linux/io_uring
Rick Edgecombe 529ce23a76 mm: switch mm->get_unmapped_area() to a flag
The mm_struct contains a function pointer *get_unmapped_area(), which is
set to either arch_get_unmapped_area() or arch_get_unmapped_area_topdown()
during the initialization of the mm.

Since the function pointer only ever points to two functions that are
named the same across all arch's, a function pointer is not really
required.  In addition future changes will want to add versions of the
functions that take additional arguments.  So to save a pointers worth of
bytes in mm_struct, and prevent adding additional function pointers to
mm_struct in future changes, remove it and keep the information about
which get_unmapped_area() to use in a flag.

Add the new flag to MMF_INIT_MASK so it doesn't get clobbered on fork by
mmf_init_flags().  Most MM flags get clobbered on fork.  In the
pre-existing behavior mm->get_unmapped_area() would get copied to the new
mm in dup_mm(), so not clobbering the flag preserves the existing behavior
around inheriting the topdown-ness.

Introduce a helper, mm_get_unmapped_area(), to easily convert code that
refers to the old function pointer to instead select and call either
arch_get_unmapped_area() or arch_get_unmapped_area_topdown() based on the
flag.  Then drop the mm->get_unmapped_area() function pointer.  Leave the
get_unmapped_area() pointer in struct file_operations alone.  The main
purpose of this change is to reorganize in preparation for future changes,
but it also converts the calls of mm->get_unmapped_area() from indirect
branches into a direct ones.

The stress-ng bigheap benchmark calls realloc a lot, which calls through
get_unmapped_area() in the kernel.  On x86, the change yielded a ~1%
improvement there on a retpoline config.

In testing a few x86 configs, removing the pointer unfortunately didn't
result in any actual size reductions in the compiled layout of mm_struct. 
But depending on compiler or arch alignment requirements, the change could
shrink the size of mm_struct.

Link: https://lkml.kernel.org/r/20240326021656.202649-3-rick.p.edgecombe@intel.com
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: H. Peter Anvin (Intel) <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25 20:56:25 -07:00
..
advise.c io_uring: always go async for unsupported fadvise flags 2023-01-29 15:18:26 -07:00
advise.h
alloc_cache.h io_uring: use mempool KASAN hook 2023-12-29 11:58:41 -08:00
cancel.c io_uring/cancel: don't default to setting req->work.cancel_seq 2024-02-08 13:27:06 -07:00
cancel.h io_uring/cancel: don't default to setting req->work.cancel_seq 2024-02-08 13:27:06 -07:00
epoll.c io_uring: undeprecate epoll_ctl support 2023-05-26 20:22:41 -06:00
epoll.h
fdinfo.c io_uring: Fix sqpoll utilization check racing with dying sqpoll 2024-03-09 07:27:09 -07:00
fdinfo.h
filetable.c io_uring: drop any code related to SCM_RIGHTS 2023-12-19 12:36:34 -07:00
filetable.h io_uring: expand main struct io_kiocb flags to 64-bits 2024-02-08 13:27:03 -07:00
fs.c io_uring/fs: consider link->flags when getting path for LINKAT 2023-11-20 09:01:42 -07:00
fs.h
futex.c io_uring/futex: always remove futex entry for cancel all 2024-03-15 15:37:15 -06:00
futex.h io_uring: add support for vectored futex waits 2023-09-29 02:37:08 -06:00
io_uring.c mm: switch mm->get_unmapped_area() to a flag 2024-04-25 20:56:25 -07:00
io_uring.h io_uring/napi: ensure napi polling is aborted when work is available 2024-02-14 13:01:25 -07:00
io-wq.c io-wq: fully initialize wqe before calling cpuhp_state_add_instance_nocalls() 2023-10-05 14:11:18 -06:00
io-wq.h io_uring: break out of iowq iopoll on teardown 2023-09-07 09:02:27 -06:00
kbuf.c io_uring/kbuf: hold io_buffer_list reference over mmap 2024-04-02 19:03:27 -06:00
kbuf.h io_uring/kbuf: hold io_buffer_list reference over mmap 2024-04-02 19:03:27 -06:00
Makefile io-uring: add napi busy poll support 2024-02-09 11:54:19 -07:00
msg_ring.c io_uring: use io_file_from_index in io_msg_grab_file 2023-06-20 09:36:22 -06:00
msg_ring.h io_uring: get rid of double locking 2022-12-07 06:47:13 -07:00
napi.c io_uring/napi: enable even with a timeout of 0 2024-02-15 15:37:28 -07:00
napi.h io_uring: add register/unregister napi function 2024-02-09 11:54:32 -07:00
net.c io_uring/net: restore msg_control on sendzc retry 2024-04-08 21:48:41 -06:00
net.h io_uring: Add KASAN support for alloc_caches 2023-04-03 07:16:14 -06:00
nop.c
nop.h
notif.c io_uring/notif: add constant for ubuf_info flags 2023-04-15 14:21:04 -06:00
notif.h io_uring/notif: add constant for ubuf_info flags 2023-04-15 14:21:04 -06:00
opdef.c io_uring: add support for ftruncate 2024-02-09 09:04:39 -07:00
opdef.h io_uring/rw: mark readv/writev as vectored in the opcode definition 2023-09-21 12:00:46 -06:00
openclose.c io_uring: enable audit and restrict cred override for IORING_OP_FIXED_FD_INSTALL 2024-01-23 15:25:14 -07:00
openclose.h io_uring/openclose: add support for IORING_OP_FIXED_FD_INSTALL 2023-12-12 07:42:57 -07:00
poll.c io_uring: fix poll_remove stalled req completion 2024-03-15 09:36:56 -06:00
poll.h io_uring/rw: ensure poll based multishot read retries appropriately 2024-01-28 20:37:11 -07:00
refs.h
register.c io_uring: add register/unregister napi function 2024-02-09 11:54:32 -07:00
register.h io_uring/register: move io_uring_register(2) related code to register.c 2023-12-19 08:54:20 -07:00
rsrc.c io_uring: drop any code related to SCM_RIGHTS 2023-12-19 12:36:34 -07:00
rsrc.h io_uring: Don't include af_unix.h. 2024-02-12 19:02:11 -07:00
rw.c io_uring/rw: don't allow multishot reads without NOWAIT support 2024-04-01 11:41:50 -06:00
rw.h io_uring/rw: add separate prep handler for fixed read/write 2023-11-06 07:43:16 -07:00
slist.h io_uring: silence variable ‘prev’ set but not used warning 2023-03-09 10:10:58 -07:00
splice.c splice: return type ssize_t from all helpers 2023-12-12 16:19:59 +01:00
splice.h
sqpoll.c io_uring/sqpoll: early exit thread if task_context wasn't allocated 2024-03-18 20:22:42 -06:00
sqpoll.h io_uring/sqpoll: statistics of the true utilization of sq threads 2024-03-01 06:28:19 -07:00
statx.c io_uring: for requests that require async, force it 2023-01-29 15:18:26 -07:00
statx.h
sync.c io_uring: for requests that require async, force it 2023-01-29 15:18:26 -07:00
sync.h
tctx.c io_uring: Add io_uring_setup flag to pre-register ring fd and never install it 2023-05-16 08:06:00 -06:00
tctx.h io_uring: simplify __io_uring_add_tctx_node 2022-10-07 12:25:30 -06:00
timeout.c io_uring: never overflow io_aux_cqe 2023-08-11 10:42:57 -06:00
timeout.h io_uring: remove unused return from io_disarm_next 2022-09-21 13:15:01 -06:00
truncate.c io_uring: add support for ftruncate 2024-02-09 09:04:39 -07:00
truncate.h io_uring: add support for ftruncate 2024-02-09 09:04:39 -07:00
uring_cmd.c io_uring: Don't include af_unix.h. 2024-02-12 19:02:11 -07:00
uring_cmd.h io_uring: Remove unnecessary BUILD_BUG_ON 2023-05-04 08:19:05 -06:00
waitid.c io_uring/waitid: always remove waitid entry for cancel all 2024-03-15 15:42:49 -06:00
waitid.h io_uring: add IORING_OP_WAITID support 2023-09-21 12:04:45 -06:00
xattr.c io_uring: use file_mnt_idmap helper 2024-02-06 19:55:14 -07:00
xattr.h