[PATCH 3/6] x86: clean up _TIF_SYSCALL_EMU handling using ptrace_syscall_enter hook
From: Sudeep Holla <hidden>
Date: 2019-02-28 18:32:41
Also in:
linux-arm-kernel, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit), x86 entry code · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski
Now that we have a new hook ptrace_syscall_enter that can be called from syscall entry code and it handles PTRACE_SYSEMU in generic code, we can do some cleanup using the same in syscall_trace_enter. Further the extra logic to find single stepping PTRACE_SYSEMU_SINGLESTEP in syscall_slow_exit_work seems unnecessary. Let's remove the same. Cc: Andy Lutomirski <luto@kernel.org> Cc: Thomas Gleixner <redacted> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Signed-off-by: Sudeep Holla <redacted> --- arch/x86/entry/common.c | 22 ++++------------------ 1 file changed, 4 insertions(+), 18 deletions(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 7bc105f47d21..36457c1f87d2 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c@@ -70,22 +70,16 @@ static long syscall_trace_enter(struct pt_regs *regs) struct thread_info *ti = current_thread_info(); unsigned long ret = 0; - bool emulated = false; u32 work; if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) BUG_ON(regs != task_pt_regs(current)); - work = READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY; - - if (unlikely(work & _TIF_SYSCALL_EMU)) - emulated = true; - - if ((emulated || (work & _TIF_SYSCALL_TRACE)) && - tracehook_report_syscall_entry(regs)) + if (unlikely(ptrace_syscall_enter(regs))) return -1L; - if (emulated) + work = READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY; + if ((work & _TIF_SYSCALL_TRACE) && tracehook_report_syscall_entry(regs)) return -1L; #ifdef CONFIG_SECCOMP
@@ -227,15 +221,7 @@ static void syscall_slow_exit_work(struct pt_regs *regs, u32 cached_flags) if (cached_flags & _TIF_SYSCALL_TRACEPOINT) trace_sys_exit(regs, regs->ax); - /* - * If TIF_SYSCALL_EMU is set, we only get here because of - * TIF_SINGLESTEP (i.e. this is PTRACE_SYSEMU_SINGLESTEP). - * We already reported this syscall instruction in - * syscall_trace_enter(). - */ - step = unlikely( - (cached_flags & (_TIF_SINGLESTEP | _TIF_SYSCALL_EMU)) - == _TIF_SINGLESTEP); + step = unlikely((cached_flags & _TIF_SINGLESTEP)); if (step || cached_flags & _TIF_SYSCALL_TRACE) tracehook_report_syscall_exit(regs, step); }
--
2.17.1