Re: [PATCH v2 06/13] parisc: use generic sys_fanotify_mark implementation

On Mon, Jun 24, 2024 at 06:37:04PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
> 
> The sys_fanotify_mark() syscall on parisc uses the reverse word order
> for the two halves of the 64-bit argument compared to all syscalls on
> all 32-bit architectures. As far as I can tell, the problem is that
> the function arguments on parisc are sorted backwards (26, 25, 24, 23,
> ...) compared to everyone else, so the calling conventions of using an
> even/odd register pair in native word order result in the lower word
> coming first in function arguments, matching the expected behavior
> on little-endian architectures. The system call conventions however
> ended up matching what the other 32-bit architectures do.
> 
> A glibc cleanup in 2020 changed the userspace behavior in a way that
> handles all architectures consistently, but this inadvertently broke
> parisc32 by changing to the same method as everyone else.
> 
> The change made it into glibc-2.35 and subsequently into debian 12
> (bookworm), which is the latest stable release. This means we
> need to choose between reverting the glibc change or changing the
> kernel to match it again, but either hange will leave some systems
> broken.
> 
> Pick the option that is more likely to help current and future
> users and change the kernel to match current glibc. This also
> means the behavior is now consistent across architectures, but
> it breaks running new kernels with old glibc builds before 2.35.
> 
> Link: https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=d150181d73d9
> Link: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/arch/parisc/kernel/sys_parisc.c?h=57b1dfbd5b4a39d
> Cc: Adhemerval Zanella <[email protected]>
> Tested-by: Helge Deller <[email protected]>
> Acked-by: Helge Deller <[email protected]>
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> I found this through code inspection, please double-check to make
> sure I got the bug and the fix right.
> 

Building parisc:allmodconfig ... failed
--------------
Error log:
In file included from fs/notify/fanotify/fanotify_user.c:14:
include/linux/syscalls.h:248:25: error: conflicting types for 'sys_fanotify_mark'; have 'long int(int,  unsigned int,  u32,  u32,  int,  const char *)' {aka 'long int(int,  unsigned int,  unsigned int,  unsigned int,  int,  const char *)'}
  248 |         asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))       \
      |                         ^~~
include/linux/syscalls.h:234:9: note: in expansion of macro '__SYSCALL_DEFINEx'
  234 |         __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
      |         ^~~~~~~~~~~~~~~~~
include/linux/syscalls.h:228:36: note: in expansion of macro 'SYSCALL_DEFINEx'
  228 | #define SYSCALL_DEFINE6(name, ...) SYSCALL_DEFINEx(6, _##name, __VA_ARGS__)
      |                                    ^~~~~~~~~~~~~~~
include/linux/syscalls.h:287:27: note: in expansion of macro 'SYSCALL_DEFINE6'
  287 | #define SYSCALL32_DEFINE6 SYSCALL_DEFINE6
      |                           ^~~~~~~~~~~~~~~
fs/notify/fanotify/fanotify_user.c:1924:1: note: in expansion of macro 'SYSCALL32_DEFINE6'
 1924 | SYSCALL32_DEFINE6(fanotify_mark,
      | ^~~~~~~~~~~~~~~~~
include/linux/syscalls.h:862:17: note: previous declaration of 'sys_fanotify_mark' with type 'long int(int,  unsigned int,  u64,  int,  const char *)' {aka 'long int(int,  unsigned int,  long long unsigned int,  int,  const char *)'}
  862 | asmlinkage long sys_fanotify_mark(int fanotify_fd, unsigned int flags,
      |                 ^~~~~~~~~~~~~~~~~
make[6]: [scripts/Makefile.build:244: fs/notify/fanotify/fanotify_user.o] Error 1 (ignored)

Guenter