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arm64: split syscall_trace() into separate functions for enter/exit

Browse source 
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 <will.deacon@arm.com>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
AKASHI Takahiro 2014-04-30 10:51:30 +01:00 committed by Catalin Marinas
parent 449f81a4da
commit 3157858fef
2 changed files with 33 additions and 27 deletions
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10
arch/arm64/kernel/entry.S
View file

@ -628,9 +628,8 @@ 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
@ -645,9 +644,8 @@ __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
/*

50
arch/arm64/kernel/ptrace.c
View file

@ -1058,35 +1058,43 @@ long arch_ptrace(struct task_struct *child, long request,
return ptrace_request(child, request, addr, data);
}
asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
enum ptrace_syscall_dir {
PTRACE_SYSCALL_ENTER = 0,
PTRACE_SYSCALL_EXIT,
};
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;
/*
* 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 (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;
}
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);
}