s390/perf: add perf_regs support and user stack dump

Add s390 support to dump user stack to user space for DWARF
stack unwinding.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-and-tested-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Kconfig

@@ -159,6 +159,8 @@ config S390
 	select HAVE_KRETPROBES
 	select HAVE_KVM
 	select HAVE_LIVEPATCH
+	select HAVE_PERF_REGS
+	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_MEMBLOCK
 	select HAVE_MEMBLOCK_NODE_MAP
 	select HAVE_MEMBLOCK_PHYS_MAP

arch/s390/include/uapi/asm/perf_regs.h

@@ -0,0 +1,27 @@
+#ifndef _ASM_S390_PERF_REGS_H
+#define _ASM_S390_PERF_REGS_H
+
+enum perf_event_s390_regs {
+	PERF_REG_S390_R0,
+	PERF_REG_S390_R1,
+	PERF_REG_S390_R2,
+	PERF_REG_S390_R3,
+	PERF_REG_S390_R4,
+	PERF_REG_S390_R5,
+	PERF_REG_S390_R6,
+	PERF_REG_S390_R7,
+	PERF_REG_S390_R8,
+	PERF_REG_S390_R9,
+	PERF_REG_S390_R10,
+	PERF_REG_S390_R11,
+	PERF_REG_S390_R12,
+	PERF_REG_S390_R13,
+	PERF_REG_S390_R14,
+	PERF_REG_S390_R15,
+	PERF_REG_S390_MASK,
+	PERF_REG_S390_PC,
+
+	PERF_REG_S390_MAX
+};
+
+#endif /* _ASM_S390_PERF_REGS_H */

arch/s390/kernel/Makefile

@@ -79,7 +79,7 @@ obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_UPROBES)		+= uprobes.o
 
 obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_cpum_cf.o perf_cpum_sf.o
-obj-$(CONFIG_PERF_EVENTS)	+= perf_cpum_cf_events.o
+obj-$(CONFIG_PERF_EVENTS)	+= perf_cpum_cf_events.o perf_regs.o
 
 obj-$(CONFIG_TRACEPOINTS)	+= trace.o
 

arch/s390/kernel/perf_regs.c

@@ -0,0 +1,49 @@
+#include <linux/perf_event.h>
+#include <linux/perf_regs.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/bug.h>
+#include <asm/ptrace.h>
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+	if (WARN_ON_ONCE((u32)idx >= PERF_REG_S390_MAX))
+		return 0;
+
+	if (idx == PERF_REG_S390_MASK)
+		return regs->psw.mask;
+	if (idx == PERF_REG_S390_PC)
+		return regs->psw.addr;
+
+	return regs->gprs[idx];
+}
+
+#define REG_RESERVED (~((1UL << PERF_REG_S390_MAX) - 1))
+
+int perf_reg_validate(u64 mask)
+{
+	if (!mask || mask & REG_RESERVED)
+		return -EINVAL;
+
+	return 0;
+}
+
+u64 perf_reg_abi(struct task_struct *task)
+{
+	if (test_tsk_thread_flag(task, TIF_31BIT))
+		return PERF_SAMPLE_REGS_ABI_32;
+
+	return PERF_SAMPLE_REGS_ABI_64;
+}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+			struct pt_regs *regs,
+			struct pt_regs *regs_user_copy)
+{
+	/*
+	 * Use the regs from the first interruption and let
+	 * perf_sample_regs_intr() handle interrupts (regs == get_irq_regs()).
+	 */
+	regs_user->regs = task_pt_regs(current);
+	regs_user->abi = perf_reg_abi(current);
+}