diff mbox series

[1/3] proc: Add get_task_cmdline_kernel() function

Message ID 20220801152016.36498-2-deller@gmx.de (mailing list archive)
State New, archived
Headers show
Series Dump command line of faulting process to syslog | expand

Commit Message

Helge Deller Aug. 1, 2022, 3:20 p.m. UTC 
Add a new function get_task_cmdline_kernel() which reads the command
line of a process into a kernel buffer. This command line can then be
dumped by arch code to print additional debug info on how a faulting
process was started.

The new function re-uses the existing code which provides the cmdline
for the procfs. For that the existing functions were modified so that
the buffer page is allocated outside of get_mm_proctitle() and
get_mm_cmdline() and instead provided as parameter.

Signed-off-by: Helge Deller <deller@gmx.de>
---
 fs/proc/base.c          | 68 +++++++++++++++++++++++++++--------------
 include/linux/proc_fs.h |  5 +++
 2 files changed, 50 insertions(+), 23 deletions(-)

--
2.37.1

Comments

kernel test robot Aug. 7, 2022, 2:28 p.m. UTC | #1 
Hi Helge,

I love your patch! Perhaps something to improve:

[auto build test WARNING on tip/x86/mm]
[also build test WARNING on linus/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Helge-Deller/Dump-command-line-of-faulting-process-to-syslog/20220801-232209
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 8f1d56f64f8d6b80dea2d1978d10071132a695c5
config: hexagon-randconfig-r005-20220801 (https://download.01.org/0day-ci/archive/20220807/202208072219.zrLROtui-lkp@intel.com/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 52cd00cabf479aa7eb6dbb063b7ba41ea57bce9e)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/82149c3c87cadf0a362c3015753f97c7582f31e4
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Helge-Deller/Dump-command-line-of-faulting-process-to-syslog/20220801-232209
        git checkout 82149c3c87cadf0a362c3015753f97c7582f31e4
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash kernel/sched/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from kernel/sched/core.c:84:
   In file included from kernel/sched/sched.h:50:
>> include/linux/proc_fs.h:222:64: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                  ^
   include/linux/proc_fs.h:222:72: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                          ^
   include/linux/proc_fs.h:222:80: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                                  ^
   kernel/sched/core.c:3577:20: warning: unused function 'rq_has_pinned_tasks' [-Wunused-function]
   static inline bool rq_has_pinned_tasks(struct rq *rq)
                      ^
   kernel/sched/core.c:5505:20: warning: unused function 'sched_tick_start' [-Wunused-function]
   static inline void sched_tick_start(int cpu) { }
                      ^
   kernel/sched/core.c:5506:20: warning: unused function 'sched_tick_stop' [-Wunused-function]
   static inline void sched_tick_stop(int cpu) { }
                      ^
   kernel/sched/core.c:6200:20: warning: unused function 'sched_core_cpu_starting' [-Wunused-function]
   static inline void sched_core_cpu_starting(unsigned int cpu) {}
                      ^
   kernel/sched/core.c:6201:20: warning: unused function 'sched_core_cpu_deactivate' [-Wunused-function]
   static inline void sched_core_cpu_deactivate(unsigned int cpu) {}
                      ^
   kernel/sched/core.c:6202:20: warning: unused function 'sched_core_cpu_dying' [-Wunused-function]
   static inline void sched_core_cpu_dying(unsigned int cpu) {}
                      ^
   9 warnings generated.
--
   In file included from kernel/sched/fair.c:54:
   In file included from kernel/sched/sched.h:50:
>> include/linux/proc_fs.h:222:64: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                  ^
   include/linux/proc_fs.h:222:72: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                          ^
   include/linux/proc_fs.h:222:80: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                                  ^
   kernel/sched/fair.c:5512:6: warning: no previous prototype for function 'init_cfs_bandwidth' [-Wmissing-prototypes]
   void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
        ^
   kernel/sched/fair.c:5512:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
   ^
   static 
   kernel/sched/fair.c:11697:6: warning: no previous prototype for function 'free_fair_sched_group' [-Wmissing-prototypes]
   void free_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:11697:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void free_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/fair.c:11699:5: warning: no previous prototype for function 'alloc_fair_sched_group' [-Wmissing-prototypes]
   int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
       ^
   kernel/sched/fair.c:11699:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
   ^
   static 
   kernel/sched/fair.c:11704:6: warning: no previous prototype for function 'online_fair_sched_group' [-Wmissing-prototypes]
   void online_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:11704:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void online_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/fair.c:11706:6: warning: no previous prototype for function 'unregister_fair_sched_group' [-Wmissing-prototypes]
   void unregister_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:11706:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void unregister_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/fair.c:489:20: warning: unused function 'list_del_leaf_cfs_rq' [-Wunused-function]
   static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
                      ^
   kernel/sched/fair.c:510:19: warning: unused function 'tg_is_idle' [-Wunused-function]
   static inline int tg_is_idle(struct task_group *tg)
                     ^
   kernel/sched/fair.c:2961:20: warning: unused function 'account_numa_enqueue' [-Wunused-function]
   static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p)
                      ^
   kernel/sched/fair.c:2965:20: warning: unused function 'account_numa_dequeue' [-Wunused-function]
   static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p)
                      ^
   kernel/sched/fair.c:2969:20: warning: unused function 'update_scan_period' [-Wunused-function]
   static inline void update_scan_period(struct task_struct *p, int new_cpu)
                      ^
   kernel/sched/fair.c:4171:20: warning: unused function 'cfs_rq_is_decayed' [-Wunused-function]
   static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
                      ^
   kernel/sched/fair.c:4185:20: warning: unused function 'remove_entity_load_avg' [-Wunused-function]
   static inline void remove_entity_load_avg(struct sched_entity *se) {}
                      ^
   kernel/sched/fair.c:5493:20: warning: unused function 'sync_throttle' [-Wunused-function]
   static inline void sync_throttle(struct task_group *tg, int cpu) {}
                      ^
   kernel/sched/fair.c:5506:19: warning: unused function 'throttled_lb_pair' [-Wunused-function]
   static inline int throttled_lb_pair(struct task_group *tg,
                     ^
   kernel/sched/fair.c:5518:37: warning: unused function 'tg_cfs_bandwidth' [-Wunused-function]
   static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
                                       ^
   kernel/sched/fair.c:5522:20: warning: unused function 'destroy_cfs_bandwidth' [-Wunused-function]
   static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
                      ^
   kernel/sched/fair.c:5523:20: warning: unused function 'update_runtime_enabled' [-Wunused-function]
   static inline void update_runtime_enabled(struct rq *rq) {}
                      ^
   kernel/sched/fair.c:5524:20: warning: unused function 'unthrottle_offline_cfs_rqs' [-Wunused-function]
   static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
                      ^
   21 warnings generated.
--
   In file included from kernel/sched/build_policy.c:34:
   In file included from kernel/sched/sched.h:50:
>> include/linux/proc_fs.h:222:64: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                  ^
   include/linux/proc_fs.h:222:72: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                          ^
   include/linux/proc_fs.h:222:80: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                                  ^
   In file included from kernel/sched/build_policy.c:45:
   kernel/sched/rt.c:259:6: warning: no previous prototype for function 'unregister_rt_sched_group' [-Wmissing-prototypes]
   void unregister_rt_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/rt.c:259:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void unregister_rt_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/rt.c:261:6: warning: no previous prototype for function 'free_rt_sched_group' [-Wmissing-prototypes]
   void free_rt_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/rt.c:261:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void free_rt_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/rt.c:263:5: warning: no previous prototype for function 'alloc_rt_sched_group' [-Wmissing-prototypes]
   int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
       ^
   kernel/sched/rt.c:263:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
   ^
   static 
   6 warnings generated.
--
   In file included from kernel/sched/build_utility.c:35:
>> include/linux/proc_fs.h:222:64: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                  ^
   include/linux/proc_fs.h:222:72: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                          ^
   include/linux/proc_fs.h:222:80: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
   static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
                                                                                  ^
   3 warnings generated.


vim +222 include/linux/proc_fs.h

   221	
 > 222	static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
   223
Helge Deller Aug. 7, 2022, 3:11 p.m. UTC | #2 
On 8/7/22 16:28, kernel test robot wrote:
> Hi Helge,
>
> I love your patch! Perhaps something to improve:
>
> [auto build test WARNING on tip/x86/mm]
> [also build test WARNING on linus/master]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> [...]
>    include/linux/proc_fs.h:222:72: warning: omitting the parameter name in a function definition is a C2x extension [-Wc2x-extensions]
>    static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
>                                                                           ^
Will fix.

Thanks!
Helge
diff mbox series

Patch

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8dfa36a99c74..4da9a8b3c7d1 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -217,20 +217,17 @@  static int proc_root_link(struct dentry *dentry, struct path *path)
  */
 static ssize_t get_mm_proctitle(struct mm_struct *mm, char __user *buf,
 				size_t count, unsigned long pos,
-				unsigned long arg_start)
+				unsigned long arg_start, char *page)
 {
-	char *page;
 	int ret, got;
+	size_t size;

-	if (pos >= PAGE_SIZE)
+	size = min_t(size_t, PAGE_SIZE, count);
+	if (pos >= size)
 		return 0;

-	page = (char *)__get_free_page(GFP_KERNEL);
-	if (!page)
-		return -ENOMEM;
-
 	ret = 0;
-	got = access_remote_vm(mm, arg_start, page, PAGE_SIZE, FOLL_ANON);
+	got = access_remote_vm(mm, arg_start, page, size, FOLL_ANON);
 	if (got > 0) {
 		int len = strnlen(page, got);

@@ -238,7 +235,9 @@  static ssize_t get_mm_proctitle(struct mm_struct *mm, char __user *buf,
 		if (len < got)
 			len++;

-		if (len > pos) {
+		if (!buf)
+			ret = len;
+		else if (len > pos) {
 			len -= pos;
 			if (len > count)
 				len = count;
@@ -248,16 +247,15 @@  static ssize_t get_mm_proctitle(struct mm_struct *mm, char __user *buf,
 			ret = len;
 		}
 	}
-	free_page((unsigned long)page);
 	return ret;
 }

 static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
-			      size_t count, loff_t *ppos)
+			      size_t count, loff_t *ppos, char *page)
 {
 	unsigned long arg_start, arg_end, env_start, env_end;
 	unsigned long pos, len;
-	char *page, c;
+	char c;

 	/* Check if process spawned far enough to have cmdline. */
 	if (!mm->env_end)
@@ -283,7 +281,7 @@  static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
 	len = env_end - arg_start;

 	/* We're not going to care if "*ppos" has high bits set */
-	pos = *ppos;
+	pos = ppos ? *ppos : 0;
 	if (pos >= len)
 		return 0;
 	if (count > len - pos)
@@ -299,7 +297,7 @@  static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
 	 * pos is 0, and set a flag in the 'struct file'.
 	 */
 	if (access_remote_vm(mm, arg_end-1, &c, 1, FOLL_ANON) == 1 && c)
-		return get_mm_proctitle(mm, buf, count, pos, arg_start);
+		return get_mm_proctitle(mm, buf, count, pos, arg_start, page);

 	/*
 	 * For the non-setproctitle() case we limit things strictly
@@ -311,10 +309,6 @@  static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
 	if (count > arg_end - pos)
 		count = arg_end - pos;

-	page = (char *)__get_free_page(GFP_KERNEL);
-	if (!page)
-		return -ENOMEM;
-
 	len = 0;
 	while (count) {
 		int got;
@@ -323,7 +317,8 @@  static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
 		got = access_remote_vm(mm, pos, page, size, FOLL_ANON);
 		if (got <= 0)
 			break;
-		got -= copy_to_user(buf, page, got);
+		if (buf)
+			got -= copy_to_user(buf, page, got);
 		if (unlikely(!got)) {
 			if (!len)
 				len = -EFAULT;
@@ -335,12 +330,11 @@  static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
 		count -= got;
 	}

-	free_page((unsigned long)page);
 	return len;
 }

 static ssize_t get_task_cmdline(struct task_struct *tsk, char __user *buf,
-				size_t count, loff_t *pos)
+				size_t count, loff_t *pos, char *page)
 {
 	struct mm_struct *mm;
 	ssize_t ret;
@@ -349,23 +343,51 @@  static ssize_t get_task_cmdline(struct task_struct *tsk, char __user *buf,
 	if (!mm)
 		return 0;

-	ret = get_mm_cmdline(mm, buf, count, pos);
+	ret = get_mm_cmdline(mm, buf, count, pos, page);
 	mmput(mm);
 	return ret;
 }

+/*
+ * Place up to maxcount chars of the command line of the process into the
+ * cmdline buffer.
+ */
+void get_task_cmdline_kernel(struct task_struct *tsk,
+			char *cmdline, size_t maxcount)
+{
+	int i;
+
+	memset(cmdline, 0, maxcount);
+	get_task_cmdline(tsk, NULL, maxcount - 1, NULL, cmdline);
+
+	/* remove NULs between parameters */
+	for (i = 0; i < maxcount - 2; i++) {
+		if (cmdline[i])
+			continue;
+		if (cmdline[i+1] == 0)
+			break;
+		cmdline[i] = ' ';
+	}
+}
+
 static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
 				     size_t count, loff_t *pos)
 {
 	struct task_struct *tsk;
 	ssize_t ret;
+	char *page;

 	BUG_ON(*pos < 0);

 	tsk = get_proc_task(file_inode(file));
 	if (!tsk)
 		return -ESRCH;
-	ret = get_task_cmdline(tsk, buf, count, pos);
+	page = (char *)__get_free_page(GFP_KERNEL);
+	if (page) {
+		ret = get_task_cmdline(tsk, buf, count, pos, page);
+		free_page((unsigned long)page);
+	} else
+		ret = -ENOMEM;
 	put_task_struct(tsk);
 	if (ret > 0)
 		*pos += ret;
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 81d6e4ec2294..9a256e86205c 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -158,6 +158,9 @@  int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
 			struct pid *pid, struct task_struct *task);
 #endif /* CONFIG_PROC_PID_ARCH_STATUS */

+void get_task_cmdline_kernel(struct task_struct *tsk,
+			char *cmdline, size_t maxcount);
+
 #else /* CONFIG_PROC_FS */

 static inline void proc_root_init(void)
@@ -216,6 +219,8 @@  static inline struct pid *tgid_pidfd_to_pid(const struct file *file)
 	return ERR_PTR(-EBADF);
 }

+static inline void get_task_cmdline_kernel(struct task_struct *, char *, size_t) { }
+
 #endif /* CONFIG_PROC_FS */

 struct net;