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Vineet Gupta cbfe74a753 ARCv2: STAR 9000950267: Handle return from intr to Delay Slot #2 
Returning to delay slot, riding an interrupti, had one loose end.
AUX_USER_SP used for restoring user mode SP upon RTIE was not being
setup from orig task's saved value, causing task to use wrong SP,
leading to ProtV errors.

The reason being:
 - INTERRUPT_EPILOGUE returns to a kernel trampoline, thus not expected to restore it
 - EXCEPTION_EPILOGUE is not used at all

Fix that by restoring AUX_USER_SP explicitly in the trampoline.

This was broken in the original workaround, but the error scenarios got
reduced considerably since v3.14 due to following:

 1. The Linuxthreads.old based userspace at the time caused many more
    exceptions in delay slot than the current NPTL based one.
    Infact with current userspace the error doesn't happen at all.

 2. Return from interrupt (delay slot or otherwise) doesn't get exercised much
    after commit 4de0e52867 ("Really Re-enable interrupts to avoid deadlocks")
    since IRQ_ACTIVE.active being clear means most returns are as if from pure
    kernel (even for active interrupts)

Infact the issue only happened in an experimental branch where I was tinkering with
reverted 4de0e52867

Cc: stable@kernel.org # v4.2+
Fixes: 4255b07f2c ("ARCv2: STAR 9000793984: Handle return from intr to Delay Slot")
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2016-01-22 17:25:03 +05:30
..
alpha mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage 2015-11-05 19:34:48 -08:00
arc ARCv2: STAR 9000950267: Handle return from intr to Delay Slot #2 2016-01-22 17:25:03 +05:30
arm ARM: SoC fixes for 4.4-rc 2016-01-08 16:11:05 -08:00
arm64 Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-12-13 12:41:10 -08:00
avr32 dmaengine updates for 4.4-rc1 2015-11-10 10:05:17 -08:00
blackfin treewide: Remove old email address 2015-11-23 09:44:58 +01:00
c6x
cris cris: Drop reference to get_cmos_time() 2015-11-02 20:03:05 +01:00
frv kmap_atomic_to_page() has no users, remove it 2015-11-09 15:11:24 -08:00
h8300 h8300 update for v4.4 2015-11-12 15:26:39 -08:00
hexagon
ia64 [IA64] Enable mlock2 syscall for ia64 2015-12-14 10:30:02 -08:00
m32r m32r: add io*_rep helpers 2015-12-29 17:45:49 -08:00
m68k m68k: Wire up mlock2 2015-11-22 11:35:26 +01:00
metag Metag architecture changes for v4.4 2015-11-10 16:24:25 -08:00
microblaze Revert "scatterlist: use sg_phys()" 2015-12-15 12:54:06 -08:00
mips Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-01-06 16:15:03 -08:00
mn10300 mn10300: Select CONFIG_HAVE_UID16 to fix build failure 2015-11-30 07:01:40 -08:00
nios2 nios2: fix cache coherency 2015-11-26 22:25:58 +08:00
openrisc
parisc parisc: Fix syscall restarts 2015-12-21 10:16:18 +01:00
powerpc net: filter: make JITs zero A for SKF_AD_ALU_XOR_X 2016-01-06 00:43:52 -05:00
s390 s390/dis: Fix handling of format specifiers 2015-12-18 14:43:21 +01:00
score
sh sh64: fix __NR_fgetxattr 2015-12-12 10:15:34 -08:00
sparc net: filter: make JITs zero A for SKF_AD_ALU_XOR_X 2016-01-06 00:43:52 -05:00
tile tile: provide CONFIG_PAGE_SIZE_64KB etc for tilepro 2016-01-05 08:16:09 -05:00
um um: fix returns without va_end 2015-12-08 22:26:00 +01:00
unicore32 pwm: Changes for v4.4-rc1 2015-11-11 09:16:10 -08:00
x86 A simple fix. I'm sending it before the merge window, because it refines 2016-01-08 15:58:14 -08:00
xtensa Merge branch 'for-4.4/io-poll' of git://git.kernel.dk/linux-block 2015-11-10 17:23:49 -08:00
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