powerpc/watchpoint: Move DAWR detection logic outside of hw_breakpoint.c

Power10 hw has multiple DAWRs but hw doesn't tell which DAWR caused
the exception. So we have a sw logic to detect that in hw_breakpoint.c.
But hw_breakpoint.c gets compiled only with CONFIG_HAVE_HW_BREAKPOINT=Y.
Move DAWR detection logic outside of hw_breakpoint.c so that it can be
reused when CONFIG_HAVE_HW_BREAKPOINT is not set.
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/20200902042945.129369-5-ravi.bangoria@linux.ibm.com

arch/powerpc/include/asm/hw_breakpoint.h

@@ -10,6 +10,7 @@
 #define _PPC_BOOK3S_64_HW_BREAKPOINT_H
 
 #include <asm/cpu_has_feature.h>
+#include <asm/inst.h>
 
 #ifdef	__KERNEL__
 struct arch_hw_breakpoint {
@@ -52,6 +53,13 @@ static inline int nr_wp_slots(void)
 	return cpu_has_feature(CPU_FTR_DAWR1) ? 2 : 1;
 }
 
+bool wp_check_constraints(struct pt_regs *regs, struct ppc_inst instr,
+			  unsigned long ea, int type, int size,
+			  struct arch_hw_breakpoint *info);
+
+void wp_get_instr_detail(struct pt_regs *regs, struct ppc_inst *instr,
+			 int *type, int *size, unsigned long *ea);
+
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 #include <linux/kdebug.h>
 #include <asm/reg.h>

arch/powerpc/kernel/Makefile

@@ -45,7 +45,8 @@ obj-y				:= cputable.o syscalls.o \
 				   signal.o sysfs.o cacheinfo.o time.o \
 				   prom.o traps.o setup-common.o \
 				   udbg.o misc.o io.o misc_$(BITS).o \
-				   of_platform.o prom_parse.o firmware.o
+				   of_platform.o prom_parse.o firmware.o \
+				   hw_breakpoint_constraints.o
 obj-y				+= ptrace/
 obj-$(CONFIG_PPC64)		+= setup_64.o \
 				   paca.o nvram_64.o note.o syscall_64.o

arch/powerpc/kernel/hw_breakpoint.c

@@ -494,161 +494,6 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
 	}
 }
 
-static bool dar_in_user_range(unsigned long dar, struct arch_hw_breakpoint *info)
-{
-	return ((info->address <= dar) && (dar - info->address < info->len));
-}
-
-static bool ea_user_range_overlaps(unsigned long ea, int size,
-				   struct arch_hw_breakpoint *info)
-{
-	return ((ea < info->address + info->len) &&
-		(ea + size > info->address));
-}
-
-static bool dar_in_hw_range(unsigned long dar, struct arch_hw_breakpoint *info)
-{
-	unsigned long hw_start_addr, hw_end_addr;
-
-	hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
-	hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);
-
-	return ((hw_start_addr <= dar) && (hw_end_addr > dar));
-}
-
-static bool ea_hw_range_overlaps(unsigned long ea, int size,
-				 struct arch_hw_breakpoint *info)
-{
-	unsigned long hw_start_addr, hw_end_addr;
-	unsigned long align_size = HW_BREAKPOINT_SIZE;
-
-	/*
-	 * On p10 predecessors, quadword is handle differently then
-	 * other instructions.
-	 */
-	if (!cpu_has_feature(CPU_FTR_ARCH_31) && size == 16)
-		align_size = HW_BREAKPOINT_SIZE_QUADWORD;
-
-	hw_start_addr = ALIGN_DOWN(info->address, align_size);
-	hw_end_addr = ALIGN(info->address + info->len, align_size);
-
-	return ((ea < hw_end_addr) && (ea + size > hw_start_addr));
-}
-
-/*
- * If hw has multiple DAWR registers, we also need to check all
- * dawrx constraint bits to confirm this is _really_ a valid event.
- * If type is UNKNOWN, but privilege level matches, consider it as
- * a positive match.
- */
-static bool check_dawrx_constraints(struct pt_regs *regs, int type,
-				    struct arch_hw_breakpoint *info)
-{
-	if (OP_IS_LOAD(type) && !(info->type & HW_BRK_TYPE_READ))
-		return false;
-
-	/*
-	 * The Cache Management instructions other than dcbz never
-	 * cause a match. i.e. if type is CACHEOP, the instruction
-	 * is dcbz, and dcbz is treated as Store.
-	 */
-	if ((OP_IS_STORE(type) || type == CACHEOP) && !(info->type & HW_BRK_TYPE_WRITE))
-		return false;
-
-	if (is_kernel_addr(regs->nip) && !(info->type & HW_BRK_TYPE_KERNEL))
-		return false;
-
-	if (user_mode(regs) && !(info->type & HW_BRK_TYPE_USER))
-		return false;
-
-	return true;
-}
-
-/*
- * Return true if the event is valid wrt dawr configuration,
- * including extraneous exception. Otherwise return false.
- */
-static bool check_constraints(struct pt_regs *regs, struct ppc_inst instr,
-			      unsigned long ea, int type, int size,
-			      struct arch_hw_breakpoint *info)
-{
-	bool in_user_range = dar_in_user_range(regs->dar, info);
-	bool dawrx_constraints;
-
-	/*
-	 * 8xx supports only one breakpoint and thus we can
-	 * unconditionally return true.
-	 */
-	if (IS_ENABLED(CONFIG_PPC_8xx)) {
-		if (!in_user_range)
-			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
-		return true;
-	}
-
-	if (unlikely(ppc_inst_equal(instr, ppc_inst(0)))) {
-		if (cpu_has_feature(CPU_FTR_ARCH_31) &&
-		    !dar_in_hw_range(regs->dar, info))
-			return false;
-
-		return true;
-	}
-
-	dawrx_constraints = check_dawrx_constraints(regs, type, info);
-
-	if (type == UNKNOWN) {
-		if (cpu_has_feature(CPU_FTR_ARCH_31) &&
-		    !dar_in_hw_range(regs->dar, info))
-			return false;
-
-		return dawrx_constraints;
-	}
-
-	if (ea_user_range_overlaps(ea, size, info))
-		return dawrx_constraints;
-
-	if (ea_hw_range_overlaps(ea, size, info)) {
-		if (dawrx_constraints) {
-			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
-			return true;
-		}
-	}
-	return false;
-}
-
-static int cache_op_size(void)
-{
-#ifdef __powerpc64__
-	return ppc64_caches.l1d.block_size;
-#else
-	return L1_CACHE_BYTES;
-#endif
-}
-
-static void get_instr_detail(struct pt_regs *regs, struct ppc_inst *instr,
-			     int *type, int *size, unsigned long *ea)
-{
-	struct instruction_op op;
-
-	if (__get_user_instr_inatomic(*instr, (void __user *)regs->nip))
-		return;
-
-	analyse_instr(&op, regs, *instr);
-	*type = GETTYPE(op.type);
-	*ea = op.ea;
-#ifdef __powerpc64__
-	if (!(regs->msr & MSR_64BIT))
-		*ea &= 0xffffffffUL;
-#endif
-
-	*size = GETSIZE(op.type);
-	if (*type == CACHEOP) {
-		*size = cache_op_size();
-		*ea &= ~(*size - 1);
-	} else if (*type == LOAD_VMX || *type == STORE_VMX) {
-		*ea &= ~(*size - 1);
-	}
-}
-
 static bool is_larx_stcx_instr(int type)
 {
 	return type == LARX || type == STCX;
@@ -732,7 +577,7 @@ int hw_breakpoint_handler(struct die_args *args)
 	rcu_read_lock();
 
 	if (!IS_ENABLED(CONFIG_PPC_8xx))
-		get_instr_detail(regs, &instr, &type, &size, &ea);
+		wp_get_instr_detail(regs, &instr, &type, &size, &ea);
 
 	for (i = 0; i < nr_wp_slots(); i++) {
 		bp[i] = __this_cpu_read(bp_per_reg[i]);
@@ -742,7 +587,7 @@ int hw_breakpoint_handler(struct die_args *args)
 		info[i] = counter_arch_bp(bp[i]);
 		info[i]->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ;
 
-		if (check_constraints(regs, instr, ea, type, size, info[i])) {
+		if (wp_check_constraints(regs, instr, ea, type, size, info[i])) {
 			if (!IS_ENABLED(CONFIG_PPC_8xx) &&
 			    ppc_inst_equal(instr, ppc_inst(0))) {
 				handler_error(bp[i], info[i]);

arch/powerpc/kernel/hw_breakpoint_constraints.c

+// SPDX-License-Identifier: GPL-2.0+
+#include <linux/kernel.h>
+#include <linux/uaccess.h>
+#include <linux/sched.h>
+#include <asm/hw_breakpoint.h>
+#include <asm/sstep.h>
+#include <asm/cache.h>
+
+static bool dar_in_user_range(unsigned long dar, struct arch_hw_breakpoint *info)
+{
+	return ((info->address <= dar) && (dar - info->address < info->len));
+}
+
+static bool ea_user_range_overlaps(unsigned long ea, int size,
+				   struct arch_hw_breakpoint *info)
+{
+	return ((ea < info->address + info->len) &&
+		(ea + size > info->address));
+}
+
+static bool dar_in_hw_range(unsigned long dar, struct arch_hw_breakpoint *info)
+{
+	unsigned long hw_start_addr, hw_end_addr;
+
+	hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
+	hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);
+
+	return ((hw_start_addr <= dar) && (hw_end_addr > dar));
+}
+
+static bool ea_hw_range_overlaps(unsigned long ea, int size,
+				 struct arch_hw_breakpoint *info)
+{
+	unsigned long hw_start_addr, hw_end_addr;
+	unsigned long align_size = HW_BREAKPOINT_SIZE;
+
+	/*
+	 * On p10 predecessors, quadword is handle differently then
+	 * other instructions.
+	 */
+	if (!cpu_has_feature(CPU_FTR_ARCH_31) && size == 16)
+		align_size = HW_BREAKPOINT_SIZE_QUADWORD;
+
+	hw_start_addr = ALIGN_DOWN(info->address, align_size);
+	hw_end_addr = ALIGN(info->address + info->len, align_size);
+
+	return ((ea < hw_end_addr) && (ea + size > hw_start_addr));
+}
+
+/*
+ * If hw has multiple DAWR registers, we also need to check all
+ * dawrx constraint bits to confirm this is _really_ a valid event.
+ * If type is UNKNOWN, but privilege level matches, consider it as
+ * a positive match.
+ */
+static bool check_dawrx_constraints(struct pt_regs *regs, int type,
+				    struct arch_hw_breakpoint *info)
+{
+	if (OP_IS_LOAD(type) && !(info->type & HW_BRK_TYPE_READ))
+		return false;
+
+	/*
+	 * The Cache Management instructions other than dcbz never
+	 * cause a match. i.e. if type is CACHEOP, the instruction
+	 * is dcbz, and dcbz is treated as Store.
+	 */
+	if ((OP_IS_STORE(type) || type == CACHEOP) && !(info->type & HW_BRK_TYPE_WRITE))
+		return false;
+
+	if (is_kernel_addr(regs->nip) && !(info->type & HW_BRK_TYPE_KERNEL))
+		return false;
+
+	if (user_mode(regs) && !(info->type & HW_BRK_TYPE_USER))
+		return false;
+
+	return true;
+}
+
+/*
+ * Return true if the event is valid wrt dawr configuration,
+ * including extraneous exception. Otherwise return false.
+ */
+bool wp_check_constraints(struct pt_regs *regs, struct ppc_inst instr,
+			  unsigned long ea, int type, int size,
+			  struct arch_hw_breakpoint *info)
+{
+	bool in_user_range = dar_in_user_range(regs->dar, info);
+	bool dawrx_constraints;
+
+	/*
+	 * 8xx supports only one breakpoint and thus we can
+	 * unconditionally return true.
+	 */
+	if (IS_ENABLED(CONFIG_PPC_8xx)) {
+		if (!in_user_range)
+			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
+		return true;
+	}
+
+	if (unlikely(ppc_inst_equal(instr, ppc_inst(0)))) {
+		if (cpu_has_feature(CPU_FTR_ARCH_31) &&
+		    !dar_in_hw_range(regs->dar, info))
+			return false;
+
+		return true;
+	}
+
+	dawrx_constraints = check_dawrx_constraints(regs, type, info);
+
+	if (type == UNKNOWN) {
+		if (cpu_has_feature(CPU_FTR_ARCH_31) &&
+		    !dar_in_hw_range(regs->dar, info))
+			return false;
+
+		return dawrx_constraints;
+	}
+
+	if (ea_user_range_overlaps(ea, size, info))
+		return dawrx_constraints;
+
+	if (ea_hw_range_overlaps(ea, size, info)) {
+		if (dawrx_constraints) {
+			info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
+			return true;
+		}
+	}
+	return false;
+}
+
+static int cache_op_size(void)
+{
+#ifdef __powerpc64__
+	return ppc64_caches.l1d.block_size;
+#else
+	return L1_CACHE_BYTES;
+#endif
+}
+
+void wp_get_instr_detail(struct pt_regs *regs, struct ppc_inst *instr,
+			 int *type, int *size, unsigned long *ea)
+{
+	struct instruction_op op;
+
+	if (__get_user_instr_inatomic(*instr, (void __user *)regs->nip))
+		return;
+
+	analyse_instr(&op, regs, *instr);
+	*type = GETTYPE(op.type);
+	*ea = op.ea;
+#ifdef __powerpc64__
+	if (!(regs->msr & MSR_64BIT))
+		*ea &= 0xffffffffUL;
+#endif
+
+	*size = GETSIZE(op.type);
+	if (*type == CACHEOP) {
+		*size = cache_op_size();
+		*ea &= ~(*size - 1);
+	} else if (*type == LOAD_VMX || *type == STORE_VMX) {
+		*ea &= ~(*size - 1);
+	}
+}