Unlike global OOM handling, memory cgroup code will invoke the OOM killer
in any OOM situation because it has no way of telling faults occuring in
kernel context - which could be handled more gracefully - from
user-triggered faults.
Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The memcg code can trap tasks in the context of the failing allocation
until an OOM situation is resolved. They can hold all kinds of locks
(fs, mm) at this point, which makes it prone to deadlocking.
This series converts memcg OOM handling into a two step process that is
started in the charge context, but any waiting is done after the fault
stack is fully unwound.
Patches 1-4 prepare architecture handlers to support the new memcg
requirements, but in doing so they also remove old cruft and unify
out-of-memory behavior across architectures.
Patch 5 disables the memcg OOM handling for syscalls, readahead, kernel
faults, because they can gracefully unwind the stack with -ENOMEM. OOM
handling is restricted to user triggered faults that have no other
option.
Patch 6 reworks memcg's hierarchical OOM locking to make it a little
more obvious wth is going on in there: reduce locked regions, rename
locking functions, reorder and document.
Patch 7 implements the two-part OOM handling such that tasks are never
trapped with the full charge stack in an OOM situation.
This patch:
Back before smart OOM killing, when faulting tasks were killed directly on
allocation failures, the arch-specific fault handlers needed special
protection for the init process.
Now that all fault handlers call into the generic OOM killer (see commit
609838cfed: "mm: invoke oom-killer from remaining unconverted page
fault handlers"), which already provides init protection, the
arch-specific leftovers can be removed.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Acked-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc bits]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Generally minor changes. A bunch of bug fixes, particularly for
initialization and some refactoring. Most notable change if feeding the
entire flattened tree into the random pool at boot. May not be
significant, but shouldn't hurt either.
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Merge tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux
Pull device tree core updates from Grant Likely:
"Generally minor changes. A bunch of bug fixes, particularly for
initialization and some refactoring. Most notable change if feeding
the entire flattened tree into the random pool at boot. May not be
significant, but shouldn't hurt either"
Tim Bird questions whether the boot time cost of the random feeding may
be noticeable. And "add_device_randomness()" is definitely not some
speed deamon of a function.
* tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux:
of/platform: add error reporting to of_amba_device_create()
irq/of: Fix comment typo for irq_of_parse_and_map
of: Feed entire flattened device tree into the random pool
of/fdt: Clean up casting in unflattening path
of/fdt: Remove duplicate memory clearing on FDT unflattening
gpio: implement gpio-ranges binding document fix
of: call __of_parse_phandle_with_args from of_parse_phandle
of: introduce of_parse_phandle_with_fixed_args
of: move of_parse_phandle()
of: move documentation of of_parse_phandle_with_args
of: Fix missing memory initialization on FDT unflattening
of: consolidate definition of early_init_dt_alloc_memory_arch()
of: Make of_get_phy_mode() return int i.s.o. const int
include: dt-binding: input: create a DT header defining key codes.
of/platform: Staticize of_platform_device_create_pdata()
of: Specify initrd location using 64-bit
dt: Typo fix
OF: make of_property_for_each_{u32|string}() use parameters if OF is not enabled
This helps remove asid-to-mm reverse map
While mm->context.id contains the ASID assigned to a process, our ASID
allocator also used asid_mm_map[] reverse map. In a new allocation
cycle (mm->ASID >= @asid_cache), the Round Robin ASID allocator used this
to check if new @asid_cache belonged to some mm2 (from prev cycle).
If so, it could locate that mm using the ASID reverse map, and mark that
mm as unallocated ASID, to force it to refresh at the time of switch_mm()
However, for SMP, the reverse map has to be maintained per CPU, so
becomes 2 dimensional, hence got rid of it.
With reverse map gone, it is NOT possible to reach out to current
assignee. So we track the ASID allocation generation/cycle and
on every switch_mm(), check if the current generation of CPU ASID is
same as mm's ASID; If not it is refreshed.
(Based loosely on arch/sh implementation)
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ASID allocation changes/1
This patch does 2 things:
(1) get_new_mmu_context() NOW moves mm->ASID to a new value ONLY if it
was from a prev allocation cycle/generation OR if mm had no ASID
allocated (vs. before would unconditionally moving to a new ASID)
Callers desiring unconditional update of ASID, e.g.local_flush_tlb_mm()
(for parent's address space invalidation at fork) need to first force
the parent to an unallocated ASID.
(2) get_new_mmu_context() always sets the MMU PID reg with unchanged/new
ASID value.
The gains are:
- consolidation of all asid alloc logic into get_new_mmu_context()
- avoiding code duplication in switch_mm() for PID reg setting
- Enables future change to fold activate_mm() into switch_mm()
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
-Asm code already has values of SW and HW ASID values, so they can be
passed to the printing routine.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This reorganizes the current TLB operations into psuedo-ops to better
pair with MMUv4's native Insert/Delete operations
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
With previous commit freeing up PTE bits, reassign them so as to:
- Match the bit to H/w counterpart where possible
(e.g. MMUv2 GLOBAL/PRESENT, this avoids a shift in create_tlb())
- Avoid holes in _PAGE_xxx definitions
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The current ARC VM code has 13 flags in Page Table entry: some software
(accesed/dirty/non-linear-maps) and rest hardware specific. With 8k MMU
page, we need 19 bits for addressing page frame so remaining 13 bits is
just about enough to accomodate the current flags.
In MMUv4 there are 2 additional flags, SZ (normal or super page) and WT
(cache access mode write-thru) - and additionally PFN is 20 bits (vs. 19
before for 8k). Thus these can't be held in current PTE w/o making each
entry 64bit wide.
It seems there is some scope of compressing the current PTE flags (and
freeing up a few bits). Currently PTE contains fully orthogonal distinct
access permissions for kernel and user mode (Kr, Kw, Kx; Ur, Uw, Ux)
which can be folded into one set (R, W, X). The translation of 3 PTE
bits into 6 TLB bits (when programming the MMU) can be done based on
following pre-requites/assumptions:
1. For kernel-mode-only translations (vmalloc: 0x7000_0000 to
0x7FFF_FFFF), PTE additionally has PAGE_GLOBAL flag set (and user
space entries can never be global). Thus such a PTE can translate
to Kr, Kw, Kx (as appropriate) and zero for User mode counterparts.
2. For non global entries, the PTE flags can be used to create mirrored
K and U TLB bits. This is true after commit a950549c67
"ARC: copy_(to|from)_user() to honor usermode-access permissions"
which ensured that user-space translations _MUST_ have same access
permissions for both U/K mode accesses so that copy_{to,from}_user()
play fair with fault based CoW break and such...
There is no such thing as free lunch - the cost is slightly infalted
TLB-Miss Handlers.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* reduce editor lines taken by pt_regs
* ARCompact ISA specific part of TLB Miss handlers clubbed together
* cleanup some comments
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
After the recent cleanups, all the exception handlers now have same
boilerplate prologue code. Move that into common macro.
This reduces readability but helps greatly with sharing / duplicating
entry code with ARCv2 ISA where the handlers are pretty much the same,
just the entry prologue is different (due to hardware assist).
Also while at it, add the missing FAKE_RET_FROM_EXCPN calls in couple of
places to drop down to pure kernel mode (from exception mode) before
jumping off into "C" code.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
On some PAE architectures, the entire range of physical memory could reside
outside the 32-bit limit. These systems need the ability to specify the
initrd location using 64-bit numbers.
This patch globally modifies the early_init_dt_setup_initrd_arch() function to
use 64-bit numbers instead of the current unsigned long.
There has been quite a bit of debate about whether to use u64 or phys_addr_t.
It was concluded to stick to u64 to be consistent with rest of the device
tree code. As summarized by Geert, "The address to load the initrd is decided
by the bootloader/user and set at that point later in time. The dtb should not
be tied to the kernel you are booting"
More details on the discussion can be found here:
https://lkml.org/lkml/2013/6/20/690https://lkml.org/lkml/2012/9/13/544
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>
A few remaining architectures directly kill the page faulting task in an
out of memory situation. This is usually not a good idea since that
task might not even use a significant amount of memory and so may not be
the optimal victim to resolve the situation.
Since 2.6.29's 1c0fe6e ("mm: invoke oom-killer from page fault") there
is a hook that architecture page fault handlers are supposed to call to
invoke the OOM killer and let it pick the right task to kill. Convert
the remaining architectures over to this hook.
To have the previous behavior of simply taking out the faulting task the
vm.oom_kill_allocating_task sysctl can be set to 1.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc bits]
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge first patch-bomb from Andrew Morton:
- various misc bits
- I'm been patchmonkeying ocfs2 for a while, as Joel and Mark have been
distracted. There has been quite a bit of activity.
- About half the MM queue
- Some backlight bits
- Various lib/ updates
- checkpatch updates
- zillions more little rtc patches
- ptrace
- signals
- exec
- procfs
- rapidio
- nbd
- aoe
- pps
- memstick
- tools/testing/selftests updates
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (445 commits)
tools/testing/selftests: don't assume the x bit is set on scripts
selftests: add .gitignore for kcmp
selftests: fix clean target in kcmp Makefile
selftests: add .gitignore for vm
selftests: add hugetlbfstest
self-test: fix make clean
selftests: exit 1 on failure
kernel/resource.c: remove the unneeded assignment in function __find_resource
aio: fix wrong comment in aio_complete()
drivers/w1/slaves/w1_ds2408.c: add magic sequence to disable P0 test mode
drivers/memstick/host/r592.c: convert to module_pci_driver
drivers/memstick/host/jmb38x_ms: convert to module_pci_driver
pps-gpio: add device-tree binding and support
drivers/pps/clients/pps-gpio.c: convert to module_platform_driver
drivers/pps/clients/pps-gpio.c: convert to devm_* helpers
drivers/parport/share.c: use kzalloc
Documentation/accounting/getdelays.c: avoid strncpy in accounting tool
aoe: update internal version number to v83
aoe: update copyright date
aoe: perform I/O completions in parallel
...
Prepare for removing num_physpages and simplify mem_init().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com> # for arch/arc
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Concentrate code to modify totalram_pages into the mm core, so the arch
memory initialized code doesn't need to take care of it. With these
changes applied, only following functions from mm core modify global
variable totalram_pages: free_bootmem_late(), free_all_bootmem(),
free_all_bootmem_node(), adjust_managed_page_count().
With this patch applied, it will be much more easier for us to keep
totalram_pages and zone->managed_pages in consistence.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: <sworddragon2@aol.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michel Lespinasse <walken@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Address more review comments from last round of code review.
1) Enhance free_reserved_area() to support poisoning freed memory with
pattern '0'. This could be used to get rid of poison_init_mem()
on ARM64.
2) A previous patch has disabled memory poison for initmem on s390
by mistake, so restore to the original behavior.
3) Remove redundant PAGE_ALIGN() when calling free_reserved_area().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: <sworddragon2@aol.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michel Lespinasse <walken@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change signature of free_reserved_area() according to Russell King's
suggestion to fix following build warnings:
arch/arm/mm/init.c: In function 'mem_init':
arch/arm/mm/init.c:603:2: warning: passing argument 1 of 'free_reserved_area' makes integer from pointer without a cast [enabled by default]
free_reserved_area(__va(PHYS_PFN_OFFSET), swapper_pg_dir, 0, NULL);
^
In file included from include/linux/mman.h:4:0,
from arch/arm/mm/init.c:15:
include/linux/mm.h:1301:22: note: expected 'long unsigned int' but argument is of type 'void *'
extern unsigned long free_reserved_area(unsigned long start, unsigned long end,
mm/page_alloc.c: In function 'free_reserved_area':
>> mm/page_alloc.c:5134:3: warning: passing argument 1 of 'virt_to_phys' makes pointer from integer without a cast [enabled by default]
In file included from arch/mips/include/asm/page.h:49:0,
from include/linux/mmzone.h:20,
from include/linux/gfp.h:4,
from include/linux/mm.h:8,
from mm/page_alloc.c:18:
arch/mips/include/asm/io.h:119:29: note: expected 'const volatile void *' but argument is of type 'long unsigned int'
mm/page_alloc.c: In function 'free_area_init_nodes':
mm/page_alloc.c:5030:34: warning: array subscript is below array bounds [-Warray-bounds]
Also address some minor code review comments.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: <sworddragon2@aol.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michel Lespinasse <walken@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings. In any case, they are temporary and harmless.
This removes all the arch/arc uses of the __cpuinit macros from
all C files. Currently arc does not have any __CPUINIT used in
assembly files.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
LOAD_FAULT_PTE macro is expected to set r2 with faulting vaddr.
However in case of CONFIG_ARC_DBG_TLB_MISS_COUNT, it was getting
clobbered with statistics collection code.
Fix latter by using a different register.
Note that only I-TLB Miss handler was potentially affected.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* No need to check for READ access in I-TLB Miss handler
* Redundant PAGE_PRESENT update in PTE
Post TLB entry installation, in updating PTE for software accessed/dity
bits, no need to update PAGE_PRESENT since it will already be set.
Infact the entry won't have installed if !PAGE_PRESENT.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
With ECR now part of pt_regs
* No need to propagate from lowest asm handlers as arg
* No need to save it in tsk->thread.cause_code
* Avoid bit chopping to access the bit-fields
More code consolidation, cleanup
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This can be ascertained within do_page_fault() since it gets the full
ECR (Exception Cause Register).
Further, for both the callers of do_page_fault(): Prot-V / D-TLB-Miss,
the cause sub-fields in ECR are same for same type of access, making the
code much more simpler.
D-TLB-Miss [LD] 0x00_21_01_00
Prot-V [LD] 0x00_23_01_00
^^
D-TLB-Miss [ST] 0x00_21_02_00
Prot-V [ST] 0x00_23_02_00
^^
D-TLB-Miss [EX] 0x00_21_03_00
Prot-V [EX] 0x00_23_03_00
^^
This helps code consolidation, which is even better when moving code from
assembler to "C".
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Non-congruent SRC page in copy_user_page() is dcache clean in the end -
so record that fact, to avoid a subsequent extraneous flush.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* Number of (i|d)cache ways can be retrieved from BCRs and hence no need
to cross check with with built-in constants
* Use of IS_ENABLED() to check for a Kconfig option
* is_not_cache_aligned() not used anymore
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* Move the various sub-system defines/types into relevant files/functions
(reduces compilation time)
* move CPU specific stuff out of asm/tlb.h into asm/mmu.h
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
gdbserver inserting a breakpoint ends up calling copy_user_page() for a
code page. The generic version of which (non-aliasing config) didn't set
the PG_arch_1 bit hence update_mmu_cache() didn't sync dcache/icache for
corresponding dynamic loader code page - causing garbade to be executed.
So now aliasing versions of copy_user_highpage()/clear_page() are made
default. There is no significant overhead since all of special alias
handling code is compiled out for non-aliasing build
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The VM_EXEC check in update_mmu_cache() was getting optimized away
because of a stupid error in definition of macro addr_not_cache_congruent()
The intention was to have the equivalent of following:
if (a || (1 ? b : 0))
but we ended up with following:
if (a || 1 ? b : 0)
And because precedence of '||' is more that that of '?', gcc was optimizing
away evaluation of <a>
Nasty Repercussions:
1. For non-aliasing configs it would mean some extraneous dcache flushes
for non-code pages if U/K mappings were not congruent.
2. For aliasing config, some needed dcache flush for code pages might
be missed if U/K mappings were congruent.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This manifested as grep failing psuedo-randomly:
-------------->8---------------------
[ARCLinux]$ ip address show lo | grep inet
[ARCLinux]$ ip address show lo | grep inet
[ARCLinux]$ ip address show lo | grep inet
[ARCLinux]$
[ARCLinux]$ ip address show lo | grep inet
inet 127.0.0.1/8 scope host lo
-------------->8---------------------
ARC700 MMU provides fully orthogonal permission bits per page:
Ur, Uw, Ux, Kr, Kw, Kx
The user mode page permission templates used to have all Kernel mode
access bits enabled.
This caused a tricky race condition observed with uClibc buffered file
read and UNIX pipes.
1. Read access to an anon mapped page in libc .bss: write-protected
zero_page mapped: TLB Entry installed with Ur + K[rwx]
2. grep calls libc:getc() -> buffered read layer calls read(2) with the
internal read buffer in same .bss page.
The read() call is on STDIN which has been redirected to a pipe.
read(2) => sys_read() => pipe_read() => copy_to_user()
3. Since page has Kernel-write permission (despite being user-mode
write-protected), copy_to_user() suceeds w/o taking a MMU TLB-Miss
Exception (page-fault for ARC). core-MM is unaware that kernel
erroneously wrote to the reserved read-only zero-page (BUG #1)
4. Control returns to userspace which now does a write to same .bss page
Since Linux MM is not aware that page has been modified by kernel, it
simply reassigns a new writable zero-init page to mapping, loosing the
prior write by kernel - effectively zero'ing out the libc read buffer
under the hood - hence grep doesn't see right data (BUG #2)
The fix is to make all kernel-mode access permissions mirror the
user-mode ones. Note that the kernel still has full access to pages,
when accessed directly (w/o MMU) - this fix ensures that kernel-mode
access in copy_to_from() path uses the same faulting access model as for
pure user accesses to keep MM fully aware of page state.
The issue is peudo-random because it only shows up if the TLB entry
installed in #1 is present at the time of #3. If it is evicted out, due
to TLB pressure or some-such, then copy_to_user() does take a TLB Miss
Exception, with a routine write-to-anon COW processing installing a
fresh page for kernel writes and also usable as it is in userspace.
Further the issue was dormant for so long as it depends on where the
libc internal read buffer (in .bss) is mapped at runtime.
If it happens to reside in file-backed data mapping of libc (in the
page-aligned slack space trailing the file backed data), loader zero
padding the slack space, does the early cow page replacement, setting
things up at the very beginning itself.
With gcc 4.8 based builds, the libc buffer got pushed out to a real
anon mapping which triggers the issue.
Reported-by: Anton Kolesov <akolesov@synopsys.com>
Cc: <stable@vger.kernel.org> # 3.9
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Flush and INVALIDATE the dcache page.
This helper is only used for writeback of CODE pages to memory. So
there's no value in keeping the dcache lines around. Infact it is risky
as a writeback on natural eviction under pressure can cause un-needed
writeback with weird issues on aliasing dcache configurations.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
I'm satisified with testing, specially with fuse which has historically given
grief to VIPT arches (ARM/PARISC...)
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Merge tag 'arc-v3.10-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc
Pull second set of arc arch updates from Vineet Gupta:
"Aliasing VIPT dcache support for ARC
I'm satisified with testing, specially with fuse which has
historically given grief to VIPT arches (ARM/PARISC...)"
* tag 'arc-v3.10-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
ARC: [TB10x] Remove GENERIC_GPIO
ARC: [mm] Aliasing VIPT dcache support 4/4
ARC: [mm] Aliasing VIPT dcache support 3/4
ARC: [mm] Aliasing VIPT dcache support 2/4
ARC: [mm] Aliasing VIPT dcache support 1/4
ARC: [mm] refactor the core (i|d)cache line ops loops
ARC: [mm] serious bug in vaddr based icache flush
* Support for two new platforms based on ARC700
- Abilis TB10x SoC [Chritisian/Pierrick]
- Simulator only System-C Model [Mischa]
* ARC specific MM improvements
- Avoid full TLB flush (ASID increment) on munmap (even single page)
- VIPT Cache Flushing improvements
+ Delayed dcache flush for non-aliasing dcache (big performance boost)
+ icache flush aliasing agnostic (no need to kill all possible aliases)
* Others
- Avoid needless rebuild of DTB files for every kernel build
- Remove builtin cmdline as that is already provided by DeviceTree/bootargs
- Fixing unaligned access emulation corner case
- checkpatch fixes [Sachin]
- Various fixlets [Noam]
- Minor build failures/cleanups
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Merge tag 'arc-v3.10-rc1-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc
Pull ARC port updates from Vineet Gupta:
"Support for two new platforms based on ARC700:
- Abilis TB10x SoC [Chritisian/Pierrick]
- Simulator only System-C Model [Mischa]
ARC specific MM improvements:
- Avoid full TLB flush (ASID increment) on munmap (even single page)
- VIPT Cache Flushing improvements
+ Delayed dcache flush for non-aliasing dcache (big performance boost)
+ icache flush aliasing agnostic (no need to kill all possible aliases)
Others:
- Avoid needless rebuild of DTB files for every kernel build
- Remove builtin cmdline as that is already provided by DeviceTree/bootargs
- Fixing unaligned access emulation corner case
- checkpatch fixes [Sachin]
- Various fixlets [Noam]
- Minor build failures/cleanups"
* tag 'arc-v3.10-rc1-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (35 commits)
ARC: [mm] Lazy D-cache flush (non aliasing VIPT)
ARC: [mm] micro-optimize page size icache invalidate
ARC: [mm] remove the pessimistic all-alias-invalidate icache helpers
ARC: [mm] consolidate icache/dcache sync code
ARC: [mm] optimise icache flush for kernel mappings
ARC: [mm] optimise icache flush for user mappings
ARC: [mm] optimize needless full mm TLB flush on munmap
ARC: Add support for nSIM OSCI System C model
ARC: [TB10x] Adapt device tree to new compatible string
ARC: [TB10x] Add support for TB10x platform
ARC: [TB10x] Device tree of TB100 and TB101 Development Kits
ARC: Prepare interrupt code for external controllers
ARC: Allow embedded arc-intc to be properly placed in DT intc hierarchy
ARC: [cmdline] Don't overwrite u-boot provided bootargs
ARC: [cmdline] Remove CONFIG_CMDLINE
ARC: [plat-arcfpga] defconfig update
ARC: unaligned access emulation broken if callee-reg dest of LD/ST
ARC: unaligned access emulation error handling consolidation
ARC: Debug/crash-printing Improvements
ARC: fix typo with clock speed
...
This is the meat of the series which prevents any dcache alias creation
by always keeping the U and K mapping of a page congruent.
If a mapping already exists, and other tries to access the page, prev
one is flushed to physical page (wback+inv)
Essentially flush_dcache_page()/copy_user_highpage() create K-mapping
of a page, but try to defer flushing, unless U-mapping exist.
When page is actually mapped to userspace, update_mmu_cache() flushes
the K-mapping (in certain cases this can be optimised out)
Additonally flush_cache_mm(), flush_cache_range(), flush_cache_page()
handle the puring of stale userspace mappings on exit/munmap...
flush_anon_page() handles the existing U-mapping for anon page before
kernel reads it via the GUP path.
Note that while not complete, this is enough to boot a simple
dynamically linked Busybox based rootfs
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This preps the low level dcache flush helpers to take vaddr argument in
addition to the existing paddr to properly flush the VIPT dcache
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Nothing semantical
* simplify the alignement code by using & operation only
* rename variables clearly as paddr
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
vaddr used to index the cache was clipped from the wrong end, and thus
would potentially fail to flush the correct lines.
The problem was dorment for so long because up until the recent
optimizations it was only used for ptrace break-point only flushes.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
flush_dcache_page( ) is MM hook to ensure that a page has consistent
views between kernel and userspace. Thus it is called when
* kernel writes to a page which at some later point could get mapped to
userspace (so kernel mapping needs to be flushed-n-inv)
* kernel is about to read from a page with possible userspace mappings
(so userspace mappings needs to be made coherent with kernel ones)
However for Non aliasing VIPT dcache, any userspace mapping will always
be congruent to kernel mapping. Thus d-cache need need not be flushed at
all (or delayed indefinitely).
The only reason it does need to be flushed is when mapping code pages.
Since icache doesn't snoop dcache, those dirty dcache lines need to be
written back to memory and icache line invalidated so that icache lines
fetch will get the right data.
Decent gains on LMBench fork/exec/sh and File I/O micro-benchmarks.
(1) FPGA @ 80 MHZ
Processor, Processes - times in microseconds - smaller is better
------------------------------------------------------------------------------
Host OS Mhz null null open slct sig sig fork exec sh
call I/O stat clos TCP inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
3.9-rc6-a Linux 3.9.0-r 80 4.79 8.72 66.7 116. 239. 8.39 30.4 4798 14.K 34.K
3.9-rc6-b Linux 3.9.0-r 80 4.79 8.62 65.4 111. 239. 8.35 29.0 3995 12.K 30.K
3.9-rc7-c Linux 3.9.0-r 80 4.79 9.00 66.1 106. 239. 8.61 30.4 2858 10.K 24.K
^^^^ ^^^^ ^^^
File & VM system latencies in microseconds - smaller is better
-------------------------------------------------------------------------------
Host OS 0K File 10K File Mmap Prot Page 100fd
Create Delete Create Delete Latency Fault Fault selct
--------- ------------- ------ ------ ------ ------ ------- ----- ------- -----
3.9-rc6-a Linux 3.9.0-r 317.8 204.2 1122.3 375.1 3522.0 4.288 20.7 126.8
3.9-rc6-b Linux 3.9.0-r 298.7 223.0 1141.6 367.8 3531.0 4.866 20.9 126.4
3.9-rc7-c Linux 3.9.0-r 278.4 179.2 862.1 339.3 3705.0 3.223 20.3 126.6
^^^^^ ^^^^^ ^^^^^ ^^^^
(2) Customer Silicon @ 500 MHz (166 MHz mem)
------------------------------------------------------------------------------
Host OS Mhz null null open slct sig sig fork exec sh
call I/O stat clos TCP inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
abilis-ba Linux 3.9.0-r 497 0.71 1.38 4.58 12.0 35.5 1.40 3.89 2070 5525 13.K
abilis-ca Linux 3.9.0-r 497 0.71 1.40 4.61 11.8 35.6 1.37 3.92 1411 4317 10.K
^^^^ ^^^^ ^^^
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
start address is already page aligned and size is const PAGE_SIZE,
thus fixups for alignment not needed in generated code.
bloat-o-meter vmlinux-mm5 vmlinux
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-32 (-32)
function old new delta
__inv_icache_page 82 50 -32
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Now that we have same helper used for all icache invalidates (i.e.
vaddr+paddr based exact line invalidate), consolidate the open coded
calls into one place.
Also rename flush_icache_range_vaddr => __sync_icache_dcache
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This change continues the theme from prev commit - this time icache
handling for kernel's own code modification (vmalloc: loadable modules,
breakpoints for kprobes/kgdb...)
flush_icache_range() calls the CDU icache helper with vaddr to enable
exact line invalidate.
For a true kernel-virtual mapping, the vaddr is actually virtual hence
valid as index into cache. For kprobes breakpoint however, the vaddr arg
is actually paddr - since that's how normal kernel is mapped in ARC
memory map. This implies that CDU will use the same addr for
indexing as for tag match - which is fine since kernel code would only
have that "implicit" mapping and none other.
This should speed up module loading significantly - specially on default
ARC700 icache configurations (32k) which alias.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC icache doesn't snoop dcache thus executable pages need to be made
coherent before mapping into userspace in flush_icache_page().
However ARC700 CDU (hardware cache flush module) requires both vaddr
(index in cache) as well as paddr (tag match) to correctly identify a
line in the VIPT cache. A typical ARC700 SoC has aliasing icache, thus
the paddr only based flush_icache_page() API couldn't be implemented
efficiently. It had to loop thru all possible alias indexes and perform
the invalidate operation (ofcourse the cache op would only succeed at
the index(es) where tag matches - typically only 1, but the cost of
visiting all the cache-bins needs to paid nevertheless).
Turns out however that the vaddr (along with paddr) is available in
update_mmu_cache() hence better suits ARC icache flush semantics.
With both vaddr+paddr, exactly one flush operation per line is done.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
