In do_notify_resume(), call task_isolation_ready() when we are checking the thread-info flags; and after we've handled the other work, call task_isolation_enter() unconditionally. To ensure we always call task_isolation_enter() when returning to userspace, modify _TIF_WORK_MASK to be _TIF_NOHZ, which is set in every task, when we build with TASK_ISOLATION configured.
We tweak syscall_trace_enter() slightly to carry the "flags" value from current_thread_info()->flags for each of the tests, rather than doing a volatile read from memory for each one. This avoids a small overhead for each test, and in particular avoids that overhead for TIF_NOHZ when TASK_ISOLATION is not enabled. We instrument the smp_cross_call() routine so that it checks for isolated tasks and generates a suitable warning if we are about to disturb one of them in strict or debug mode. Finally, add an explicit check for STRICT mode in do_mem_abort() to handle the case of page faults. Signed-off-by: Chris Metcalf <[email protected]> --- arch/arm64/include/asm/thread_info.h | 8 +++++++- arch/arm64/kernel/ptrace.c | 12 +++++++++--- arch/arm64/kernel/signal.c | 6 +++++- arch/arm64/kernel/smp.c | 2 ++ arch/arm64/mm/fault.c | 4 ++++ 5 files changed, 27 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index abd64bd1f6d9..89c72888cb54 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -131,9 +131,15 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_SECCOMP (1 << TIF_SECCOMP) #define _TIF_32BIT (1 << TIF_32BIT) -#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ +#define _TIF_WORK_LOOP_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE) +#ifdef CONFIG_TASK_ISOLATION +# define _TIF_WORK_MASK _TIF_NOHZ /* always set */ +#else +# define _TIF_WORK_MASK _TIF_WORK_LOOP_MASK +#endif + #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \ _TIF_NOHZ) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index ff7f13239515..43aa6d016f46 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -37,6 +37,7 @@ #include <linux/regset.h> #include <linux/tracehook.h> #include <linux/elf.h> +#include <linux/isolation.h> #include <asm/compat.h> #include <asm/debug-monitors.h> @@ -1246,14 +1247,19 @@ static void tracehook_report_syscall(struct pt_regs *regs, asmlinkage int syscall_trace_enter(struct pt_regs *regs) { - /* Do the secure computing check first; failures should be fast. */ + unsigned long work = ACCESS_ONCE(current_thread_info()->flags); + + if ((work & _TIF_NOHZ) && task_isolation_check_syscall(regs->syscallno)) + return -1; + + /* Do the secure computing check early; failures should be fast. */ if (secure_computing() == -1) return -1; - if (test_thread_flag(TIF_SYSCALL_TRACE)) + if (work & _TIF_SYSCALL_TRACE) tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER); - if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) + if (work & _TIF_SYSCALL_TRACEPOINT) trace_sys_enter(regs, regs->syscallno); audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1], diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index 3432e14b7d6e..53fcd6c305d6 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -25,6 +25,7 @@ #include <linux/uaccess.h> #include <linux/tracehook.h> #include <linux/ratelimit.h> +#include <linux/isolation.h> #include <asm/debug-monitors.h> #include <asm/elf.h> @@ -419,12 +420,15 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, if (thread_flags & _TIF_FOREIGN_FPSTATE) fpsimd_restore_current_state(); + + task_isolation_enter(); } local_irq_disable(); thread_flags = READ_ONCE(current_thread_info()->flags); - if (!(thread_flags & _TIF_WORK_MASK)) + if (!(thread_flags & _TIF_WORK_LOOP_MASK) && + task_isolation_ready()) break; } } diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index b1adc51b2c2e..dcb3282d04a2 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -37,6 +37,7 @@ #include <linux/completion.h> #include <linux/of.h> #include <linux/irq_work.h> +#include <linux/isolation.h> #include <asm/alternative.h> #include <asm/atomic.h> @@ -632,6 +633,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = { static void smp_cross_call(const struct cpumask *target, unsigned int ipinr) { trace_ipi_raise(target, ipi_types[ipinr]); + task_isolation_debug_cpumask(target); __smp_cross_call(target, ipinr); } diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index abe2a9542b3a..644cd634dd1d 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -29,6 +29,7 @@ #include <linux/sched.h> #include <linux/highmem.h> #include <linux/perf_event.h> +#include <linux/isolation.h> #include <asm/cpufeature.h> #include <asm/exception.h> @@ -473,6 +474,9 @@ asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr, const struct fault_info *inf = fault_info + (esr & 63); struct siginfo info; + if (user_mode(regs)) + task_isolation_check_exception("%s at %#lx", inf->name, addr); + if (!inf->fn(addr, esr, regs)) return; -- 2.1.2
