parisc: Add initial kernel-side perf_event support

Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/Kconfig

@@ -31,6 +31,9 @@ config PARISC
 	select HAVE_KERNEL_UNCOMPRESSED
 	select HAVE_PCI
 	select HAVE_PERF_EVENTS
+	select HAVE_PERF_REGS
+	select HAVE_PERF_USER_STACK_DUMP
+	select PERF_USE_VMALLOC
 	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZ4

arch/parisc/include/asm/perf_event.h

@@ -1,6 +1,12 @@
 #ifndef __ASM_PARISC_PERF_EVENT_H
 #define __ASM_PARISC_PERF_EVENT_H
 
-/* Empty, just to avoid compiling error */
+#include <asm/psw.h>
+
+#define perf_arch_fetch_caller_regs(regs, __ip) { \
+	(regs)->gr[0] = KERNEL_PSW; \
+	(regs)->iaoq[0] = (__ip); \
+	asm volatile("copy %%sp, %0\n":"=r"((regs)->gr[30])); \
+}
 
 #endif /* __ASM_PARISC_PERF_EVENT_H */

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

@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_ASM_PARISC_PERF_REGS_H
+#define _UAPI_ASM_PARISC_PERF_REGS_H
+
+/* see struct user_regs_struct */
+enum perf_event_parisc_regs {
+	PERF_REG_PARISC_R0,	/* PSW is in gr[0] */
+	PERF_REG_PARISC_R1,
+	PERF_REG_PARISC_R2,
+	PERF_REG_PARISC_R3,
+	PERF_REG_PARISC_R4,
+	PERF_REG_PARISC_R5,
+	PERF_REG_PARISC_R6,
+	PERF_REG_PARISC_R7,
+	PERF_REG_PARISC_R8,
+	PERF_REG_PARISC_R9,
+	PERF_REG_PARISC_R10,
+	PERF_REG_PARISC_R11,
+	PERF_REG_PARISC_R12,
+	PERF_REG_PARISC_R13,
+	PERF_REG_PARISC_R14,
+	PERF_REG_PARISC_R15,
+	PERF_REG_PARISC_R16,
+	PERF_REG_PARISC_R17,
+	PERF_REG_PARISC_R18,
+	PERF_REG_PARISC_R19,
+	PERF_REG_PARISC_R20,
+	PERF_REG_PARISC_R21,
+	PERF_REG_PARISC_R22,
+	PERF_REG_PARISC_R23,
+	PERF_REG_PARISC_R24,
+	PERF_REG_PARISC_R25,
+	PERF_REG_PARISC_R26,
+	PERF_REG_PARISC_R27,
+	PERF_REG_PARISC_R28,
+	PERF_REG_PARISC_R29,
+	PERF_REG_PARISC_R30,
+	PERF_REG_PARISC_R31,
+
+	PERF_REG_PARISC_SR0,
+	PERF_REG_PARISC_SR1,
+	PERF_REG_PARISC_SR2,
+	PERF_REG_PARISC_SR3,
+	PERF_REG_PARISC_SR4,
+	PERF_REG_PARISC_SR5,
+	PERF_REG_PARISC_SR6,
+	PERF_REG_PARISC_SR7,
+
+	PERF_REG_PARISC_IAOQ0,
+	PERF_REG_PARISC_IAOQ1,
+	PERF_REG_PARISC_IASQ0,
+	PERF_REG_PARISC_IASQ1,
+
+	PERF_REG_PARISC_SAR,	/* CR11 */
+	PERF_REG_PARISC_IIR,	/* CR19 */
+	PERF_REG_PARISC_ISR,	/* CR20 */
+	PERF_REG_PARISC_IOR,	/* CR21 */
+	PERF_REG_PARISC_IPSW,	/* CR22 */
+
+	PERF_REG_PARISC_MAX
+};
+
+#endif /* _UAPI_ASM_PARISC_PERF_REGS_H */

arch/parisc/kernel/Makefile

@@ -38,6 +38,7 @@ obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY)	+= topology.o
 obj-$(CONFIG_FUNCTION_TRACER)		+= ftrace.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o
 obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
+obj-$(CONFIG_PERF_EVENTS)		+= perf_event.o perf_regs.o
 obj-$(CONFIG_KGDB)			+= kgdb.o
 obj-$(CONFIG_KPROBES)			+= kprobes.o
 obj-$(CONFIG_KEXEC_CORE)		+= kexec.o relocate_kernel.o

arch/parisc/kernel/perf_event.c

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Performance event support for parisc
+ *
+ * Copyright (C) 2025 by Helge Deller <deller@gmx.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <asm/unwind.h>
+
+void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
+			   struct pt_regs *regs)
+{
+
+	struct unwind_frame_info info;
+
+	unwind_frame_init_task(&info, current, NULL);
+	while (1) {
+		if (unwind_once(&info) < 0 || info.ip == 0)
+			break;
+
+		if (!__kernel_text_address(info.ip) ||
+			perf_callchain_store(entry, info.ip))
+				return;
+	}
+}

arch/parisc/kernel/perf_regs.c

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Copyright (C) 2025 by Helge Deller <deller@gmx.de> */
+
+#include <linux/perf_event.h>
+#include <linux/perf_regs.h>
+#include <asm/ptrace.h>
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+	switch (idx) {
+	case PERF_REG_PARISC_R0 ... PERF_REG_PARISC_R31:
+		return regs->gr[idx - PERF_REG_PARISC_R0];
+	case PERF_REG_PARISC_SR0 ... PERF_REG_PARISC_SR7:
+		return regs->sr[idx - PERF_REG_PARISC_SR0];
+	case PERF_REG_PARISC_IASQ0 ... PERF_REG_PARISC_IASQ1:
+		return regs->iasq[idx - PERF_REG_PARISC_IASQ0];
+	case PERF_REG_PARISC_IAOQ0 ... PERF_REG_PARISC_IAOQ1:
+		return regs->iasq[idx - PERF_REG_PARISC_IAOQ0];
+	case PERF_REG_PARISC_SAR:	/* CR11 */
+		return regs->sar;
+	case PERF_REG_PARISC_IIR:	/* CR19 */
+		return regs->iir;
+	case PERF_REG_PARISC_ISR:	/* CR20 */
+		return regs->isr;
+	case PERF_REG_PARISC_IOR:	/* CR21 */
+		return regs->ior;
+	case PERF_REG_PARISC_IPSW:	/* CR22 */
+		return regs->ipsw;
+	};
+	WARN_ON_ONCE((u32)idx >= PERF_REG_PARISC_MAX);
+	return 0;
+}
+
+#define REG_RESERVED (~((1ULL << PERF_REG_PARISC_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 (!IS_ENABLED(CONFIG_64BIT))
+		return PERF_SAMPLE_REGS_ABI_32;
+
+	if (test_tsk_thread_flag(task, TIF_32BIT))
+		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)
+{
+	regs_user->regs = task_pt_regs(current);
+	regs_user->abi = perf_reg_abi(current);
+}