| Message ID | 1394705491-12343-3-git-send-email-takahiro.akashi@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Mar 13, 2014 at 10:11:30AM +0000, AKASHI Takahiro wrote: > 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. > > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> > --- > arch/arm64/kernel/entry.S | 10 ++++----- > arch/arm64/kernel/ptrace.c | 48 ++++++++++++++++++++++++++++++++++---------- > 2 files changed, 41 insertions(+), 17 deletions(-) [...] > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 6a8928b..9993a8f 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -1058,29 +1058,27 @@ 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) > +asmlinkage int syscall_trace_enter(struct pt_regs *regs) > { > unsigned long saved_reg; > > if (!test_thread_flag(TIF_SYSCALL_TRACE)) > return regs->syscallno; > > + /* > + * A scrach register (ip(r12) on AArch32, x7 on AArch64) is > + * used to denote syscall entry/exit: > + * 0 -> entry > + */ You could add an enum, like we have on ARM (ptrace_syscall_dir) for the two directions. > if (is_compat_task()) { > - /* AArch32 uses ip (r12) for scratch */ > saved_reg = regs->regs[12]; > - regs->regs[12] = dir; > + regs->regs[12] = 0; > } 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; > + regs->regs[7] = 0; This code could also be refactored so we calculated the register number once, then avoid the if (is_compact_task()) check all over the place. Similarly on the exit path. Will
On 03/14/2014 03:41 AM, Will Deacon wrote: > On Thu, Mar 13, 2014 at 10:11:30AM +0000, AKASHI Takahiro wrote: >> 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. >> >> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> >> --- >> arch/arm64/kernel/entry.S | 10 ++++----- >> arch/arm64/kernel/ptrace.c | 48 ++++++++++++++++++++++++++++++++++---------- >> 2 files changed, 41 insertions(+), 17 deletions(-) > > [...] > >> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c >> index 6a8928b..9993a8f 100644 >> --- a/arch/arm64/kernel/ptrace.c >> +++ b/arch/arm64/kernel/ptrace.c >> @@ -1058,29 +1058,27 @@ 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) >> +asmlinkage int syscall_trace_enter(struct pt_regs *regs) >> { >> unsigned long saved_reg; >> >> if (!test_thread_flag(TIF_SYSCALL_TRACE)) >> return regs->syscallno; >> >> + /* >> + * A scrach register (ip(r12) on AArch32, x7 on AArch64) is >> + * used to denote syscall entry/exit: >> + * 0 -> entry >> + */ > > You could add an enum, like we have on ARM (ptrace_syscall_dir) for the two > directions. > >> if (is_compat_task()) { >> - /* AArch32 uses ip (r12) for scratch */ >> saved_reg = regs->regs[12]; >> - regs->regs[12] = dir; >> + regs->regs[12] = 0; >> } 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; >> + regs->regs[7] = 0; > > This code could also be refactored so we calculated the register number > once, then avoid the if (is_compact_task()) check all over the place. > > Similarly on the exit path. OK, I will implement tracehook_report_syscall() as in arm. -Takahiro AKASHI > Will >
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index f9f2cae..00d6eb9 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -649,9 +649,8 @@ 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 @@ -666,9 +665,8 @@ __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 6a8928b..9993a8f 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -1058,29 +1058,27 @@ 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) +asmlinkage int syscall_trace_enter(struct pt_regs *regs) { unsigned long saved_reg; if (!test_thread_flag(TIF_SYSCALL_TRACE)) return regs->syscallno; + /* + * A scrach register (ip(r12) on AArch32, x7 on AArch64) is + * used to denote syscall entry/exit: + * 0 -> entry + */ if (is_compat_task()) { - /* AArch32 uses ip (r12) for scratch */ saved_reg = regs->regs[12]; - regs->regs[12] = dir; + regs->regs[12] = 0; } 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; + regs->regs[7] = 0; } - if (dir) - tracehook_report_syscall_exit(regs, 0); - else if (tracehook_report_syscall_entry(regs)) + if (tracehook_report_syscall_entry(regs)) regs->syscallno = ~0UL; if (is_compat_task()) @@ -1090,3 +1088,31 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs) return regs->syscallno; } + +asmlinkage void syscall_trace_exit(struct pt_regs *regs) +{ + unsigned long saved_reg; + + if (!test_thread_flag(TIF_SYSCALL_TRACE)) + return; + + /* + * A scrach register (ip(r12) on AArch32, x7 on AArch64) is + * used to denote syscall entry/exit: + * 1 -> exit + */ + if (is_compat_task()) { + saved_reg = regs->regs[12]; + regs->regs[12] = 1; + } else { + saved_reg = regs->regs[7]; + regs->regs[7] = 1; + } + + tracehook_report_syscall_exit(regs, 0); + + if (is_compat_task()) + regs->regs[12] = saved_reg; + else + regs->regs[7] = saved_reg; +}
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. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> --- arch/arm64/kernel/entry.S | 10 ++++----- arch/arm64/kernel/ptrace.c | 48 ++++++++++++++++++++++++++++++++++---------- 2 files changed, 41 insertions(+), 17 deletions(-)