linux-kernel - [RFC PATCH 1/2] arm64: Pass registers to all single-step handling routines

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Message-Id: <20200213031131.13255-2-minyard@acm.org>
Date:   Wed, 12 Feb 2020 21:11:30 -0600
From:   minyard@....org
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, Corey Minyard <cminyard@...sta.com>
Subject: [RFC PATCH 1/2] arm64: Pass registers to all single-step handling routines

From: Corey Minyard <cminyard@...sta.com>

Get ready to set the SS bit in the MDSCR register in the kernel restore
handler.

Signed-off-by: Corey Minyard <cminyard@...sta.com>
---
 arch/arm64/include/asm/debug-monitors.h | 4 ++--
 arch/arm64/kernel/debug-monitors.c      | 4 ++--
 arch/arm64/kernel/hw_breakpoint.c       | 6 +++---
 arch/arm64/kernel/kgdb.c                | 6 +++---
 arch/arm64/kernel/probes/kprobes.c      | 4 ++--
 5 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h
index 7619f473155f..73ce974bf754 100644
--- a/arch/arm64/include/asm/debug-monitors.h
+++ b/arch/arm64/include/asm/debug-monitors.h
@@ -111,8 +111,8 @@ void user_rewind_single_step(struct task_struct *task);
 void user_fastforward_single_step(struct task_struct *task);
 
 void kernel_enable_single_step(struct pt_regs *regs);
-void kernel_disable_single_step(void);
-int kernel_active_single_step(void);
+void kernel_disable_single_step(struct pt_regs *regs);
+int kernel_active_single_step(struct pt_regs *regs);
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 int reinstall_suspended_bps(struct pt_regs *regs);
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 48222a4760c2..2a0dfd8b1265 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -414,7 +414,7 @@ void kernel_enable_single_step(struct pt_regs *regs)
 }
 NOKPROBE_SYMBOL(kernel_enable_single_step);
 
-void kernel_disable_single_step(void)
+void kernel_disable_single_step(struct pt_regs *regs)
 {
 	WARN_ON(!irqs_disabled());
 	mdscr_write(mdscr_read() & ~DBG_MDSCR_SS);
@@ -422,7 +422,7 @@ void kernel_disable_single_step(void)
 }
 NOKPROBE_SYMBOL(kernel_disable_single_step);
 
-int kernel_active_single_step(void)
+int kernel_active_single_step(struct pt_regs *regs)
 {
 	WARN_ON(!irqs_disabled());
 	return mdscr_read() & DBG_MDSCR_SS;
diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
index 0b727edf4104..785c9a5060a6 100644
--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -682,7 +682,7 @@ static int breakpoint_handler(unsigned long unused, unsigned int esr,
 		if (*kernel_step != ARM_KERNEL_STEP_NONE)
 			return 0;
 
-		if (kernel_active_single_step()) {
+		if (kernel_active_single_step(regs)) {
 			*kernel_step = ARM_KERNEL_STEP_SUSPEND;
 		} else {
 			*kernel_step = ARM_KERNEL_STEP_ACTIVE;
@@ -825,7 +825,7 @@ static int watchpoint_handler(unsigned long addr, unsigned int esr,
 		if (*kernel_step != ARM_KERNEL_STEP_NONE)
 			return 0;
 
-		if (kernel_active_single_step()) {
+		if (kernel_active_single_step(regs)) {
 			*kernel_step = ARM_KERNEL_STEP_SUSPEND;
 		} else {
 			*kernel_step = ARM_KERNEL_STEP_ACTIVE;
@@ -882,7 +882,7 @@ int reinstall_suspended_bps(struct pt_regs *regs)
 			toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1);
 
 		if (*kernel_step != ARM_KERNEL_STEP_SUSPEND) {
-			kernel_disable_single_step();
+			kernel_disable_single_step(regs);
 			handled_exception = 1;
 		} else {
 			handled_exception = 0;
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
index 43119922341f..220fe8fd6ace 100644
--- a/arch/arm64/kernel/kgdb.c
+++ b/arch/arm64/kernel/kgdb.c
@@ -200,8 +200,8 @@ int kgdb_arch_handle_exception(int exception_vector, int signo,
 		/*
 		 * Received continue command, disable single step
 		 */
-		if (kernel_active_single_step())
-			kernel_disable_single_step();
+		if (kernel_active_single_step(linux_regs))
+			kernel_disable_single_step(linux_regs);
 
 		err = 0;
 		break;
@@ -221,7 +221,7 @@ int kgdb_arch_handle_exception(int exception_vector, int signo,
 		/*
 		 * Enable single step handling
 		 */
-		if (!kernel_active_single_step())
+		if (!kernel_active_single_step(linux_regs))
 			kernel_enable_single_step(linux_regs);
 		err = 0;
 		break;
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index d1c95dcf1d78..3082dfc3cd99 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -308,7 +308,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
 		if (!instruction_pointer(regs))
 			BUG();
 
-		kernel_disable_single_step();
+		kernel_disable_single_step(regs);
 
 		if (kcb->kprobe_status == KPROBE_REENTER)
 			restore_previous_kprobe(kcb);
@@ -415,7 +415,7 @@ kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr)
 
 	if (retval == DBG_HOOK_HANDLED) {
 		kprobes_restore_local_irqflag(kcb, regs);
-		kernel_disable_single_step();
+		kernel_disable_single_step(regs);
 
 		post_kprobe_handler(kcb, regs);
 	}
-- 
2.17.1