[PATCH 6/6] arm64: ptrace: add support for syscall emulation

Sudeep Holla
2019-02-28T18:34:13Z

Add PTRACE_SYSEMU and PTRACE_SYSEMU_SINGLESTEP support on arm64.
We can just make sure of the generic ptrace_syscall_enter hook to
support PTRACE_SYSEMU. We don't need any special handling for
PTRACE_SYSEMU_SINGLESTEP.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
arch/arm64/include/asm/thread_info.h | 5 ++++-
arch/arm64/kernel/ptrace.c | 3 +++
2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index bbca68b54732..c86aeb6379d5 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -75,6 +75,7 @@ void arch_release_task_struct(struct task_struct *tsk);
* TIF_SYSCALL_TRACE - syscall trace active
* TIF_SYSCALL_TRACEPOINT - syscall tracepoint for ftrace
* TIF_SYSCALL_AUDIT - syscall auditing
+ * TIF_SYSCALL_EMU - syscall emulation active
* TIF_SECOMP - syscall secure computing
* TIF_SIGPENDING - signal pending
* TIF_NEED_RESCHED - rescheduling necessary
@@ -92,6 +93,7 @@ void arch_release_task_struct(struct task_struct *tsk);
#define TIF_SYSCALL_AUDIT 9
#define TIF_SYSCALL_TRACEPOINT 10
#define TIF_SECCOMP 11
+#define TIF_SYSCALL_EMU 12
#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
#define TIF_FREEZE 19
#define TIF_RESTORE_SIGMASK 20
@@ -110,6 +112,7 @@ void arch_release_task_struct(struct task_struct *tsk);
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
#define _TIF_SECCOMP (1 << TIF_SECCOMP)
+#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
#define _TIF_UPROBE (1 << TIF_UPROBE)
#define _TIF_FSCHECK (1 << TIF_FSCHECK)
#define _TIF_32BIT (1 << TIF_32BIT)
@@ -121,7 +124,7 @@ void arch_release_task_struct(struct task_struct *tsk);

#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
_TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
- _TIF_NOHZ)
+ _TIF_NOHZ | _TIF_SYSCALL_EMU)

#define INIT_THREAD_INFO(tsk) \
{ \
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index ddaea0fd2fa4..c377ce597f92 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -1672,6 +1672,9 @@ static void tracehook_report_syscall(struct pt_regs *regs,

int syscall_trace_enter(struct pt_regs *regs)
{
+ if (unlikely(ptrace_syscall_enter(regs)))
+ return -1;
+
if (test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);

--
2.17.1