The patch titled
tracehook: asm/syscall.h
has been added to the -mm tree. Its filename is
tracehook-asm-syscallh.patch
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------------------------------------------------------
Subject: tracehook: asm/syscall.h
From: Roland McGrath <roland@xxxxxxxxxx>
This adds asm-generic/syscall.h, which documents what a real
asm-ARCH/syscall.h file should define. This is not used yet, but will
provide all the machine-dependent details of examining a user system call
about to begin, in progress, or just ended.
Each arch should add an asm-ARCH/syscall.h that defines all the entry
points documented in asm-generic/syscall.h, as short inlines if possible.
This lets us write new tracing code that understands user system call
registers, without any new arch-specific work.
Signed-off-by: Roland McGrath <roland@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-generic/syscall.h | 141 ++++++++++++++++++++++++++++++++
include/linux/tracehook.h | 3
2 files changed, 143 insertions(+), 1 deletion(-)
diff -puN /dev/null include/asm-generic/syscall.h
--- /dev/null
+++ a/include/asm-generic/syscall.h
@@ -0,0 +1,141 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License v.2.
+ *
+ * This file is a stub providing documentation for what functions
+ * asm-ARCH/syscall.h files need to define. Most arch definitions
+ * will be simple inlines.
+ *
+ * All of these functions expect to be called with no locks,
+ * and only when the caller is sure that the task of interest
+ * cannot return to user mode while we are looking at it.
+ */
+
+#ifndef _ASM_SYSCALL_H
+#define _ASM_SYSCALL_H 1
+
+struct task_struct;
+struct pt_regs;
+
+/**
+ * syscall_get_nr - find what system call a task is executing
+ * @task: task of interest, must be blocked
+ * @regs: task_pt_regs() of @task
+ *
+ * If @task is executing a system call or is at system call
+ * tracing about to attempt one, returns the system call number.
+ * If @task is not executing a system call, i.e. it's blocked
+ * inside the kernel for a fault or signal, returns -1.
+ *
+ * It's only valid to call this when @task is known to be blocked.
+ */
+long syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
+
+/**
+ * syscall_rollback - roll back registers after an aborted system call
+ * @task: task of interest, must be in system call exit tracing
+ * @regs: task_pt_regs() of @task
+ *
+ * It's only valid to call this when @task is stopped for system
+ * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
+ * after tracehook_report_syscall_entry() returned nonzero to prevent
+ * the system call from taking place.
+ *
+ * This rolls back the register state in @regs so it's as if the
+ * system call instruction was a no-op. The registers containing
+ * the system call number and arguments are as they were before the
+ * system call instruction. This may not be the same as what the
+ * register state looked like at system call entry tracing.
+ */
+void syscall_rollback(struct task_struct *task, struct pt_regs *regs);
+
+/**
+ * syscall_get_error - check result of traced system call
+ * @task: task of interest, must be blocked
+ * @regs: task_pt_regs() of @task
+ *
+ * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
+ *
+ * It's only valid to call this when @task is stopped for tracing on exit
+ * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ */
+long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
+
+/**
+ * syscall_get_return_value - get the return value of a traced system call
+ * @task: task of interest, must be blocked
+ * @regs: task_pt_regs() of @task
+ *
+ * Returns the return value of the successful system call.
+ * This value is meaningless if syscall_get_error() returned nonzero.
+ *
+ * It's only valid to call this when @task is stopped for tracing on exit
+ * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ */
+long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
+
+/**
+ * syscall_set_return_value - change the return value of a traced system call
+ * @task: task of interest, must be blocked
+ * @regs: task_pt_regs() of @task
+ * @error: negative error code, or zero to indicate success
+ * @val: user return value if @error is zero
+ *
+ * This changes the results of the system call that user mode will see.
+ * If @error is zero, the user sees a successful system call with a
+ * return value of @val. If @error is nonzero, it's a negated errno
+ * code; the user sees a failed system call with this errno code.
+ *
+ * It's only valid to call this when @task is stopped for tracing on exit
+ * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ */
+void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
+ int error, long val);
+
+/**
+ * syscall_get_arguments - extract system call parameter values
+ * @task: task of interest, must be blocked
+ * @regs: task_pt_regs() of @task
+ * @i: argument index [0,5]
+ * @n: number of arguments; n+i must be [1,6].
+ * @args: array filled with argument values
+ *
+ * Fetches @n arguments to the system call starting with the @i'th argument
+ * (from 0 through 5). Argument @i is stored in @args[0], and so on.
+ * An arch inline version is probably optimal when @i and @n are constants.
+ *
+ * It's only valid to call this when @task is stopped for tracing on
+ * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * It's invalid to call this with @i + @n > 6; we only support system calls
+ * taking up to 6 arguments.
+ */
+void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
+ unsigned int i, unsigned int n, unsigned long *args);
+
+/**
+ * syscall_set_arguments - change system call parameter value
+ * @task: task of interest, must be in system call entry tracing
+ * @regs: task_pt_regs() of @task
+ * @i: argument index [0,5]
+ * @n: number of arguments; n+i must be [1,6].
+ * @args: array of argument values to store
+ *
+ * Changes @n arguments to the system call starting with the @i'th argument.
+ * @n'th argument to @val. Argument @i gets value @args[0], and so on.
+ * An arch inline version is probably optimal when @i and @n are constants.
+ *
+ * It's only valid to call this when @task is stopped for tracing on
+ * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * It's invalid to call this with @i + @n > 6; we only support system calls
+ * taking up to 6 arguments.
+ */
+void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
+ unsigned int i, unsigned int n,
+ const unsigned long *args);
+
+#endif /* _ASM_SYSCALL_H */
diff -puN include/linux/tracehook.h~tracehook-asm-syscallh include/linux/tracehook.h
--- a/include/linux/tracehook.h~tracehook-asm-syscallh
+++ a/include/linux/tracehook.h
@@ -103,7 +103,8 @@ static inline void ptrace_report_syscall
* the system call. That must prevent normal entry so no system call is
* made. If @task ever returns to user mode after this, its register state
* is unspecified, but should be something harmless like an %ENOSYS error
- * return.
+ * return. It should preserve enough information so that syscall_rollback()
+ * can work (see asm-generic/syscall.h).
*
* Called without locks, just after entering kernel mode.
*/
_
Patches currently in -mm which might be from roland@xxxxxxxxxx are
origin.patch
execve-filename-document-and-export-via-auxiliary-vector.patch
flag-parameters-paccept-fix.patch
flag-parameters-paccept-fix-flag-parameters-arch-specific-sock_nonblock.patch
posix-timers-timer_delete-remove-the-bogus-it_process-=-null-check.patch
posix-timers-release_posix_timer-kill-the-bogus-put_task_struct-it_process.patch
signals-collect_signal-remove-the-unneeded-sigismember-check.patch
signals-collect_signal-simplify-the-still_pending-logic.patch
__exit_signal-dont-take-rcu-lock.patch
signals-dequeue_signal-dont-check-signal_group_exit-when-setting-signal_stop_dequeued.patch
signals-do_signal_stop-kill-the-signal_unkillable-check.patch
coredump-zap_threads-comments-use-while_each_thread.patch
signals-make-siginfo_t-si_utime-si_sstime-report-times-in-user_hz-not-hz.patch
kernel-signalc-change-vars-pid-and-tgid-types-to-pid_t.patch
include-asm-ptraceh-userspace-headers-cleanup.patch
ptrace-give-more-respect-to-sigkill.patch
ptrace-simplify-ptrace_stop-sigkill_pending-path.patch
ptrace-do_wait-reorganization.patch
ptrace-ptrace-children-revamp.patch
ptrace-do_wait-return-security_task_wait-error-code-in-place-of-echild.patch
ptrace-fix-dangling-zombie-when-new-parent-ignores-children.patch
introduce-pf_kthread-flag.patch
kill-pf_borrowed_mm-in-favour-of-pf_kthread.patch
coredump-zap_threads-must-skip-kernel-threads.patch
coredump-elf_core_dump-skip-kernel-threads.patch
coredump-turn-mm-core_startup_done-into-the-pointer-to-struct-core_state.patch
coredump-move-mm-core_waiters-into-struct-core_state.patch
coredump-simplify-core_state-nr_threads-calculation.patch
coredump-turn-core_state-nr_threads-into-atomic_t.patch
coredump-make-mm-core_state-visible-to-core_dump.patch
coredump-construct-the-list-of-coredumping-threads-at-startup-time.patch
coredump-elf_core_dump-use-core_state-dumper-list.patch
coredump-elf_fdpic_core_dump-use-core_state-dumper-list.patch
coredump-kill-mm-core_done.patch
coredump-binfmt_elf_fdpic-dont-use-sub-threads-mm.patch
coredump-exit_mm-clear-mm-first-then-play-with-core_state.patch
coredump-exit_mm-clear-mm-first-then-play-with-core_state-checkpatch-fixes.patch
tracehook-add-linux-tracehookh.patch
tracehook-exec.patch
tracehook-unexport-ptrace_notify.patch
tracehook-exit.patch
tracehook-clone.patch
tracehook-vfork-done.patch
tracehook-release_task.patch
tracehook-tracehook_tracer_task.patch
tracehook-tracehook_expect_breakpoints.patch
tracehook-tracehook_signal_handler.patch
tracehook-tracehook_consider_ignored_signal.patch
tracehook-tracehook_consider_fatal_signal.patch
tracehook-syscall.patch
tracehook-get_signal_to_deliver.patch
tracehook-job-control.patch
tracehook-death.patch
tracehook-force-signal_pending.patch
tracehook-tif_notify_resume.patch
tracehook-asm-syscallh.patch
tracehook-config_have_arch_tracehook.patch
tracehook-wait_task_inactive.patch
task_current_syscall.patch
proc-pid-syscall.patch
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