From 517f60a12daa74220479363dab0f098f22fd9e27 Mon Sep 17 00:00:00 2001 From: AKASHI Takahiro Date: Wed, 30 Apr 2014 10:51:30 +0100 Subject: [PATCH] arm64: split syscall_trace() into separate functions for enter/exit As done in arm, this change makes it easy to confirm we invoke syscall related hooks, including syscall tracepoint, audit and seccomp which would be implemented later, in correct order. That is, undoing operations in the opposite order on exit that they were done on entry. Acked-by: Will Deacon Signed-off-by: AKASHI Takahiro Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas (cherry picked from commit 3157858feff89196635b01495d5ec9ebe206639e) Signed-off-by: Mark Brown Conflicts: arch/arm64/kernel/ptrace.c --- arch/arm64/kernel/entry.S | 10 +++---- arch/arm64/kernel/ptrace.c | 58 ++++++++++++++++++-------------------- 2 files changed, 32 insertions(+), 36 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 21dc3415d488..538b826102e3 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -659,9 +659,8 @@ ENDPROC(el0_svc) * switches, and waiting for our parent to respond. */ __sys_trace: - mov x1, sp - mov w0, #0 // trace entry - bl syscall_trace + mov x0, sp + bl syscall_trace_enter adr lr, __sys_trace_return // return address uxtw scno, w0 // syscall number (possibly new) mov x1, sp // pointer to regs @@ -676,9 +675,8 @@ __sys_trace: __sys_trace_return: str x0, [sp] // save returned x0 - mov x1, sp - mov w0, #1 // trace exit - bl syscall_trace + mov x0, sp + bl syscall_trace_exit b ret_to_user /* diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 5341534b6d04..b43903472ac7 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -1109,45 +1109,43 @@ long arch_ptrace(struct task_struct *child, long request, return ptrace_request(child, request, addr, data); } +enum ptrace_syscall_dir { + PTRACE_SYSCALL_ENTER = 0, + PTRACE_SYSCALL_EXIT, +}; -static int __init ptrace_break_init(void) -{ - hook_debug_fault_code(DBG_ESR_EVT_BRK, arm64_break_trap, SIGTRAP, - TRAP_BRKPT, "ptrace BRK handler"); - return 0; -} -core_initcall(ptrace_break_init); - - -asmlinkage int syscall_trace(int dir, struct pt_regs *regs) +static void tracehook_report_syscall(struct pt_regs *regs, + enum ptrace_syscall_dir dir) { + int regno; unsigned long saved_reg; - if (!test_thread_flag(TIF_SYSCALL_TRACE)) - return regs->syscallno; - - if (is_compat_task()) { - /* AArch32 uses ip (r12) for scratch */ - saved_reg = regs->regs[12]; - regs->regs[12] = dir; - } else { - /* - * Save X7. X7 is used to denote syscall entry/exit: - * X7 = 0 -> entry, = 1 -> exit - */ - saved_reg = regs->regs[7]; - regs->regs[7] = dir; - } + /* + * A scratch register (ip(r12) on AArch32, x7 on AArch64) is + * used to denote syscall entry/exit: + */ + regno = (is_compat_task() ? 12 : 7); + saved_reg = regs->regs[regno]; + regs->regs[regno] = dir; - if (dir) + if (dir == PTRACE_SYSCALL_EXIT) tracehook_report_syscall_exit(regs, 0); else if (tracehook_report_syscall_entry(regs)) regs->syscallno = ~0UL; - if (is_compat_task()) - regs->regs[12] = saved_reg; - else - regs->regs[7] = saved_reg; + regs->regs[regno] = saved_reg; +} + +asmlinkage int syscall_trace_enter(struct pt_regs *regs) +{ + if (test_thread_flag(TIF_SYSCALL_TRACE)) + tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER); return regs->syscallno; } + +asmlinkage void syscall_trace_exit(struct pt_regs *regs) +{ + if (test_thread_flag(TIF_SYSCALL_TRACE)) + tracehook_report_syscall(regs, PTRACE_SYSCALL_EXIT); +} -- 2.34.1