From e08658a657f974590809290c62e889f0fd420200 Mon Sep 17 00:00:00 2001
From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Date: Sat, 22 Feb 2020 13:50:49 +0530
Subject: [PATCH] powerpc/watchpoint: Don't call dar_within_range() for Book3S

References: jsc#SLE-12936
Patch-mainline: v5.6-rc5
Git-commit: e08658a657f974590809290c62e889f0fd420200

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@ellerman.id.au>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200222082049.330435-1-ravi.bangoria@linux.ibm.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 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'
-- 
2.26.2