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Linus Torvalds 1bd4403d86 unsafe_[get|put]_user: change interface to use a error target label 
When I initially added the unsafe_[get|put]_user() helpers in commit
5b24a7a2aa ("Add 'unsafe' user access functions for batched
accesses"), I made the mistake of modeling the interface on our
traditional __[get|put]_user() functions, which return zero on success,
or -EFAULT on failure.

That interface is fairly easy to use, but it's actually fairly nasty for
good code generation, since it essentially forces the caller to check
the error value for each access.

In particular, since the error handling is already internally
implemented with an exception handler, and we already use "asm goto" for
various other things, we could fairly easily make the error cases just
jump directly to an error label instead, and avoid the need for explicit
checking after each operation.

So switch the interface to pass in an error label, rather than checking
the error value in the caller.  Best do it now before we start growing
more users (the signal handling code in particular would be a good place
to use the new interface).

So rather than

	if (unsafe_get_user(x, ptr))
		... handle error ..

the interface is now

	unsafe_get_user(x, ptr, label);

where an error during the user mode fetch will now just cause a jump to
'label' in the caller.

Right now the actual _implementation_ of this all still ends up being a
"if (err) goto label", and does not take advantage of any exception
label tricks, but for "unsafe_put_user()" in particular it should be
fairly straightforward to convert to using the exception table model.

Note that "unsafe_get_user()" is much harder to convert to a clever
exception table model, because current versions of gcc do not allow the
use of "asm goto" (for the exception) with output values (for the actual
value to be fetched).  But that is hopefully not a limitation in the
long term.

[ Also note that it might be a good idea to switch unsafe_get_user() to
  actually _return_ the value it fetches from user space, but this
  commit only changes the error handling semantics ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-08 13:02:01 -07:00
..
842 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2016-03-17 21:38:27 -07:00
fonts
lz4 lib: lz4: cleanup unaligned access efficiency detection 2016-04-13 09:22:49 -07:00
lzo
mpi lib/mpi: Fix SG miter leak 2016-07-29 18:30:16 +08:00
raid6 powerpc: Create disable_kernel_{fp,altivec,vsx,spe}() 2015-12-01 13:52:25 +11:00
reed_solomon
xz
zlib_deflate
zlib_inflate
.gitignore
argv_split.c
asn1_decoder.c Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-05-17 09:33:39 -07:00
assoc_array.c assoc_array: don't call compare_object() on a node 2016-04-06 14:06:48 +01:00
atomic64_test.c locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() 2016-06-16 10:48:32 +02:00
atomic64.c locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() 2016-06-16 10:48:32 +02:00
audit.c
bcd.c
bch.c
bitmap.c x86/uaccess: Move thread_info::addr_limit to thread_struct 2016-07-15 10:26:30 +02:00
bitrev.c
bsearch.c
btree.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
bug.c lib/bug.c: use common WARN helper 2016-03-17 15:09:34 -07:00
build_OID_registry
bust_spinlocks.c
chacha20.c random: replace non-blocking pool with a Chacha20-based CRNG 2016-07-03 00:57:23 -04:00
check_signature.c
checksum.c ipv4: Update parameters for csum_tcpudp_magic to their original types 2016-03-13 23:55:13 -04:00
clz_ctz.c
clz_tab.c
cmdline.c
compat_audit.c
cordic.c
cpu_rmap.c
cpu-notifier-error-inject.c
cpumask.c cpumask: Export cpumask_any_but() 2016-02-29 09:35:20 +01:00
crc7.c
crc8.c
crc16.c
crc32.c crc32: use ktime_get_ns() for measurement 2016-08-02 19:35:08 -04:00
crc32defs.h
crc-ccitt.c
crc-itu-t.c
crc-t10dif.c
ctype.c
debug_info.c
debug_locks.c
debugobjects.c debugobjects: insulate non-fixup logic related to static obj from fixup callbacks 2016-05-19 19:12:14 -07:00
dec_and_lock.c
decompress_bunzip2.c
decompress_inflate.c
decompress_unlz4.c
decompress_unlzma.c
decompress_unlzo.c
decompress_unxz.c
decompress.c
devres.c devres: use to_pci_dev() 2016-02-07 23:17:59 -08:00
digsig.c lib/digsig: digsig_verify_rsa(): return -EINVAL if modulo length is zero 2016-05-31 16:42:00 +08:00
div64.c __div64_32(): make it overridable at compile time 2015-11-16 14:42:12 -05:00
dma-debug.c dma-debug: track bucket lock state for static checkers 2016-07-26 16:19:19 -07:00
dma-noop.c dma-mapping: use unsigned long for dma_attrs 2016-08-04 08:50:07 -04:00
dump_stack.c dump_stack: avoid potential deadlocks 2016-02-05 18:10:40 -08:00
dynamic_debug.c dynamic_debug: add jump label support 2016-08-04 08:50:07 -04:00
dynamic_queue_limits.c
earlycpio.c lib/cpio: Make find_cpio_data()'s offset arg optional 2016-06-08 11:04:19 +02:00
extable.c extable: add support for relative extables to search and sort routines 2016-02-24 14:57:26 +00:00
fault-inject.c fault-inject: fix inverted interval/probability values in printk 2015-10-23 17:55:10 +09:00
fdt_empty_tree.c
fdt_ro.c
fdt_rw.c
fdt_strerror.c
fdt_sw.c
fdt_wip.c
fdt.c
find_bit.c
flex_array.c
flex_proportions.c lib+mm: fix few spelling mistakes 2016-02-15 11:18:23 +01:00
gcd.c lib/GCD.c: use binary GCD algorithm instead of Euclidean 2016-05-20 17:58:30 -07:00
gen_crc32table.c
genalloc.c CPM/QE: use genalloc to manage CPM/QE muram 2015-12-22 17:10:18 -06:00
glob.c
halfmd4.c lib/halfmd4.c: use rol32 inline function in the ROUND macro 2015-11-06 17:50:42 -08:00
hexdump.c lib/hexdump.c: truncate output in case of overflow 2015-11-06 17:50:42 -08:00
hweight.c x86/hweight: Get rid of the special calling convention 2016-06-08 15:01:02 +02:00
idr.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
inflate.c
int_sqrt.c
interval_tree_test.c
interval_tree.c
iomap_copy.c lib/iomap_copy.c: add __ioread32_copy() 2016-01-20 17:09:18 -08:00
iomap.c
iommu-common.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2015-11-05 16:34:48 -08:00
iommu-helper.c lib/iommu-helper: skip to next segment 2016-08-02 19:35:07 -04:00
ioremap.c
iov_iter.c mm: optimize copy_page_to/from_iter_iovec 2016-07-28 16:07:41 -07:00
irq_poll.c irq_poll: Fix irq_poll_sched() 2016-01-19 15:26:55 -05:00
irq_regs.c
is_single_threaded.c lib/is_single_threaded.c: change current_is_single_threaded() to use for_each_thread() 2015-11-06 17:50:42 -08:00
jedec_ddr_data.c
kasprintf.c lib/kasprintf.c: add sanity check to kvasprintf 2016-01-16 11:17:27 -08:00
Kconfig raxix-tree: introduce CONFIG_RADIX_TREE_MULTIORDER 2016-05-20 17:58:30 -07:00
Kconfig.debug Merge branch 'akpm' (patches from Andrew) 2016-08-02 21:08:07 -04:00
Kconfig.kasan mm, kasan: switch SLUB to stackdepot, enable memory quarantine for SLUB 2016-07-28 16:07:41 -07:00
Kconfig.kgdb kgdb: depends on VT 2016-05-23 17:04:14 -07:00
Kconfig.kmemcheck
Kconfig.ubsan ubsan: fix tree-wide -Wmaybe-uninitialized false positives 2016-03-22 15:36:02 -07:00
kfifo.c
klist.c klist: fix starting point removed bug in klist iterators 2016-02-07 22:18:47 -08:00
kobject_uevent.c
kobject.c kobject: export kset_find_obj() for module use 2016-02-09 17:36:34 -08:00
kstrtox.c lib: add "on"/"off" support to kstrtobool 2016-03-17 15:09:34 -07:00
kstrtox.h
lcm.c
libcrc32c.c Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-01-22 11:58:43 -08:00
list_debug.c list: kill list_force_poison() 2016-03-09 15:43:42 -08:00
list_sort.c
llist.c lib/llist.c: fix data race in llist_del_first 2015-11-06 17:50:42 -08:00
locking-selftest-hardirq.h
locking-selftest-mutex.h
locking-selftest-rlock-hardirq.h
locking-selftest-rlock-softirq.h
locking-selftest-rlock.h
locking-selftest-rsem.h
locking-selftest-softirq.h
locking-selftest-spin-hardirq.h
locking-selftest-spin-softirq.h
locking-selftest-spin.h
locking-selftest-wlock-hardirq.h
locking-selftest-wlock-softirq.h
locking-selftest-wlock.h
locking-selftest-wsem.h
locking-selftest.c
lockref.c
lru_cache.c lru_cache: Converted lc_seq_printf_status to return void 2015-11-25 09:22:02 -07:00
Makefile A number of improvements for the /dev/random driver; the most 2016-07-27 15:11:55 -07:00
md5.c
memory-notifier-error-inject.c
memweight.c
net_utils.c
netdev-notifier-error-inject.c net: Add support for CHANGEUPPER notifier error injection 2015-12-03 11:49:23 -05:00
nlattr.c libnl: fix help of _64bit functions 2016-04-23 20:13:24 -04:00
nmi_backtrace.c printk/nmi: generic solution for safe printk in NMI 2016-05-20 17:58:30 -07:00
nodemask.c include/linux/nodemask.h: create next_node_in() helper 2016-05-19 19:12:14 -07:00
notifier-error-inject.c
notifier-error-inject.h
of-reconfig-notifier-error-inject.c
oid_registry.c
once.c once: make helper generic for calling functions once 2015-10-08 05:26:36 -07:00
parser.c
pci_iomap.c
percpu_counter.c percpu_counter: update debugobjects fixup callbacks return type 2016-05-19 19:12:14 -07:00
percpu_ida.c mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM 2015-11-06 17:50:42 -08:00
percpu_test.c
percpu-refcount.c lib+mm: fix few spelling mistakes 2016-02-15 11:18:23 +01:00
plist.c
pm-notifier-error-inject.c
radix-tree.c radix-tree: account nodes to memcg only if explicitly requested 2016-08-02 17:31:41 -04:00
random32.c timers: Remove set_timer_slack() leftovers 2016-07-07 10:35:09 +02:00
ratelimit.c ratelimit: extend to print suppressed messages on release 2016-08-02 19:35:06 -04:00
rational.c
rbtree_test.c
rbtree.c Introduce rb_replace_node_rcu() 2016-07-06 10:51:14 +01:00
reciprocal_div.c
rhashtable.c rhashtable: accept GFP flags in rhashtable_walk_init 2016-04-05 10:56:32 +02:00
scatterlist.c scatterlist: fix a typo in comment block of sg_miter_stop() 2016-02-08 10:15:17 -08:00
seq_buf.c tracing: Use seq_buf_used() in seq_buf_to_user() instead of len 2015-12-23 14:27:20 -05:00
sg_pool.c lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c 2016-04-15 16:53:14 -04:00
sg_split.c
sha1.c lib: EXPORT_SYMBOL sha_init 2015-03-23 22:12:08 -04:00
show_mem.c
smp_processor_id.c
sort.c
stackdepot.c lib/stackdepot.c: use __GFP_NOWARN for stack allocations 2016-07-28 16:07:41 -07:00
stmp_device.c
string_helpers.c string_helpers: add kstrdup_quotable_file 2016-04-21 10:47:26 +10:00
string.c lib: move strtobool() to kstrtobool() 2016-03-17 15:09:34 -07:00
strncpy_from_user.c unsafe_[get|put]_user: change interface to use a error target label 2016-08-08 13:02:01 -07:00
strnlen_user.c unsafe_[get|put]_user: change interface to use a error target label 2016-08-08 13:02:01 -07:00
swiotlb.c dma-mapping: use unsigned long for dma_attrs 2016-08-04 08:50:07 -04:00
syscall.c
test_bitmap.c test_bitmap: unit tests for lib/bitmap.c 2016-02-19 22:54:09 -05:00
test_bpf.c bpf: prepare bpf_int_jit_compile/bpf_prog_select_runtime apis 2016-05-16 13:49:32 -04:00
test_firmware.c test: firmware_class: add asynchronous request trigger 2016-01-07 13:44:22 -07:00
test_hash.c vfs: make the string hashes salt the hash 2016-06-10 20:21:46 -07:00
test_hexdump.c test_hexdump: print statistics at the end 2016-01-20 17:09:18 -08:00
test_kasan.c kasan/tests: add tests for user memory access functions 2016-05-20 17:58:30 -07:00
test_module.c
test_printf.c mm, printk: introduce new format string for flags 2016-03-15 16:55:16 -07:00
test_rhashtable.c rhashtable: accept GFP flags in rhashtable_walk_init 2016-04-05 10:56:32 +02:00
test_static_key_base.c
test_static_keys.c locking/static_keys: Avoid nested functions 2016-02-09 10:27:29 +01:00
test_user_copy.c
test_uuid.c lib/uuid: add a test module 2016-05-30 15:26:57 -07:00
test-kstrtox.c
test-string_helpers.c lib/test-string_helpers.c: fix and improve string_get_size() tests 2016-02-03 08:28:43 -08:00
textsearch.c
timerqueue.c
ts_bm.c
ts_fsm.c
ts_kmp.c
ubsan.c UBSAN: fix typo in format string 2016-08-02 17:31:41 -04:00
ubsan.h UBSAN: run-time undefined behavior sanity checker 2016-01-20 17:09:18 -08:00
ucs2_string.c lib/ucs2_string: Correct ucs2 -> utf8 conversion 2016-02-16 12:49:05 +00:00
usercopy.c
uuid.c lib/uuid.c: use correct offset in uuid parser 2016-05-30 15:26:57 -07:00
vsprintf.c lib/uuid.c: introduce a few more generic helpers 2016-05-20 17:58:30 -07:00