648d4e3957
[ Upstream commit 23c0cbd0c75c3b564850294427fd2be2bc2a015b ]
Upon a taken interrupt/exception from User mode, HS hardware auto sets Z flag.
This helps shave a few instructions from EXCEPTION_PROLOGUE by eliding
re-reading ERSTATUS and some bit fiddling.
However TLB Miss Exception handler can clobber the CPU flags and still end
up in EXCEPTION_PROLOGUE in the slow path handling TLB handling case:
EV_TLBMissD
do_slow_path_pf
EV_TLBProtV (aliased to call_do_page_fault)
EXCEPTION_PROLOGUE
As a result, EXCEPTION_PROLOGUE need to "unclobber" the Z flag which this
patch changes. It is now pushed out to TLB Miss Exception handler.
The reasons beings:
- The flag restoration is only needed for slowpath TLB Miss Exception
handling, but currently being in EXCEPTION_PROLOGUE penalizes all
exceptions such as ProtV and syscall Trap, where Z flag is already
as expected.
- Pushing unclobber out to where it was clobbered is much cleaner and
also serves to document the fact.
- Makes EXCEPTION_PROLGUE similar to INTERRUPT_PROLOGUE so easier to
refactor the common parts which is what this series aims to do
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Stable-dep-of: 92e2921eeafd ("ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef __ASSEMBLY__ guard")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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| .. | ||
| cache.c | ||
| dma.c | ||
| extable.c | ||
| fault.c | ||
| highmem.c | ||
| init.c | ||
| ioremap.c | ||
| Makefile | ||
| mmap.c | ||
| tlb.c | ||
| tlbex.S | ||