[PATCH v10 12/16] entry: Add arch_ptrace_report_syscall_entry/exit()

[Jinjie Ruan]

Differ from generic entry, due to historical reasons, ARM64 need to
save/restore during syscall entry/exit because ARM64 use a scratch
register (ip(r12) on AArch32, x7 on AArch64) to denote syscall entry/exit.

In preparation for moving arm64 over to the generic entry code,
add arch_ptrace_report_syscall_entry/exit() as the default
ptrace_report_syscall_entry/exit() implementation. This allows
arm64 to implement the architecture specific version.

This allows arm64 to implement the architecture specific version.

Reviewed-by: Kevin Brodsky <kevin.brodsky at arm.com>
Suggested-by: Mark Rutland <mark.rutland at arm.com>
Suggested-by: Thomas Gleixner <tglx at linutronix.de>
Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
---
 include/linux/entry-common.h  | 39 +++++++++++++++++++++++++++++++++++
 kernel/entry/syscall-common.c |  4 ++--
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 0de0e60630e1..17171e8873fc 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -45,6 +45,25 @@
 				 SYSCALL_WORK_SYSCALL_EXIT_TRAP	|	\
 				 ARCH_SYSCALL_WORK_EXIT)
 
+/**
+ * arch_ptrace_report_syscall_entry - Architecture specific
+ *				      ptrace_report_syscall_entry().
+ *
+ * Invoked from syscall_trace_enter() to wrap ptrace_report_syscall_entry().
+ * Defaults to ptrace_report_syscall_entry.
+ *
+ * The main purpose is to support arch-specific ptrace_report_syscall_entry()
+ * implementation.
+ */
+static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs);
+
+#ifndef arch_ptrace_report_syscall_entry
+static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs)
+{
+	return ptrace_report_syscall_entry(regs);
+}
+#endif
+
 long syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long work);
 
 /**
@@ -112,6 +131,26 @@ static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, l
 	return ret;
 }
 
+/**
+ * arch_ptrace_report_syscall_exit - Architecture specific
+ *				     ptrace_report_syscall_exit.
+ *
+ * Invoked from syscall_exit_work() to wrap ptrace_report_syscall_exit().
+ *
+ * The main purpose is to support arch-specific ptrace_report_syscall_exit
+ * implementation.
+ */
+static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
+							    int step);
+
+#ifndef arch_ptrace_report_syscall_exit
+static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
+							    int step)
+{
+	ptrace_report_syscall_exit(regs, step);
+}
+#endif
+
 /**
  * syscall_exit_work - Handle work before returning to user mode
  * @regs:	Pointer to current pt_regs
diff --git a/kernel/entry/syscall-common.c b/kernel/entry/syscall-common.c
index 940a597ded40..fe38f84dfff3 100644
--- a/kernel/entry/syscall-common.c
+++ b/kernel/entry/syscall-common.c
@@ -34,7 +34,7 @@ long syscall_trace_enter(struct pt_regs *regs, long syscall,
 
 	/* Handle ptrace */
 	if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
-		ret = ptrace_report_syscall_entry(regs);
+		ret = arch_ptrace_report_syscall_entry(regs);
 		if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))
 			return -1L;
 	}
@@ -100,5 +100,5 @@ void syscall_exit_work(struct pt_regs *regs, unsigned long work)
 
 	step = report_single_step(work);
 	if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
-		ptrace_report_syscall_exit(regs, step);
+		arch_ptrace_report_syscall_exit(regs, step);
 }
-- 
2.34.1