LoongArch: Add uprobes support

Uprobes is the user-space counterpart to kprobes, this patch adds
uprobes support for LoongArch.

Here is a simple example with CONFIG_UPROBE_EVENTS=y:

  # cat test.c
  #include <stdio.h>

  int add(int a, int b)
  {
  	  return a + b;
  }

  int main()
  {
	  return add(2, 7);
  }
  # gcc test.c -o /tmp/test
  # nm /tmp/test | grep add
  0000000120004194 T add
  # cd /sys/kernel/debug/tracing
  # echo > uprobe_events
  # echo "p:myuprobe /tmp/test:0x4194 %r4 %r5" > uprobe_events
  # echo "r:myuretprobe /tmp/test:0x4194 %r4" >> uprobe_events
  # echo 1 > events/uprobes/enable
  # echo 1 > tracing_on
  # /tmp/test
  # cat trace
  ...
  #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
  #              | |         |   |||||     |         |
              test-1060    [001] DNZff  1015.770620: myuprobe: (0x120004194) arg1=0x2 arg2=0x7
              test-1060    [001] DNZff  1015.770930: myuretprobe: (0x1200041f0 <- 0x120004194) arg1=0x9

Tested-by: Jeff Xie <xiehuan09@gmail.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 36 insertions, 0 deletions

diff --git a/arch/loongarch/include/asm/uprobes.h b/arch/loongarch/include/asm/uprobes.h
new file mode 100644
index 000000000000..c8f59983f702
--- /dev/null
+++ b/arch/loongarch/include/asm/uprobes.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_LOONGARCH_UPROBES_H
+#define __ASM_LOONGARCH_UPROBES_H
+
+#include <asm/inst.h>
+
+typedef u32 uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES		8
+#define UPROBE_XOL_SLOT_BYTES	MAX_UINSN_BYTES
+
+#define UPROBE_SWBP_INSN	larch_insn_gen_break(BRK_UPROBE_BP)
+#define UPROBE_SWBP_INSN_SIZE	LOONGARCH_INSN_SIZE
+
+#define UPROBE_XOLBP_INSN	larch_insn_gen_break(BRK_UPROBE_XOLBP)
+
+struct arch_uprobe {
+	unsigned long	resume_era;
+	u32	insn[2];
+	u32	ixol[2];
+	bool	simulate;
+};
+
+struct arch_uprobe_task {
+	unsigned long saved_trap_nr;
+};
+
+#ifdef CONFIG_UPROBES
+bool uprobe_breakpoint_handler(struct pt_regs *regs);
+bool uprobe_singlestep_handler(struct pt_regs *regs);
+#else /* !CONFIG_UPROBES */
+static inline bool uprobe_breakpoint_handler(struct pt_regs *regs) { return false; }
+static inline bool uprobe_singlestep_handler(struct pt_regs *regs) { return false; }
+#endif /* CONFIG_UPROBES */
+
+#endif /* __ASM_LOONGARCH_UPROBES_H */