwbreak

After patch:
  TESTED: No overlap
  TESTED: Partial overlap
  TESTED: Partial overlap
  TESTED: No overlap
  TESTED: Full overlap
  success: perf_hwbreak

Fixes: 39413ae00967 ("powerpc/hw_breakpoints: Rewrite 8xx breakpoints to allow any address range size.")
Reported-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
---
 arch/powerpc/kernel/hw_breakpoint.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 2462cd7c565c..d0854320bb50 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -331,11 +331,13 @@ int hw_breakpoint_handler(struct die_args *args)
 	}
 
 	info->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ;
-	if (!dar_within_range(regs->dar, info))
-		info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
-
-	if (!IS_ENABLED(CONFIG_PPC_8xx) && !stepping_handler(regs, bp, info))
-		goto out;
+	if (IS_ENABLED(CONFIG_PPC_8xx)) {
+		if (!dar_within_range(regs->dar, info))
+			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
+	} else {
+		if (!stepping_handler(regs, bp, info))
+			goto out;
+	}
 
 	/*
 	 * As a policy, the callback is invoked in a 'trigger-after-execute'
-- 
2.21.1