On Thu, Sep 19, 2019 at 05:03:15PM +0200, Thomas Gleixner wrote: > On syscall entry certain work needs to be done conditionally like tracing, > seccomp etc. This code is duplicated in all architectures. > > Provide a generic version. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > --- > arch/Kconfig | 3 + > include/linux/entry-common.h | 122 +++++++++++++++++++++++++++++++++++++++++++ > kernel/Makefile | 1 > kernel/entry/Makefile | 3 + > kernel/entry/common.c | 33 +++++++++++ > 5 files changed, 162 insertions(+) > > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -27,6 +27,9 @@ config HAVE_IMA_KEXEC > config HOTPLUG_SMT > bool > > +config GENERIC_ENTRY > + bool > + > config OPROFILE > tristate "OProfile system profiling" > depends on PROFILING > --- /dev/null > +++ b/include/linux/entry-common.h > @@ -0,0 +1,122 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef __LINUX_ENTRYCOMMON_H > +#define __LINUX_ENTRYCOMMON_H > + > +#include <linux/tracehook.h> > +#include <linux/syscalls.h> > +#include <linux/seccomp.h> > +#include <linux/sched.h> > +#include <linux/audit.h> > + > +#include <asm/entry-common.h> > + > +/* > + * Define dummy _TIF work flags if not defined by the architecture or for > + * disabled functionality. > + */ > +#ifndef _TIF_SYSCALL_TRACE > +# define _TIF_SYSCALL_TRACE (0) > +#endif > + > +#ifndef _TIF_SYSCALL_EMU > +# define _TIF_SYSCALL_EMU (0) > +#endif > + > +#ifndef _TIF_SYSCALL_TRACEPOINT > +# define _TIF_SYSCALL_TRACEPOINT (0) > +#endif > + > +#ifndef _TIF_SECCOMP > +# define _TIF_SECCOMP (0) > +#endif > + > +#ifndef _TIF_AUDIT > +# define _TIF_AUDIT (0) > +#endif > + > +/* > + * TIF flags handled in syscall_enter_from_usermode() > + */ > +#ifndef ARCH_SYSCALL_ENTER_WORK > +# define ARCH_SYSCALL_ENTER_WORK (0) > +#endif > + > +#define SYSCALL_ENTER_WORK \ > + (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | TIF_SECCOMP | \ > + _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU | \ > + ARCH_SYSCALL_ENTER_WORK) > + > +/** > + * arch_syscall_enter_tracehook - Wrapper around tracehook_report_syscall_entry() > + * > + * Defaults to tracehook_report_syscall_entry(). Can be replaced by > + * architecture specific code. > + * > + * Invoked from syscall_enter_from_usermode() > + */ Nit: the kernel-doc here and in other places in the patchset lacks parameter and return value descriptions, which will create lots of warnings for 'make *docs'. > +static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs); > + > +#ifndef arch_syscall_enter_tracehook > +static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs) > +{ > + return tracehook_report_syscall_entry(regs); > +} > +#endif > + > +/** > + * arch_syscall_enter_seccomp - Architecture specific seccomp invocation > + * @regs: Pointer to currents pt_regs > + * > + * Invoked from syscall_enter_from_usermode(). Can be replaced by > + * architecture specific code. > + */ > +static inline long arch_syscall_enter_seccomp(struct pt_regs *regs); > + > +#ifndef arch_syscall_enter_seccomp > +static inline long arch_syscall_enter_seccomp(struct pt_regs *regs) > +{ > + return secure_computing(NULL); > +} > +#endif > + > +/** > + * arch_syscall_enter_audit - Architecture specific audit invocation > + * @regs: Pointer to currents pt_regs > + * > + * Invoked from syscall_enter_from_usermode(). Must be replaced by > + * architecture specific code if the architecture supports audit. > + */ > +static inline void arch_syscall_enter_audit(struct pt_regs *regs); > + > +#ifndef arch_syscall_enter_audit > +static inline void arch_syscall_enter_audit(struct pt_regs *regs) { } > +#endif > + > +/* Common syscall enter function */ > +long core_syscall_enter_from_usermode(struct pt_regs *regs, long syscall); > + > +/** > + * syscall_enter_from_usermode - Check and handle work before invoking > + * a syscall > + * @regs: Pointer to currents pt_regs > + * @syscall: The syscall number > + * > + * Invoked from architecture specific syscall entry code with interrupts > + * enabled. > + * > + * Returns: The original or a modified syscall number > + */ > +static inline long syscall_enter_from_usermode(struct pt_regs *regs, > + long syscall) > +{ > + unsigned long ti_work = READ_ONCE(current_thread_info()->flags); > + > + if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) > + BUG_ON(regs != task_pt_regs(current)); > + > + if (ti_work & SYSCALL_ENTER_WORK) > + syscall = core_syscall_enter_from_usermode(regs, syscall); > + return syscall; > +} > + > +#endif > --- a/kernel/Makefile > +++ b/kernel/Makefile > @@ -43,6 +43,7 @@ obj-y += irq/ > obj-y += rcu/ > obj-y += livepatch/ > obj-y += dma/ > +obj-y += entry/ > > obj-$(CONFIG_CHECKPOINT_RESTORE) += kcmp.o > obj-$(CONFIG_FREEZER) += freezer.o > --- /dev/null > +++ b/kernel/entry/Makefile > @@ -0,0 +1,3 @@ > +# SPDX-License-Identifier: GPL-2.0 > + > +obj-$(CONFIG_GENERIC_ENTRY) += common.o > --- /dev/null > +++ b/kernel/entry/common.c > @@ -0,0 +1,33 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include <linux/context_tracking.h> > +#include <linux/entry-common.h> > + > +#define CREATE_TRACE_POINTS > +#include <trace/events/syscalls.h> > + > +long core_syscall_enter_from_usermode(struct pt_regs *regs, long syscall) > +{ > + unsigned long ti_work = READ_ONCE(current_thread_info()->flags); > + unsigned long ret = 0; > + > + if (ti_work & (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU)) { > + ret = arch_syscall_enter_tracehook(regs); > + if (ret || (ti_work & _TIF_SYSCALL_EMU)) > + return -1L; > + } > + > + /* Do seccomp after ptrace, to catch any tracer changes. */ > + if (ti_work & _TIF_SECCOMP) { > + ret = arch_syscall_enter_seccomp(regs); > + if (ret == -1L) > + return ret; > + } > + > + if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT))) > + trace_sys_enter(regs, syscall); > + > + arch_syscall_enter_audit(regs); > + > + return ret ? : syscall; > +} > > -- Sincerely yours, Mike.