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Or, it might be okay to give a hint to wrong process). This patch aims for supporting both options like waitid(2). So, the syscall is currently, int process_madvise(int which, pid_t pid, void *addr, size_t length, int advise, unsigned long flag); @which is actually idtype_t for userspace libray and currently, it supports P_PID and P_PIDFD. [1] https://lore.kernel.org/linux-mm/9d849087-3359-c4ab-fbec-859e8186c509@virtuozzo.com/ Signed-off-by: Minchan Kim --- include/linux/pid.h | 1 + include/linux/syscalls.h | 3 ++- kernel/exit.c | 17 ----------------- kernel/pid.c | 17 +++++++++++++++++ mm/madvise.c | 34 ++++++++++++++++++++++------------ 5 files changed, 42 insertions(+), 30 deletions(-) diff --git a/include/linux/pid.h b/include/linux/pid.h index 998ae7d24450..023d9c3a8edc 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -75,6 +75,7 @@ extern const struct file_operations pidfd_fops; struct file; extern struct pid *pidfd_pid(const struct file *file); +extern struct pid *pidfd_get_pid(unsigned int fd); static inline struct pid *get_pid(struct pid *pid) { diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 1b58a11ff49f..27060e59db37 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -877,7 +877,8 @@ asmlinkage long sys_munlockall(void); asmlinkage long sys_mincore(unsigned long start, size_t len, unsigned char __user * vec); asmlinkage long sys_madvise(unsigned long start, size_t len, int behavior); -asmlinkage long sys_process_madvise(int pidfd, unsigned long start, + +asmlinkage long sys_process_madvise(int which, pid_t pid, unsigned long start, size_t len, int behavior, unsigned long flags); asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size, unsigned long prot, unsigned long pgoff, diff --git a/kernel/exit.c b/kernel/exit.c index bcbd59888e67..7698843b1411 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1466,23 +1466,6 @@ static long do_wait(struct wait_opts *wo) return retval; } -static struct pid *pidfd_get_pid(unsigned int fd) -{ - struct fd f; - struct pid *pid; - - f = fdget(fd); - if (!f.file) - return ERR_PTR(-EBADF); - - pid = pidfd_pid(f.file); - if (!IS_ERR(pid)) - get_pid(pid); - - fdput(f); - return pid; -} - static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, int options, struct rusage *ru) { diff --git a/kernel/pid.c b/kernel/pid.c index 2278e249141d..a41a89d5dad2 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -496,6 +496,23 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns) return idr_get_next(&ns->idr, &nr); } +struct pid *pidfd_get_pid(unsigned int fd) +{ + struct fd f; + struct pid *pid; + + f = fdget(fd); + if (!f.file) + return ERR_PTR(-EBADF); + + pid = pidfd_pid(f.file); + if (!IS_ERR(pid)) + get_pid(pid); + + fdput(f); + return pid; +} + /** * pidfd_create() - Create a new pid file descriptor. * diff --git a/mm/madvise.c b/mm/madvise.c index 39c40cbb389e..ba3a9bd8ea27 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1197,11 +1197,10 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) return madvise_common(current, current->mm, start, len_in, behavior); } -SYSCALL_DEFINE5(process_madvise, int, pidfd, unsigned long, start, +SYSCALL_DEFINE6(process_madvise, int, which, pid_t, upid, unsigned long, start, size_t, len_in, int, behavior, unsigned long, flags) { int ret; - struct fd f; struct pid *pid; struct task_struct *task; struct mm_struct *mm; @@ -1212,20 +1211,31 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, unsigned long, start, if (!process_madvise_behavior_valid(behavior)) return -EINVAL; - f = fdget(pidfd); - if (!f.file) - return -EBADF; + switch (which) { + case P_PID: + if (upid <= 0) + return -EINVAL; + + pid = find_get_pid(upid); + if (!pid) + return -ESRCH; + break; + case P_PIDFD: + if (upid < 0) + return -EINVAL; - pid = pidfd_pid(f.file); - if (IS_ERR(pid)) { - ret = PTR_ERR(pid); - goto fdput; + pid = pidfd_get_pid(upid); + if (IS_ERR(pid)) + return PTR_ERR(pid); + break; + default: + return -EINVAL; } task = get_pid_task(pid, PIDTYPE_PID); if (!task) { ret = -ESRCH; - goto fdput; + goto put_pid; } mm = mm_access(task, PTRACE_MODE_ATTACH_FSCREDS); @@ -1238,7 +1248,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, unsigned long, start, mmput(mm); release_task: put_task_struct(task); -fdput: - fdput(f); +put_pid: + put_pid(pid); return ret; }