On 02/26/2014 12:00 AM, Will Deacon wrote:
On Tue, Feb 25, 2014 at 09:14:43AM +0000, AKASHI Takahiro wrote:
Currently syscall_trace() is called only for ptrace. With additional TIF_xx flags defined, it is now called in all the cases of audit, ftrace and seccomp in addition to ptrace.
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org Acked-by: Richard Guy Briggs rgb@redhat.com
arch/arm64/include/asm/thread_info.h | 13 ++++++++++ arch/arm64/kernel/entry.S | 5 ++-- arch/arm64/kernel/ptrace.c | 45 +++++++++++++++++----------------- 3 files changed, 38 insertions(+), 25 deletions(-)
[...]
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 6a8928b..c70133e 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -1062,31 +1062,30 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs) { 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;- }
- if (test_thread_flag(TIF_SYSCALL_TRACE)) {
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)
tracehook_report_syscall_exit(regs, 0);- else if (tracehook_report_syscall_entry(regs))
regs->syscallno = ~0UL;
if (dir)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;
if (is_compat_task())regs->regs[12] = saved_reg;elseregs->regs[7] = saved_reg;- }
Aren't these changes (to ptrace.c) just a giant NOP?
Umm, the purpose of this big "if" is to run the code only if TIF_SYSCALL_TRACE is set, and to make it easy to add additional hooks, audit and ftrace, around tracehook_report_*() later on.
-Takahiro AKASHI
Will