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arm64: ptrace: add support for syscall emulation
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Add PTRACE_SYSEMU and PTRACE_SYSEMU_SINGLESTEP support on arm64.
We don't need any special handling for PTRACE_SYSEMU_SINGLESTEP.

It's quite difficult to generalize handling PTRACE_SYSEMU cross
architectures and avoid calls to tracehook_report_syscall_entry twice.
Different architecture have different mechanism to indicate NO_SYSCALL
and trying to generalise adds more code for no gain.

Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Sudeep Holla authored and Catalin Marinas committed Jun 5, 2019
1 parent fd38663 commit f086f67
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Showing 2 changed files with 9 additions and 2 deletions.
5 changes: 4 additions & 1 deletion arch/arm64/include/asm/thread_info.h
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -91,6 +92,7 @@ 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
Expand All @@ -109,6 +111,7 @@ 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)
Expand All @@ -120,7 +123,7 @@ 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) \
{ \
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6 changes: 5 additions & 1 deletion arch/arm64/kernel/ptrace.c
Original file line number Diff line number Diff line change
Expand Up @@ -1819,8 +1819,12 @@ static void tracehook_report_syscall(struct pt_regs *regs,

int syscall_trace_enter(struct pt_regs *regs)
{
if (test_thread_flag(TIF_SYSCALL_TRACE))
if (test_thread_flag(TIF_SYSCALL_TRACE) ||
test_thread_flag(TIF_SYSCALL_EMU)) {
tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
if (!in_syscall(regs) || test_thread_flag(TIF_SYSCALL_EMU))
return -1;
}

/* Do the secure computing after ptrace; failures should be fast. */
if (secure_computing(NULL) == -1)
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