| Message ID | 20190318104925.16600-3-sudeep.holla@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | ptrace: consolidate PTRACE_SYSEMU handling and add support for arm64 | expand |
On Mon, Mar 18, 2019 at 10:49:21AM +0000, Sudeep Holla wrote: > Currently each architecture handles PTRACE_SYSEMU in very similar way. > It's completely arch independent and can be handled in the code helping > to consolidate PTRACE_SYSEMU handling. > > Let's introduce a hook 'ptrace_syscall_enter' that arch specific syscall > entry code can call. > > Cc: Oleg Nesterov <oleg@redhat.com> > Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> > --- > include/linux/ptrace.h | 1 + > kernel/ptrace.c | 22 ++++++++++++++++++++++ > 2 files changed, 23 insertions(+) > > diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h > index edb9b040c94c..e30f51e3363e 100644 > --- a/include/linux/ptrace.h > +++ b/include/linux/ptrace.h > @@ -407,6 +407,7 @@ static inline void user_single_step_report(struct pt_regs *regs) > #define current_user_stack_pointer() user_stack_pointer(current_pt_regs()) > #endif > > +extern long ptrace_syscall_enter(struct pt_regs *regs); > extern int task_current_syscall(struct task_struct *target, long *callno, > unsigned long args[6], unsigned int maxargs, > unsigned long *sp, unsigned long *pc); > diff --git a/kernel/ptrace.c b/kernel/ptrace.c > index 4fa3b7f4c3c7..c9c505c483df 100644 > --- a/kernel/ptrace.c > +++ b/kernel/ptrace.c > @@ -29,6 +29,7 @@ > #include <linux/hw_breakpoint.h> > #include <linux/cn_proc.h> > #include <linux/compat.h> > +#include <linux/tracehook.h> > > /* > * Access another process' address space via ptrace. > @@ -557,6 +558,27 @@ static int ptrace_detach(struct task_struct *child, unsigned int data) > return 0; > } > > +/* > + * Hook to check and report for PTRACE_SYSEMU, can be called from arch > + * arch syscall entry code > + */ > +long ptrace_syscall_enter(struct pt_regs *regs) > +{ > +#ifdef TIF_SYSCALL_EMU > + if (test_thread_flag(TIF_SYSCALL_EMU)) { > + if (tracehook_report_syscall_entry(regs)) > + /* > + * We can ignore the return code here as we need > + * return -1 always for syscall emulation irrespective > + * of whether the tracehook report fails or succeed. > + */ > + ; This is problematic as it causes build errors with -Werror=empty-body, see https://lore.kernel.org/lkml/20181218205305.26647-1-malat@debian.org/ -- ldv
On Mon, Mar 18, 2019 at 10:49:21AM +0000, Sudeep Holla wrote: > Currently each architecture handles PTRACE_SYSEMU in very similar way. > It's completely arch independent and can be handled in the code helping > to consolidate PTRACE_SYSEMU handling. > > Let's introduce a hook 'ptrace_syscall_enter' that arch specific syscall > entry code can call. Sorry if I'm late for the party, but the new name looks confusing. If all it does is related to TIF_SYSCALL_EMU, why does it have a generic name 'ptrace_syscall_enter' without any hint of being specific to TIF_SYSCALL_EMU? -- ldv
On Mon, Mar 18, 2019 at 05:31:47PM +0300, Dmitry V. Levin wrote: > On Mon, Mar 18, 2019 at 10:49:21AM +0000, Sudeep Holla wrote: > > Currently each architecture handles PTRACE_SYSEMU in very similar way. > > It's completely arch independent and can be handled in the code helping > > to consolidate PTRACE_SYSEMU handling. > > > > Let's introduce a hook 'ptrace_syscall_enter' that arch specific syscall > > entry code can call. > > > > Cc: Oleg Nesterov <oleg@redhat.com> > > Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> > > --- > > include/linux/ptrace.h | 1 + > > kernel/ptrace.c | 22 ++++++++++++++++++++++ > > 2 files changed, 23 insertions(+) > > > > diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h > > index edb9b040c94c..e30f51e3363e 100644 > > --- a/include/linux/ptrace.h > > +++ b/include/linux/ptrace.h > > @@ -407,6 +407,7 @@ static inline void user_single_step_report(struct pt_regs *regs) > > #define current_user_stack_pointer() user_stack_pointer(current_pt_regs()) > > #endif > > > > +extern long ptrace_syscall_enter(struct pt_regs *regs); > > extern int task_current_syscall(struct task_struct *target, long *callno, > > unsigned long args[6], unsigned int maxargs, > > unsigned long *sp, unsigned long *pc); > > diff --git a/kernel/ptrace.c b/kernel/ptrace.c > > index 4fa3b7f4c3c7..c9c505c483df 100644 > > --- a/kernel/ptrace.c > > +++ b/kernel/ptrace.c > > @@ -29,6 +29,7 @@ > > #include <linux/hw_breakpoint.h> > > #include <linux/cn_proc.h> > > #include <linux/compat.h> > > +#include <linux/tracehook.h> > > > > /* > > * Access another process' address space via ptrace. > > @@ -557,6 +558,27 @@ static int ptrace_detach(struct task_struct *child, unsigned int data) > > return 0; > > } > > > > +/* > > + * Hook to check and report for PTRACE_SYSEMU, can be called from arch > > + * arch syscall entry code > > + */ > > +long ptrace_syscall_enter(struct pt_regs *regs) > > +{ > > +#ifdef TIF_SYSCALL_EMU > > + if (test_thread_flag(TIF_SYSCALL_EMU)) { > > + if (tracehook_report_syscall_entry(regs)) > > + /* > > + * We can ignore the return code here as we need > > + * return -1 always for syscall emulation irrespective > > + * of whether the tracehook report fails or succeed. > > + */ > > + ; > > This is problematic as it causes build errors with -Werror=empty-body, > see https://lore.kernel.org/lkml/20181218205305.26647-1-malat@debian.org/ > Thanks for the pointer, will update. -- Regards, Sudeep
On Mon, Mar 18, 2019 at 05:41:15PM +0300, Dmitry V. Levin wrote: > On Mon, Mar 18, 2019 at 10:49:21AM +0000, Sudeep Holla wrote: > > Currently each architecture handles PTRACE_SYSEMU in very similar way. > > It's completely arch independent and can be handled in the code helping > > to consolidate PTRACE_SYSEMU handling. > > > > Let's introduce a hook 'ptrace_syscall_enter' that arch specific syscall > > entry code can call. > > Sorry if I'm late for the party, but the new name looks confusing. > If all it does is related to TIF_SYSCALL_EMU, why does it have a generic > name 'ptrace_syscall_enter' without any hint of being specific to > TIF_SYSCALL_EMU? > Not at all late. Infact Haibo Xu pointed that out, I updated but somehow missed to commit and lost those changes. I will rename as ptrace_sysemu_syscall_enter -- Regards, Sudeep
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index edb9b040c94c..e30f51e3363e 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -407,6 +407,7 @@ static inline void user_single_step_report(struct pt_regs *regs) #define current_user_stack_pointer() user_stack_pointer(current_pt_regs()) #endif +extern long ptrace_syscall_enter(struct pt_regs *regs); extern int task_current_syscall(struct task_struct *target, long *callno, unsigned long args[6], unsigned int maxargs, unsigned long *sp, unsigned long *pc); diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 4fa3b7f4c3c7..c9c505c483df 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -29,6 +29,7 @@ #include <linux/hw_breakpoint.h> #include <linux/cn_proc.h> #include <linux/compat.h> +#include <linux/tracehook.h> /* * Access another process' address space via ptrace. @@ -557,6 +558,27 @@ static int ptrace_detach(struct task_struct *child, unsigned int data) return 0; } +/* + * Hook to check and report for PTRACE_SYSEMU, can be called from arch + * arch syscall entry code + */ +long ptrace_syscall_enter(struct pt_regs *regs) +{ +#ifdef TIF_SYSCALL_EMU + if (test_thread_flag(TIF_SYSCALL_EMU)) { + if (tracehook_report_syscall_entry(regs)) + /* + * We can ignore the return code here as we need + * return -1 always for syscall emulation irrespective + * of whether the tracehook report fails or succeed. + */ + ; + return -1L; + } +#endif + return 0; +} + /* * Detach all tasks we were using ptrace on. Called with tasklist held * for writing.
Currently each architecture handles PTRACE_SYSEMU in very similar way. It's completely arch independent and can be handled in the code helping to consolidate PTRACE_SYSEMU handling. Let's introduce a hook 'ptrace_syscall_enter' that arch specific syscall entry code can call. Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> --- include/linux/ptrace.h | 1 + kernel/ptrace.c | 22 ++++++++++++++++++++++ 2 files changed, 23 insertions(+) -- 2.17.1