Revert "VFS: make vfs_fstat() use f[get|put]_light()" #7
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This reverts commit 9b67aef.
shr-project
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Jan 24, 2022
This moves ARM over to the asm-generic/unaligned.h header. This has the
benefit of better code generated especially for ARMv7 on gcc 4.7+
compilers.
As Arnd Bergmann, points out: The asm-generic version uses the "struct"
version for native-endian unaligned access and the "byteshift" version
for the opposite endianess. The current ARM version however uses the
"byteshift" implementation for both.
Thanks to Nicolas Pitre for the excellent analysis:
Test case:
int foo (int *x) { return get_unaligned(x); }
long long bar (long long *x) { return get_unaligned(x); }
With the current ARM version:
foo:
ldrb r3, [r0, #2] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 2B], MEM[(const u8 *)x_1(D) + 2B]
ldrb r1, [r0, #1] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 1B], MEM[(const u8 *)x_1(D) + 1B]
ldrb r2, [r0, #0] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D)], MEM[(const u8 *)x_1(D)]
mov r3, r3, asl torvalds#16 @ tmp154, MEM[(const u8 *)x_1(D) + 2B],
ldrb r0, [r0, #3] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 3B], MEM[(const u8 *)x_1(D) + 3B]
orr r3, r3, r1, asl #8 @, tmp155, tmp154, MEM[(const u8 *)x_1(D) + 1B],
orr r3, r3, r2 @ tmp157, tmp155, MEM[(const u8 *)x_1(D)]
orr r0, r3, r0, asl torvalds#24 @,, tmp157, MEM[(const u8 *)x_1(D) + 3B],
bx lr @
bar:
stmfd sp!, {r4, r5, r6, r7} @,
mov r2, #0 @ tmp184,
ldrb r5, [r0, #6] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 6B], MEM[(const u8 *)x_1(D) + 6B]
ldrb r4, [r0, #5] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 5B], MEM[(const u8 *)x_1(D) + 5B]
ldrb ip, [r0, #2] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 2B], MEM[(const u8 *)x_1(D) + 2B]
ldrb r1, [r0, #4] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 4B], MEM[(const u8 *)x_1(D) + 4B]
mov r5, r5, asl torvalds#16 @ tmp175, MEM[(const u8 *)x_1(D) + 6B],
ldrb r7, [r0, #1] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 1B], MEM[(const u8 *)x_1(D) + 1B]
orr r5, r5, r4, asl #8 @, tmp176, tmp175, MEM[(const u8 *)x_1(D) + 5B],
ldrb r6, [r0, #7] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 7B], MEM[(const u8 *)x_1(D) + 7B]
orr r5, r5, r1 @ tmp178, tmp176, MEM[(const u8 *)x_1(D) + 4B]
ldrb r4, [r0, #0] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D)], MEM[(const u8 *)x_1(D)]
mov ip, ip, asl torvalds#16 @ tmp188, MEM[(const u8 *)x_1(D) + 2B],
ldrb r1, [r0, #3] @ zero_extendqisi2 @ MEM[(const u8 *)x_1(D) + 3B], MEM[(const u8 *)x_1(D) + 3B]
orr ip, ip, r7, asl #8 @, tmp189, tmp188, MEM[(const u8 *)x_1(D) + 1B],
orr r3, r5, r6, asl torvalds#24 @,, tmp178, MEM[(const u8 *)x_1(D) + 7B],
orr ip, ip, r4 @ tmp191, tmp189, MEM[(const u8 *)x_1(D)]
orr ip, ip, r1, asl torvalds#24 @, tmp194, tmp191, MEM[(const u8 *)x_1(D) + 3B],
mov r1, r3 @,
orr r0, r2, ip @ tmp171, tmp184, tmp194
ldmfd sp!, {r4, r5, r6, r7}
bx lr
In both cases the code is slightly suboptimal. One may wonder why
wasting r2 with the constant 0 in the second case for example. And all
the mov's could be folded in subsequent orr's, etc.
Now with the asm-generic version:
foo:
ldr r0, [r0, #0] @ unaligned @,* x
bx lr @
bar:
mov r3, r0 @ x, x
ldr r0, [r0, #0] @ unaligned @,* x
ldr r1, [r3, #4] @ unaligned @,
bx lr @
This is way better of course, but only because this was compiled for
ARMv7. In this case the compiler knows that the hardware can do
unaligned word access. This isn't that obvious for foo(), but if we
remove the get_unaligned() from bar as follows:
long long bar (long long *x) {return *x; }
then the resulting code is:
bar:
ldmia r0, {r0, r1} @ x,,
bx lr @
So this proves that the presumed aligned vs unaligned cases does have
influence on the instructions the compiler may use and that the above
unaligned code results are not just an accident.
Still... this isn't fully conclusive without at least looking at the
resulting assembly fron a pre ARMv6 compilation. Let's see with an
ARMv5 target:
foo:
ldrb r3, [r0, #0] @ zero_extendqisi2 @ tmp139,* x
ldrb r1, [r0, #1] @ zero_extendqisi2 @ tmp140,
ldrb r2, [r0, #2] @ zero_extendqisi2 @ tmp143,
ldrb r0, [r0, #3] @ zero_extendqisi2 @ tmp146,
orr r3, r3, r1, asl #8 @, tmp142, tmp139, tmp140,
orr r3, r3, r2, asl torvalds#16 @, tmp145, tmp142, tmp143,
orr r0, r3, r0, asl torvalds#24 @,, tmp145, tmp146,
bx lr @
bar:
stmfd sp!, {r4, r5, r6, r7} @,
ldrb r2, [r0, #0] @ zero_extendqisi2 @ tmp139,* x
ldrb r7, [r0, #1] @ zero_extendqisi2 @ tmp140,
ldrb r3, [r0, #4] @ zero_extendqisi2 @ tmp149,
ldrb r6, [r0, #5] @ zero_extendqisi2 @ tmp150,
ldrb r5, [r0, #2] @ zero_extendqisi2 @ tmp143,
ldrb r4, [r0, #6] @ zero_extendqisi2 @ tmp153,
ldrb r1, [r0, #7] @ zero_extendqisi2 @ tmp156,
ldrb ip, [r0, #3] @ zero_extendqisi2 @ tmp146,
orr r2, r2, r7, asl #8 @, tmp142, tmp139, tmp140,
orr r3, r3, r6, asl #8 @, tmp152, tmp149, tmp150,
orr r2, r2, r5, asl torvalds#16 @, tmp145, tmp142, tmp143,
orr r3, r3, r4, asl torvalds#16 @, tmp155, tmp152, tmp153,
orr r0, r2, ip, asl torvalds#24 @,, tmp145, tmp146,
orr r1, r3, r1, asl torvalds#24 @,, tmp155, tmp156,
ldmfd sp!, {r4, r5, r6, r7}
bx lr
Compared to the initial results, this is really nicely optimized and I
couldn't do much better if I were to hand code it myself.
Change-Id: I91ea5a5e83de4bbdbb53883fe0dbf00719a8e382
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tofee
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Aug 12, 2022
Syzkaller reported use-after-free bug as follows: ================================================================== BUG: KASAN: use-after-free in ntfs_ucsncmp+0x123/0x130 Read of size 2 at addr ffff8880751acee8 by task a.out/879 CPU: 7 PID: 879 Comm: a.out Not tainted 5.19.0-rc4-next-20220630-00001-gcc5218c8bd2c-dirty shr-distribution#7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x1c0/0x2b0 print_address_description.constprop.0.cold+0xd4/0x484 print_report.cold+0x55/0x232 kasan_report+0xbf/0xf0 ntfs_ucsncmp+0x123/0x130 ntfs_are_names_equal.cold+0x2b/0x41 ntfs_attr_find+0x43b/0xb90 ntfs_attr_lookup+0x16d/0x1e0 ntfs_read_locked_attr_inode+0x4aa/0x2360 ntfs_attr_iget+0x1af/0x220 ntfs_read_locked_inode+0x246c/0x5120 ntfs_iget+0x132/0x180 load_system_files+0x1cc6/0x3480 ntfs_fill_super+0xa66/0x1cf0 mount_bdev+0x38d/0x460 legacy_get_tree+0x10d/0x220 vfs_get_tree+0x93/0x300 do_new_mount+0x2da/0x6d0 path_mount+0x496/0x19d0 __x64_sys_mount+0x284/0x300 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f3f2118d9ea Code: 48 8b 0d a9 f4 0b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 76 f4 0b 00 f7 d8 64 89 01 48 RSP: 002b:00007ffc269deac8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3f2118d9ea RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffc269dec00 RBP: 00007ffc269dec80 R08: 00007ffc269deb00 R09: 00007ffc269dec44 R10: 0000000000000000 R11: 0000000000000202 R12: 000055f81ab1d220 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> The buggy address belongs to the physical page: page:0000000085430378 refcount:1 mapcount:1 mapping:0000000000000000 index:0x555c6a81d pfn:0x751ac memcg:ffff888101f7e180 anon flags: 0xfffffc00a0014(uptodate|lru|mappedtodisk|swapbacked|node=0|zone=1|lastcpupid=0x1fffff) raw: 000fffffc00a0014 ffffea0001bf2988 ffffea0001de2448 ffff88801712e201 raw: 0000000555c6a81d 0000000000000000 0000000100000000 ffff888101f7e180 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880751acd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880751ace00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8880751ace80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ^ ffff8880751acf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880751acf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== The reason is that struct ATTR_RECORD->name_offset is 6485, end address of name string is out of bounds. Fix this by adding sanity check on end address of attribute name string. [akpm@linux-foundation.org: coding-style cleanups] [chenxiaosong2@huawei.com: cleanup suggested by Hawkins Jiawei] Link: https://lkml.kernel.org/r/20220709064511.3304299-1-chenxiaosong2@huawei.com Link: https://lkml.kernel.org/r/20220707105329.4020708-1-chenxiaosong2@huawei.com Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com> Cc: Anton Altaparmakov <anton@tuxera.com> Cc: ChenXiaoSong <chenxiaosong2@huawei.com> Cc: Yongqiang Liu <liuyongqiang13@huawei.com> Cc: Zhang Yi <yi.zhang@huawei.com> Cc: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tofee
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Aug 12, 2022
…able Some cloud hypervisors do not provide IBPB on very recent CPU processors, including AMD processors affected by Retbleed. Using IBPB before firmware calls on such systems would cause a GPF at boot like the one below. Do not enable such calls when IBPB support is not present. EFI Variables Facility v0.08 2004-May-17 general protection fault, maybe for address 0x1: 0000 [shr-distribution#1] PREEMPT SMP NOPTI CPU: 0 PID: 24 Comm: kworker/u2:1 Not tainted 5.19.0-rc8+ shr-distribution#7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 Workqueue: efi_rts_wq efi_call_rts RIP: 0010:efi_call_rts Code: e8 37 33 58 ff 41 bf 48 00 00 00 49 89 c0 44 89 f9 48 83 c8 01 4c 89 c2 48 c1 ea 20 66 90 b9 49 00 00 00 b8 01 00 00 00 31 d2 <0f> 30 e8 7b 9f 5d ff e8 f6 f8 ff ff 4c 89 f1 4c 89 ea 4c 89 e6 48 RSP: 0018:ffffb373800d7e38 EFLAGS: 00010246 RAX: 0000000000000001 RBX: 0000000000000006 RCX: 0000000000000049 RDX: 0000000000000000 RSI: ffff94fbc19d8fe0 RDI: ffff94fbc1b2b300 RBP: ffffb373800d7e70 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000000b R11: 000000000000000b R12: ffffb3738001fd78 R13: ffff94fbc2fcfc00 R14: ffffb3738001fd80 R15: 0000000000000048 FS: 0000000000000000(0000) GS:ffff94fc3da00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff94fc30201000 CR3: 000000006f610000 CR4: 00000000000406f0 Call Trace: <TASK> ? __wake_up process_one_work worker_thread ? rescuer_thread kthread ? kthread_complete_and_exit ret_from_fork </TASK> Modules linked in: Fixes: 28a99e9 ("x86/amd: Use IBPB for firmware calls") Reported-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20220728122602.2500509-1-cascardo@canonical.com
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This reverts commit 9b67aef.
This is needed to get TouchPad working with latest systemd version (Yocto Warrior).