1 files changed, 80 insertions, 0 deletions
diff --git a/arch/s390/include/asm/entry-percpu.h b/arch/s390/include/asm/entry-percpu.h
new file mode 100644
index 000000000000..4ef47265cfce
--- /dev/null
+++ b/arch/s390/include/asm/entry-percpu.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ARCH_S390_ENTRY_PERCPU_H
+#define ARCH_S390_ENTRY_PERCPU_H
+
+#include <linux/kprobes.h>
+#include <linux/percpu.h>
+#include <asm/lowcore.h>
+#include <asm/ptrace.h>
+#include <asm/asm-offsets.h>
+
+static __always_inline void percpu_entry(struct pt_regs *regs)
+{
+	struct lowcore *lc = get_lowcore();
+
+	if (user_mode(regs))
+		return;
+	regs->cpu = lc->cpu_nr;
+	regs->percpu_register = lc->percpu_register;
+	lc->percpu_register = 0;
+}
+
+static __always_inline bool percpu_code_check(struct pt_regs *regs)
+{
+	unsigned int insn, disp;
+	struct kprobe *p;
+
+	if (likely(user_mode(regs) || !regs->percpu_register))
+		return false;
+	/*
+	 * Within a percpu code section - check if the percpu base register
+	 * needs to be updated. This is the case if the PSW does not point to
+	 * the ADD instruction within the section.
+	 * - AG %rx,percpu_offset_in_lowcore(%r0,%r0)
+	 * which adds the percpu offset to the percpu base register.
+	 */
+	lockdep_assert_preemption_disabled();
+again:
+	insn = READ_ONCE(*(u16 *)psw_bits(regs->psw).ia);
+	if (unlikely(insn == BREAKPOINT_INSTRUCTION)) {
+		p = get_kprobe((void *)psw_bits(regs->psw).ia);
+		/*
+		 * If the kprobe is concurrently removed on a different CPU
+		 * it might not be found anymore. However text must have
+		 * been restored - try again.
+		 */
+		if (!p)
+			goto again;
+		insn = p->opcode;
+	}
+	if ((insn & 0xff0f) != 0xe300)
+		return true;
+	disp = offsetof(struct lowcore, percpu_offset);
+	if (machine_has_relocated_lowcore())
+		disp += LOWCORE_ALT_ADDRESS;
+	insn = (disp & 0xff000) >> 4 | (disp & 0x00fff) << 16 | 0x8;
+	if (*(u32 *)(psw_bits(regs->psw).ia + 2) != insn)
+		return true;
+	return false;
+}
+
+static __always_inline void percpu_exit(struct pt_regs *regs, bool needs_fixup)
+{
+	struct lowcore *lc = get_lowcore();
+	unsigned char reg;
+
+	if (user_mode(regs))
+		return;
+	reg = regs->percpu_register;
+	lc->percpu_register = reg;
+	if (likely(!needs_fixup))
+		return;
+	/* Check if process has been migrated to a different CPU. */
+	if (regs->cpu == lc->cpu_nr)
+		return;
+	/* Fixup percpu base register */
+	regs->gprs[reg] -= __per_cpu_offset[regs->cpu];
+	regs->gprs[reg] += lc->percpu_offset;
+}
+
+#endif