android_kernel_oneplus_msm8998/arch
Hugh Dickins fc8334e6b3 kaiser: paranoid_entry pass cr3 need to paranoid_exit
Neel Natu points out that paranoid_entry() was wrong to assume that
an entry that did not need swapgs would not need SWITCH_KERNEL_CR3:
paranoid_entry (used for debug breakpoint, int3, double fault or MCE;
though I think it's only the MCE case that is cause for concern here)
can break in at an awkward time, between cr3 switch and swapgs, but
its handling always needs kernel gs and kernel cr3.

Easy to fix in itself, but paranoid_entry() also needs to convey to
paranoid_exit() (and my reading of macro idtentry says paranoid_entry
and paranoid_exit are always paired) how to restore the prior state.
The swapgs state is already conveyed by %ebx (0 or 1), so extend that
also to convey when SWITCH_USER_CR3 will be needed (2 or 3).

(Yes, I'd much prefer that 0 meant no swapgs, whereas it's the other
way round: and a convention shared with error_entry() and error_exit(),
which I don't want to touch.  Perhaps I should have inverted the bit
for switch cr3 too, but did not.)

paranoid_exit() would be straightforward, except for TRACE_IRQS: it
did TRACE_IRQS_IRETQ when doing swapgs, but TRACE_IRQS_IRETQ_DEBUG
when not: which is it supposed to use when SWITCH_USER_CR3 is split
apart from that?  As best as I can determine, commit 5963e317b1
("ftrace/x86: Do not change stacks in DEBUG when calling lockdep")
missed the swapgs case, and should have used TRACE_IRQS_IRETQ_DEBUG
there too (the discrepancy has nothing to do with the liberal use
of _NO_STACK and _UNSAFE_STACK hereabouts: TRACE_IRQS_OFF_DEBUG has
just been used in all cases); discrepancy lovingly preserved across
several paranoid_exit() cleanups, but I'm now removing it.

Neel further indicates that to use SWITCH_USER_CR3_NO_STACK there in
paranoid_exit() is now not only unnecessary but unsafe: might corrupt
syscall entry's unsafe_stack_register_backup of %rax.  Just use
SWITCH_USER_CR3: and delete SWITCH_USER_CR3_NO_STACK altogether,
before we make the mistake of using it again.

hughd adds: this commit fixes an issue in the Kaiser-without-PCIDs
part of the series, and ought to be moved earlier, if you decided
to make a release of Kaiser-without-PCIDs.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-01-05 15:44:25 +01:00
..
alpha alpha: fix build failures 2017-12-25 14:22:16 +01:00
arc ARC: Re-enable MMU upon Machine Check exception 2017-09-27 11:00:16 +02:00
arm ARM: dma-mapping: disallow dma_get_sgtable() for non-kernel managed memory 2017-12-25 14:22:13 +01:00
arm64 arm64: Initialise high_memory global variable earlier 2017-12-25 14:22:08 +01:00
avr32 avr32: off by one in at32_init_pio() 2016-10-07 15:23:45 +02:00
blackfin pinctrl: adi2: Fix Kconfig build problem 2017-12-20 10:05:00 +01:00
c6x c6x/ptrace: Remove useless PTRACE_SETREGSET implementation 2017-03-31 09:49:53 +02:00
cris cris: Only build flash rescue image if CONFIG_ETRAX_AXISFLASHMAP is selected 2017-01-12 11:22:48 +01:00
frv mm: larger stack guard gap, between vmas 2017-06-26 07:13:11 +02:00
h8300 h8300/ptrace: Fix incorrect register transfer count 2017-03-31 09:49:53 +02:00
hexagon hexagon: fix strncpy_from_user() error return 2016-09-24 10:07:44 +02:00
ia64 ia64: copy_from_user() should zero the destination on access_ok() failure 2016-09-24 10:07:46 +02:00
m32r m32r: fix __get_user() 2016-09-24 10:07:43 +02:00
m68k m68k: Fix ndelay() macro 2016-12-15 08:49:23 -08:00
metag metag/uaccess: Check access_ok in strncpy_from_user 2017-05-25 14:30:16 +02:00
microblaze microblaze: fix copy_from_user() 2016-09-24 10:07:43 +02:00
mips MIPS: math-emu: Fix final emulation phase for certain instructions 2017-12-25 14:22:15 +01:00
mn10300 mn10300: copy_from_user() should zero on access_ok() failure... 2016-09-24 10:07:45 +02:00
nios2 nios2: reserve boot memory for device tree 2017-04-12 12:38:34 +02:00
openrisc openrisc: fix issue handling 8 byte get_user calls 2017-12-20 10:04:54 +01:00
parisc parisc: Fix validity check of pointer size argument in new CAS implementation 2017-11-30 08:37:24 +00:00
powerpc powerpc/perf: Dereference BHRB entries safely 2018-01-02 20:33:21 +01:00
s390 s390: always save and restore all registers on context switch 2017-12-16 10:33:56 +01:00
score score: fix copy_from_user() and friends 2016-09-24 10:07:44 +02:00
sh serial: sh-sci: Fix register offsets for the IRDA serial port 2017-11-15 17:13:10 +01:00
sparc sparc64/mm: set fields in deferred pages 2017-12-16 10:33:55 +01:00
tile mm: larger stack guard gap, between vmas 2017-06-26 07:13:11 +02:00
um um: Don't discard .text.exit section 2016-09-07 08:32:38 +02:00
unicore32 pwm: Changes for v4.4-rc1 2015-11-11 09:16:10 -08:00
x86 kaiser: paranoid_entry pass cr3 need to paranoid_exit 2018-01-05 15:44:25 +01:00
xtensa mm: larger stack guard gap, between vmas 2017-06-26 07:13:11 +02:00
.gitignore
Kconfig