[PATCH 1/1 fyi] tools include UAPI: Sync linux/fcntl.h copy with the kernel sources

[PATCH 1/1 fyi] tools include UAPI: Sync linux/fcntl.h copy with the kernel sources

[Arnaldo Carvalho de Melo]

Picking the changes from:

  4356d575ef0f39a3 ("fhandle: expose u64 mount id to name_to_handle_at(2)")
  b4fef22c2fb97fa2 ("uapi: explain how per-syscall AT_* flags should be allocated")
  820a185896b77814 ("fcntl: add F_CREATED_QUERY")

It just moves AT_REMOVEDIR around, and adds a bunch more AT_ for
renameat2() and name_to_handle_at(). We need to improve this situation,
as not all AT_ defines are applicable to all fs flags...

This adds support for those new AT_ defines, addressing this build
warning:

  diff -u tools/perf/trace/beauty/include/uapi/sound/asound.h include/uapi/sound/asound.h

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/lkml/
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/trace/beauty/fs_at_flags.sh        |  5 ++
 .../trace/beauty/include/uapi/linux/fcntl.h   | 84 +++++++++++++------
 2 files changed, 65 insertions(+), 24 deletions(-)

diff --git a/tools/perf/trace/beauty/fs_at_flags.sh b/tools/perf/trace/beauty/fs_at_flags.sh
index 456f59addf741062..e3f13f96a27c227c 100755
--- a/tools/perf/trace/beauty/fs_at_flags.sh
+++ b/tools/perf/trace/beauty/fs_at_flags.sh
@@ -13,9 +13,14 @@ printf "static const char *fs_at_flags[] = {\n"
 regex='^[[:space:]]*#[[:space:]]*define[[:space:]]+AT_([^_]+[[:alnum:]_]+)[[:space:]]+(0x[[:xdigit:]]+)[[:space:]]*.*'
 # AT_EACCESS is only meaningful to faccessat, so we will special case it there...
 # AT_STATX_SYNC_TYPE is not a bit, its a mask of AT_STATX_SYNC_AS_STAT, AT_STATX_FORCE_SYNC and AT_STATX_DONT_SYNC
+# AT_HANDLE_FID and AT_HANDLE_MNT_ID_UNIQUE are reusing values and are valid only for name_to_handle_at()
+# AT_RENAME_NOREPLACE reuses 0x1 and is valid only for renameat2()
 grep -E $regex ${linux_fcntl} | \
 	grep -v AT_EACCESS | \
 	grep -v AT_STATX_SYNC_TYPE | \
+	grep -v AT_HANDLE_FID | \
+	grep -v AT_HANDLE_MNT_ID_UNIQUE | \
+	grep -v AT_RENAME_NOREPLACE | \
 	sed -r "s/$regex/\2 \1/g"	| \
 	xargs printf "\t[ilog2(%s) + 1] = \"%s\",\n"
 printf "};\n"
diff --git a/tools/perf/trace/beauty/include/uapi/linux/fcntl.h b/tools/perf/trace/beauty/include/uapi/linux/fcntl.h
index c0bcc185fa48f852..87e2dec79fea4ef2 100644
--- a/tools/perf/trace/beauty/include/uapi/linux/fcntl.h
+++ b/tools/perf/trace/beauty/include/uapi/linux/fcntl.h
@@ -16,6 +16,9 @@
 
 #define F_DUPFD_QUERY	(F_LINUX_SPECIFIC_BASE + 3)
 
+/* Was the file just created? */
+#define F_CREATED_QUERY	(F_LINUX_SPECIFIC_BASE + 4)
+
 /*
  * Cancel a blocking posix lock; internal use only until we expose an
  * asynchronous lock api to userspace:
@@ -87,37 +90,70 @@
 #define DN_ATTRIB	0x00000020	/* File changed attibutes */
 #define DN_MULTISHOT	0x80000000	/* Don't remove notifier */
 
+#define AT_FDCWD		-100    /* Special value for dirfd used to
+					   indicate openat should use the
+					   current working directory. */
+
+
+/* Generic flags for the *at(2) family of syscalls. */
+
+/* Reserved for per-syscall flags	0xff. */
+#define AT_SYMLINK_NOFOLLOW		0x100   /* Do not follow symbolic
+						   links. */
+/* Reserved for per-syscall flags	0x200 */
+#define AT_SYMLINK_FOLLOW		0x400   /* Follow symbolic links. */
+#define AT_NO_AUTOMOUNT			0x800	/* Suppress terminal automount
+						   traversal. */
+#define AT_EMPTY_PATH			0x1000	/* Allow empty relative
+						   pathname to operate on dirfd
+						   directly. */
+/*
+ * These flags are currently statx(2)-specific, but they could be made generic
+ * in the future and so they should not be used for other per-syscall flags.
+ */
+#define AT_STATX_SYNC_TYPE		0x6000	/* Type of synchronisation required from statx() */
+#define AT_STATX_SYNC_AS_STAT		0x0000	/* - Do whatever stat() does */
+#define AT_STATX_FORCE_SYNC		0x2000	/* - Force the attributes to be sync'd with the server */
+#define AT_STATX_DONT_SYNC		0x4000	/* - Don't sync attributes with the server */
+
+#define AT_RECURSIVE			0x8000	/* Apply to the entire subtree */
+
 /*
- * The constants AT_REMOVEDIR and AT_EACCESS have the same value.  AT_EACCESS is
- * meaningful only to faccessat, while AT_REMOVEDIR is meaningful only to
- * unlinkat.  The two functions do completely different things and therefore,
- * the flags can be allowed to overlap.  For example, passing AT_REMOVEDIR to
- * faccessat would be undefined behavior and thus treating it equivalent to
- * AT_EACCESS is valid undefined behavior.
+ * Per-syscall flags for the *at(2) family of syscalls.
+ *
+ * These are flags that are so syscall-specific that a user passing these flags
+ * to the wrong syscall is so "clearly wrong" that we can safely call such
+ * usage "undefined behaviour".
+ *
+ * For example, the constants AT_REMOVEDIR and AT_EACCESS have the same value.
+ * AT_EACCESS is meaningful only to faccessat, while AT_REMOVEDIR is meaningful
+ * only to unlinkat. The two functions do completely different things and
+ * therefore, the flags can be allowed to overlap. For example, passing
+ * AT_REMOVEDIR to faccessat would be undefined behavior and thus treating it
+ * equivalent to AT_EACCESS is valid undefined behavior.
+ *
+ * Note for implementers: When picking a new per-syscall AT_* flag, try to
+ * reuse already existing flags first. This leaves us with as many unused bits
+ * as possible, so we can use them for generic bits in the future if necessary.
  */
-#define AT_FDCWD		-100    /* Special value used to indicate
-                                           openat should use the current
-                                           working directory. */
-#define AT_SYMLINK_NOFOLLOW	0x100   /* Do not follow symbolic links.  */
+
+/* Flags for renameat2(2) (must match legacy RENAME_* flags). */
+#define AT_RENAME_NOREPLACE	0x0001
+#define AT_RENAME_EXCHANGE	0x0002
+#define AT_RENAME_WHITEOUT	0x0004
+
+/* Flag for faccessat(2). */
 #define AT_EACCESS		0x200	/* Test access permitted for
                                            effective IDs, not real IDs.  */
+/* Flag for unlinkat(2). */
 #define AT_REMOVEDIR		0x200   /* Remove directory instead of
                                            unlinking file.  */
-#define AT_SYMLINK_FOLLOW	0x400   /* Follow symbolic links.  */
-#define AT_NO_AUTOMOUNT		0x800	/* Suppress terminal automount traversal */
-#define AT_EMPTY_PATH		0x1000	/* Allow empty relative pathname */
-
-#define AT_STATX_SYNC_TYPE	0x6000	/* Type of synchronisation required from statx() */
-#define AT_STATX_SYNC_AS_STAT	0x0000	/* - Do whatever stat() does */
-#define AT_STATX_FORCE_SYNC	0x2000	/* - Force the attributes to be sync'd with the server */
-#define AT_STATX_DONT_SYNC	0x4000	/* - Don't sync attributes with the server */
-
-#define AT_RECURSIVE		0x8000	/* Apply to the entire subtree */
+/* Flags for name_to_handle_at(2). */
+#define AT_HANDLE_FID		0x200	/* File handle is needed to compare
+					   object identity and may not be
+					   usable with open_by_handle_at(2). */
+#define AT_HANDLE_MNT_ID_UNIQUE	0x001	/* Return the u64 unique mount ID. */
 
-/* Flags for name_to_handle_at(2). We reuse AT_ flag space to save bits... */
-#define AT_HANDLE_FID		AT_REMOVEDIR	/* file handle is needed to
-					compare object identity and may not
-					be usable to open_by_handle_at(2) */
 #if defined(__KERNEL__)
 #define AT_GETATTR_NOSEC	0x80000000
 #endif
-- 
2.46.0

Re: [PATCH 1/1 fyi] tools include UAPI: Sync linux/fcntl.h copy with the kernel sources

[Aleksa Sarai]

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On 2024-09-30, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> Picking the changes from:
> 
>   4356d575ef0f39a3 ("fhandle: expose u64 mount id to name_to_handle_at(2)")
>   b4fef22c2fb97fa2 ("uapi: explain how per-syscall AT_* flags should be allocated")
>   820a185896b77814 ("fcntl: add F_CREATED_QUERY")
> 
> It just moves AT_REMOVEDIR around, and adds a bunch more AT_ for
> renameat2() and name_to_handle_at(). We need to improve this situation,
> as not all AT_ defines are applicable to all fs flags...
> 
> This adds support for those new AT_ defines, addressing this build
> warning:
> 
>   diff -u tools/perf/trace/beauty/include/uapi/sound/asound.h include/uapi/sound/asound.h

Thanks, feel free to take my

Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>

> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Aleksa Sarai <cyphar@cyphar.com>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Ian Rogers <irogers@google.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Tejun Heo <tj@kernel.org>
> Link: https://lore.kernel.org/lkml/
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
>  tools/perf/trace/beauty/fs_at_flags.sh        |  5 ++
>  .../trace/beauty/include/uapi/linux/fcntl.h   | 84 +++++++++++++------
>  2 files changed, 65 insertions(+), 24 deletions(-)
> 
> diff --git a/tools/perf/trace/beauty/fs_at_flags.sh b/tools/perf/trace/beauty/fs_at_flags.sh
> index 456f59addf741062..e3f13f96a27c227c 100755
> --- a/tools/perf/trace/beauty/fs_at_flags.sh
> +++ b/tools/perf/trace/beauty/fs_at_flags.sh
> @@ -13,9 +13,14 @@ printf "static const char *fs_at_flags[] = {\n"
>  regex='^[[:space:]]*#[[:space:]]*define[[:space:]]+AT_([^_]+[[:alnum:]_]+)[[:space:]]+(0x[[:xdigit:]]+)[[:space:]]*.*'
>  # AT_EACCESS is only meaningful to faccessat, so we will special case it there...
>  # AT_STATX_SYNC_TYPE is not a bit, its a mask of AT_STATX_SYNC_AS_STAT, AT_STATX_FORCE_SYNC and AT_STATX_DONT_SYNC
> +# AT_HANDLE_FID and AT_HANDLE_MNT_ID_UNIQUE are reusing values and are valid only for name_to_handle_at()
> +# AT_RENAME_NOREPLACE reuses 0x1 and is valid only for renameat2()
>  grep -E $regex ${linux_fcntl} | \
>  	grep -v AT_EACCESS | \
>  	grep -v AT_STATX_SYNC_TYPE | \
> +	grep -v AT_HANDLE_FID | \
> +	grep -v AT_HANDLE_MNT_ID_UNIQUE | \
> +	grep -v AT_RENAME_NOREPLACE | \
>  	sed -r "s/$regex/\2 \1/g"	| \
>  	xargs printf "\t[ilog2(%s) + 1] = \"%s\",\n"
>  printf "};\n"
> diff --git a/tools/perf/trace/beauty/include/uapi/linux/fcntl.h b/tools/perf/trace/beauty/include/uapi/linux/fcntl.h
> index c0bcc185fa48f852..87e2dec79fea4ef2 100644
> --- a/tools/perf/trace/beauty/include/uapi/linux/fcntl.h
> +++ b/tools/perf/trace/beauty/include/uapi/linux/fcntl.h
> @@ -16,6 +16,9 @@
>  
>  #define F_DUPFD_QUERY	(F_LINUX_SPECIFIC_BASE + 3)
>  
> +/* Was the file just created? */
> +#define F_CREATED_QUERY	(F_LINUX_SPECIFIC_BASE + 4)
> +
>  /*
>   * Cancel a blocking posix lock; internal use only until we expose an
>   * asynchronous lock api to userspace:
> @@ -87,37 +90,70 @@
>  #define DN_ATTRIB	0x00000020	/* File changed attibutes */
>  #define DN_MULTISHOT	0x80000000	/* Don't remove notifier */
>  
> +#define AT_FDCWD		-100    /* Special value for dirfd used to
> +					   indicate openat should use the
> +					   current working directory. */
> +
> +
> +/* Generic flags for the *at(2) family of syscalls. */
> +
> +/* Reserved for per-syscall flags	0xff. */
> +#define AT_SYMLINK_NOFOLLOW		0x100   /* Do not follow symbolic
> +						   links. */
> +/* Reserved for per-syscall flags	0x200 */
> +#define AT_SYMLINK_FOLLOW		0x400   /* Follow symbolic links. */
> +#define AT_NO_AUTOMOUNT			0x800	/* Suppress terminal automount
> +						   traversal. */
> +#define AT_EMPTY_PATH			0x1000	/* Allow empty relative
> +						   pathname to operate on dirfd
> +						   directly. */
> +/*
> + * These flags are currently statx(2)-specific, but they could be made generic
> + * in the future and so they should not be used for other per-syscall flags.
> + */
> +#define AT_STATX_SYNC_TYPE		0x6000	/* Type of synchronisation required from statx() */
> +#define AT_STATX_SYNC_AS_STAT		0x0000	/* - Do whatever stat() does */
> +#define AT_STATX_FORCE_SYNC		0x2000	/* - Force the attributes to be sync'd with the server */
> +#define AT_STATX_DONT_SYNC		0x4000	/* - Don't sync attributes with the server */
> +
> +#define AT_RECURSIVE			0x8000	/* Apply to the entire subtree */
> +
>  /*
> - * The constants AT_REMOVEDIR and AT_EACCESS have the same value.  AT_EACCESS is
> - * meaningful only to faccessat, while AT_REMOVEDIR is meaningful only to
> - * unlinkat.  The two functions do completely different things and therefore,
> - * the flags can be allowed to overlap.  For example, passing AT_REMOVEDIR to
> - * faccessat would be undefined behavior and thus treating it equivalent to
> - * AT_EACCESS is valid undefined behavior.
> + * Per-syscall flags for the *at(2) family of syscalls.
> + *
> + * These are flags that are so syscall-specific that a user passing these flags
> + * to the wrong syscall is so "clearly wrong" that we can safely call such
> + * usage "undefined behaviour".
> + *
> + * For example, the constants AT_REMOVEDIR and AT_EACCESS have the same value.
> + * AT_EACCESS is meaningful only to faccessat, while AT_REMOVEDIR is meaningful
> + * only to unlinkat. The two functions do completely different things and
> + * therefore, the flags can be allowed to overlap. For example, passing
> + * AT_REMOVEDIR to faccessat would be undefined behavior and thus treating it
> + * equivalent to AT_EACCESS is valid undefined behavior.
> + *
> + * Note for implementers: When picking a new per-syscall AT_* flag, try to
> + * reuse already existing flags first. This leaves us with as many unused bits
> + * as possible, so we can use them for generic bits in the future if necessary.
>   */
> -#define AT_FDCWD		-100    /* Special value used to indicate
> -                                           openat should use the current
> -                                           working directory. */
> -#define AT_SYMLINK_NOFOLLOW	0x100   /* Do not follow symbolic links.  */
> +
> +/* Flags for renameat2(2) (must match legacy RENAME_* flags). */
> +#define AT_RENAME_NOREPLACE	0x0001
> +#define AT_RENAME_EXCHANGE	0x0002
> +#define AT_RENAME_WHITEOUT	0x0004
> +
> +/* Flag for faccessat(2). */
>  #define AT_EACCESS		0x200	/* Test access permitted for
>                                             effective IDs, not real IDs.  */
> +/* Flag for unlinkat(2). */
>  #define AT_REMOVEDIR		0x200   /* Remove directory instead of
>                                             unlinking file.  */
> -#define AT_SYMLINK_FOLLOW	0x400   /* Follow symbolic links.  */
> -#define AT_NO_AUTOMOUNT		0x800	/* Suppress terminal automount traversal */
> -#define AT_EMPTY_PATH		0x1000	/* Allow empty relative pathname */
> -
> -#define AT_STATX_SYNC_TYPE	0x6000	/* Type of synchronisation required from statx() */
> -#define AT_STATX_SYNC_AS_STAT	0x0000	/* - Do whatever stat() does */
> -#define AT_STATX_FORCE_SYNC	0x2000	/* - Force the attributes to be sync'd with the server */
> -#define AT_STATX_DONT_SYNC	0x4000	/* - Don't sync attributes with the server */
> -
> -#define AT_RECURSIVE		0x8000	/* Apply to the entire subtree */
> +/* Flags for name_to_handle_at(2). */
> +#define AT_HANDLE_FID		0x200	/* File handle is needed to compare
> +					   object identity and may not be
> +					   usable with open_by_handle_at(2). */
> +#define AT_HANDLE_MNT_ID_UNIQUE	0x001	/* Return the u64 unique mount ID. */
>  
> -/* Flags for name_to_handle_at(2). We reuse AT_ flag space to save bits... */
> -#define AT_HANDLE_FID		AT_REMOVEDIR	/* file handle is needed to
> -					compare object identity and may not
> -					be usable to open_by_handle_at(2) */
>  #if defined(__KERNEL__)
>  #define AT_GETATTR_NOSEC	0x80000000
>  #endif
> -- 
> 2.46.0
> 

-- 
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>

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Re: [PATCH 1/1 fyi] tools include UAPI: Sync linux/fcntl.h copy with the kernel sources

[Arnaldo Carvalho de Melo]

On Mon, Sep 30, 2024 at 06:24:50PM +0200, Aleksa Sarai wrote:
> On 2024-09-30, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> > Picking the changes from:
> > 
> >   4356d575ef0f39a3 ("fhandle: expose u64 mount id to name_to_handle_at(2)")
> >   b4fef22c2fb97fa2 ("uapi: explain how per-syscall AT_* flags should be allocated")
> >   820a185896b77814 ("fcntl: add F_CREATED_QUERY")
> > 
> > It just moves AT_REMOVEDIR around, and adds a bunch more AT_ for
> > renameat2() and name_to_handle_at(). We need to improve this situation,
> > as not all AT_ defines are applicable to all fs flags...
> > 
> > This adds support for those new AT_ defines, addressing this build
> > warning:
> > 
> >   diff -u tools/perf/trace/beauty/include/uapi/sound/asound.h include/uapi/sound/asound.h
> 
> Thanks, feel free to take my
> 
> Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>

Thanks, added.

- Arnaldo