From c3f68b0478e7c07769394d17ebde0626600a7e1d Mon Sep 17 00:00:00 2001
From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Date: Thu, 17 Oct 2019 15:02:00 +0530
Subject: [PATCH] powerpc/watchpoint: Fix ptrace code that muck around with
 address/len

References: jsc#SLE-12936
Patch-mainline: v5.5-rc1
Git-commit: c3f68b0478e7c07769394d17ebde0626600a7e1d

ptrace_set_debugreg() does not consider new length while overwriting
the watchpoint. Fix that. ppc_set_hwdebug() aligns watchpoint address
to doubleword boundary but does not change the length. If address
range is crossing doubleword boundary and length is less then 8, we
will lose samples from second doubleword. So fix that as well.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191017093204.7511-4-ravi.bangoria@linux.ibm.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/include/asm/hw_breakpoint.h | 4 ++--
 arch/powerpc/kernel/ptrace.c             | 9 +++------
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index ea91ac7f5a27..27ac6f5d2891 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -34,6 +34,8 @@ struct arch_hw_breakpoint {
 #define HW_BRK_TYPE_PRIV_ALL	(HW_BRK_TYPE_USER | HW_BRK_TYPE_KERNEL | \
 				 HW_BRK_TYPE_HYP)
 
+#define HW_BREAKPOINT_ALIGN 0x7
+
 #define DABR_MAX_LEN	8
 #define DAWR_MAX_LEN	512
 
@@ -48,8 +50,6 @@ struct pmu;
 struct perf_sample_data;
 struct task_struct;
 
-#define HW_BREAKPOINT_ALIGN 0x7
-
 extern int hw_breakpoint_slots(int type);
 extern int arch_bp_generic_fields(int type, int *gen_bp_type);
 extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index c2dc93157b99..25c0424e8868 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -2440,6 +2440,7 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
 	if (bp) {
 		attr = bp->attr;
 		attr.bp_addr = hw_brk.address;
+		attr.bp_len = DABR_MAX_LEN;
 		arch_bp_generic_fields(hw_brk.type, &attr.bp_type);
 
 		/* Enable breakpoint */
@@ -2881,7 +2882,7 @@ static long ppc_set_hwdebug(struct task_struct *child,
 	if ((unsigned long)bp_info->addr >= TASK_SIZE)
 		return -EIO;
 
-	brk.address = bp_info->addr & ~7UL;
+	brk.address = bp_info->addr & ~HW_BREAKPOINT_ALIGN;
 	brk.type = HW_BRK_TYPE_TRANSLATE;
 	brk.len = DABR_MAX_LEN;
 	if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
@@ -2889,10 +2890,6 @@ static long ppc_set_hwdebug(struct task_struct *child,
 	if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)
 		brk.type |= HW_BRK_TYPE_WRITE;
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-	/*
-	 * Check if the request is for 'range' breakpoints. We can
-	 * support it if range < 8 bytes.
-	 */
 	if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE)
 		len = bp_info->addr2 - bp_info->addr;
 	else if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_EXACT)
@@ -2905,7 +2902,7 @@ static long ppc_set_hwdebug(struct task_struct *child,
 
 	/* Create a new breakpoint request if one doesn't exist already */
 	hw_breakpoint_init(&attr);
-	attr.bp_addr = (unsigned long)bp_info->addr & ~HW_BREAKPOINT_ALIGN;
+	attr.bp_addr = (unsigned long)bp_info->addr;
 	attr.bp_len = len;
 	arch_bp_generic_fields(brk.type, &attr.bp_type);
 
-- 
2.26.2