Both pgtable_cache_init() and pgd_cache_init() are used to initialize kmem
cache for page table allocations on several architectures that do not use
PAGE_SIZE tables for one or more levels of the page table hierarchy.
Most architectures do not implement these functions and use __weak default
NOP implementation of pgd_cache_init(). Since there is no such default
for pgtable_cache_init(), its empty stub is duplicated among most
architectures.
Rename the definitions of pgd_cache_init() to pgtable_cache_init() and
drop empty stubs of pgtable_cache_init().
Link: http://lkml.kernel.org/r/1566457046-22637-1-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Will Deacon <will@kernel.org> [arm64]
Acked-by: Thomas Gleixner <tglx@linutronix.de> [x86]
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The mips code is mostly equivalent to the generic one, minus various
bugfixes and an arch override for gup_fast_permitted.
Note that this defines ARCH_HAS_PTE_SPECIAL for mips as mips has
pte_special and pte_mkspecial implemented and used in the existing gup
code. They are no-op stubs, though which makes me a little unsure if this
is really right thing to do.
Note that this also adds back a missing cpu_has_dc_aliases check for
__get_user_pages_fast, which the old code was only doing for
get_user_pages_fast. This clearly looks like an oversight, as any
condition that makes get_user_pages_fast unsafe also applies to
__get_user_pages_fast.
[hch@lst.de: MIPS: don't select ARCH_HAS_PTE_SPECIAL]
Link: http://lkml.kernel.org/r/20190701151818.32227-3-hch@lst.de
Link: http://lkml.kernel.org/r/20190625143715.1689-5-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 46011e6ea3 ("MIPS: Make set_pte() SMP safe.") introduced an
open-coded version of cmpxchg() within set_pte(), that always operated
on a value the size of an unsigned long. That is, it used ll/sc
instructions when CONFIG_32BIT=y or lld/scd instructions when
CONFIG_64BIT=y.
This was broken for configurations in which pte_t is larger than an
unsigned long (with the exception of XPA configurations which have a
different implementation of set_pte()), because we no longer update the
whole PTE. Indeed commit 46011e6ea3 ("MIPS: Make set_pte() SMP safe.")
notes:
> The case of CONFIG_64BIT_PHYS_ADDR && CONFIG_CPU_MIPS32 is *not*
> handled.
In practice this affects Netlogic XLR/XLS systems including
nlm_xlr_defconfig.
Commit 82f4f66ddf ("MIPS: Remove open-coded cmpxchg() in set_pte()")
then replaced this open-coded version of cmpxchg() with an actual call
to cmpxchg(). Unfortunately the configurations mentioned above then fail
to build because cmpxchg() can only operate on values 32 bits or smaller
in size, resulting in:
arch/mips/include/asm/cmpxchg.h:166:11: error:
call to '__cmpxchg_called_with_bad_pointer' declared with
attribute error: Bad argument size for cmpxchg
One option that would fix the build failure & restore the previous
behaviour would be to cast the pte pointer to a pointer to unsigned
long, so that cmpxchg() would operate on just 32 bits of the PTE as it
has been since commit 46011e6ea3 ("MIPS: Make set_pte() SMP safe.").
That feels like an ugly hack though, and the behaviour of set_pte() is
likely a little broken.
Instead we take advantage of the fact that the affected configurations
already know at compile time that the CPU will support 64 bits (ie. have
hardcoded cpu_has_64bits in cpu-feature-overrides.h) in order to allow
cmpxchg64() to be used in these configurations. set_pte() then makes use
of cmpxchg64() when necessary.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: 46011e6ea3 ("MIPS: Make set_pte() SMP safe.")
Fixes: 82f4f66ddf ("MIPS: Remove open-coded cmpxchg() in set_pte()")
set_pte() contains an open coded version of cmpxchg() - it atomically
replaces the buddy pte's value if it is currently zero. Simplify the
code considerably by just using cmpxchg() instead of reinventing it.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
We currently have 2 commonly used methods for switching ISA within
assembly code, then restoring the original ISA.
1) Using a pair of .set push & .set pop directives. For example:
.set push
.set mips32r2
<some_insn>
.set pop
2) Using .set mips0 to restore the ISA originally specified on the
command line. For example:
.set mips32r2
<some_insn>
.set mips0
Unfortunately method 2 does not work with nanoMIPS toolchains, where the
assembler rejects the .set mips0 directive like so:
Error: cannot change ISA from nanoMIPS to mips0
In preparation for supporting nanoMIPS builds, switch all instances of
method 2 in generic non-platform-specific code to use push & pop as in
method 1 instead. The .set push & .set pop is arguably cleaner anyway,
and if nothing else it's good to consistently use one method.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21037/
Cc: linux-mips@linux-mips.org
In response to compile breakage introduced by a series that added the
pud_write helper to x86, Stephen notes:
did you consider using the other paradigm:
In arch include files:
#define pud_write pud_write
static inline int pud_write(pud_t pud)
.....
Then in include/asm-generic/pgtable.h:
#ifndef pud_write
tatic inline int pud_write(pud_t pud)
{
....
}
#endif
If you had, then the powerpc code would have worked ... ;-) and many
of the other interfaces in include/asm-generic/pgtable.h are
protected that way ...
Given that some architecture already define pmd_write() as a macro, it's
a net reduction to drop the definition of __HAVE_ARCH_PMD_WRITE.
Link: http://lkml.kernel.org/r/151129126721.37405.13339850900081557813.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Suggested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Oliver OHalloran <oliveroh@au1.ibm.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We get 1 warning when building kernel with W=1:
drivers/char/mem.c:220:12: warning: no previous prototype for 'phys_mem_access_prot_allowed' [-Wmissing-prototypes]
int __weak phys_mem_access_prot_allowed(struct file *file,
In fact, its declaration is spreading to several header files in
different architecture, but need to be declare in common header file.
So this patch moves phys_mem_access_prot_allowed() to pgtable.h.
Link: http://lkml.kernel.org/r/1473751597-12139-1-git-send-email-baoyou.xie@linaro.org
Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The use of config_enabled() against config options is ambiguous. In
practical terms, config_enabled() is equivalent to IS_BUILTIN(), but the
author might have used it for the meaning of IS_ENABLED(). Using
IS_ENABLED(), IS_BUILTIN(), IS_MODULE() etc. makes the intention
clearer.
This commit replaces config_enabled() with IS_ENABLED() where possible.
This commit is only touching bool config options.
I noticed two cases where config_enabled() is used against a tristate
option:
- config_enabled(CONFIG_HWMON)
[ drivers/net/wireless/ath/ath10k/thermal.c ]
- config_enabled(CONFIG_BACKLIGHT_CLASS_DEVICE)
[ drivers/gpu/drm/gma500/opregion.c ]
I did not touch them because they should be converted to IS_BUILTIN()
in order to keep the logic, but I was not sure it was the authors'
intention.
Link: http://lkml.kernel.org/r/1465215656-20569-1-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Stas Sergeev <stsp@list.ru>
Cc: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Joshua Kinard <kumba@gentoo.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: yu-cheng yu <yu-cheng.yu@intel.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Will Drewry <wad@chromium.org>
Cc: Nikolay Martynov <mar.kolya@gmail.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Rafal Milecki <zajec5@gmail.com>
Cc: James Cowgill <James.Cowgill@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Mikko Rapeli <mikko.rapeli@iki.fi>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Tony Wu <tung7970@gmail.com>
Cc: Huaitong Han <huaitong.han@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Gelmini <andrea.gelmini@gelma.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Rabin Vincent <rabin@rab.in>
Cc: "Maciej W. Rozycki" <macro@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The following testcase may result in a page table entries with a invalid
CCA field being generated:
static void *bindstack;
static int sysrqfd;
static void protect_low(int protect)
{
mprotect(bindstack, BINDSTACK_SIZE, protect);
}
static void sigbus_handler(int signal, siginfo_t * info, void *context)
{
void *addr = info->si_addr;
write(sysrqfd, "x", 1);
printf("sigbus, fault address %p (should not happen, but might)\n",
addr);
abort();
}
static void run_bind_test(void)
{
unsigned int *p = bindstack;
p[0] = 0xf001f001;
write(sysrqfd, "x", 1);
/* Set trap on access to p[0] */
protect_low(PROT_NONE);
write(sysrqfd, "x", 1);
/* Clear trap on access to p[0] */
protect_low(PROT_READ | PROT_WRITE | PROT_EXEC);
write(sysrqfd, "x", 1);
/* Check the contents of p[0] */
if (p[0] != 0xf001f001) {
write(sysrqfd, "x", 1);
/* Reached, but shouldn't be */
printf("badness, shouldn't happen but does\n");
abort();
}
}
int main(void)
{
struct sigaction sa;
sysrqfd = open("/proc/sysrq-trigger", O_WRONLY);
if (sigprocmask(SIG_BLOCK, NULL, &sa.sa_mask)) {
perror("sigprocmask");
return 0;
}
sa.sa_sigaction = sigbus_handler;
sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
if (sigaction(SIGBUS, &sa, NULL)) {
perror("sigaction");
return 0;
}
bindstack = mmap(NULL,
BINDSTACK_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (bindstack == MAP_FAILED) {
perror("mmap bindstack");
return 0;
}
printf("bindstack: %p\n", bindstack);
run_bind_test();
printf("done\n");
return 0;
}
There are multiple ingredients for this:
1) PAGE_NONE is defined to _CACHE_CACHABLE_NONCOHERENT, which is CCA 3
on all platforms except SB1 where it's CCA 5.
2) _page_cachable_default must have bits set which are not set
_CACHE_CACHABLE_NONCOHERENT.
3) Either the defective version of pte_modify for XPA or the standard
version must be in used. However pte_modify for the 36 bit address
space support is no affected.
In that case additional bits in the final CCA mode may generate an invalid
value for the CCA field. On the R10000 system where this was tracked
down for example a CCA 7 has been observed, which is Uncached Accelerated.
Fixed by:
1) Using the proper CCA mode for PAGE_NONE just like for all the other
PAGE_* pte/pmd bits.
2) Fix the two affected variants of pte_modify.
Further code inspection also shows the same issue to exist in pmd_modify
which would affect huge page systems.
Issue in pte_modify tracked down by Alastair Bridgewater, PAGE_NONE
and pmd_modify issue found by me.
The history of this goes back beyond Linus' git history. Chris Dearman's
commit 351336929c ("[MIPS] Allow setting of
the cache attribute at run time.") missed the opportunity to fix this
but it was originally introduced in lmo commit
d523832cf12007b3242e50bb77d0c9e63e0b6518 ("Missing from last commit.")
and 32cc38229ac7538f2346918a09e75413e8861f87 ("New configuration option
CONFIG_MIPS_UNCACHED.")
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reported-by: Alastair Bridgewater <alastair.bridgewater@gmail.com>
Merge updates from Andrew Morton:
- fsnotify fix
- poll() timeout fix
- a few scripts/ tweaks
- debugobjects updates
- the (small) ocfs2 queue
- Minor fixes to kernel/padata.c
- Maybe half of the MM queue
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (117 commits)
mm, page_alloc: restore the original nodemask if the fast path allocation failed
mm, page_alloc: uninline the bad page part of check_new_page()
mm, page_alloc: don't duplicate code in free_pcp_prepare
mm, page_alloc: defer debugging checks of pages allocated from the PCP
mm, page_alloc: defer debugging checks of freed pages until a PCP drain
cpuset: use static key better and convert to new API
mm, page_alloc: inline pageblock lookup in page free fast paths
mm, page_alloc: remove unnecessary variable from free_pcppages_bulk
mm, page_alloc: pull out side effects from free_pages_check
mm, page_alloc: un-inline the bad part of free_pages_check
mm, page_alloc: check multiple page fields with a single branch
mm, page_alloc: remove field from alloc_context
mm, page_alloc: avoid looking up the first zone in a zonelist twice
mm, page_alloc: shortcut watermark checks for order-0 pages
mm, page_alloc: reduce cost of fair zone allocation policy retry
mm, page_alloc: shorten the page allocator fast path
mm, page_alloc: check once if a zone has isolated pageblocks
mm, page_alloc: move __GFP_HARDWALL modifications out of the fastpath
mm, page_alloc: simplify last cpupid reset
mm, page_alloc: remove unnecessary initialisation from __alloc_pages_nodemask()
...
I've just discovered that the useful-sounding has_transparent_hugepage()
is actually an architecture-dependent minefield: on some arches it only
builds if CONFIG_TRANSPARENT_HUGEPAGE=y, on others it's also there when
not, but on some of those (arm and arm64) it then gives the wrong
answer; and on mips alone it's marked __init, which would crash if
called later (but so far it has not been called later).
Straighten this out: make it available to all configs, with a sensible
default in asm-generic/pgtable.h, removing its definitions from those
arches (arc, arm, arm64, sparc, tile) which are served by the default,
adding #define has_transparent_hugepage has_transparent_hugepage to
those (mips, powerpc, s390, x86) which need to override the default at
runtime, and removing the __init from mips (but maybe that kind of code
should be avoided after init: set a static variable the first time it's
called).
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc]
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [arch/s390]
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are 2 distinct cases in which a kernel for a MIPS32 CPU
(CONFIG_CPU_MIPS32=y) may use 64 bit physical addresses
(CONFIG_PHYS_ADDR_T_64BIT=y):
- 36 bit physical addressing as used by RMI Alchemy & Netlogic XLP/XLR
CPUs.
- MIPS32r5 eXtended Physical Addressing (XPA).
These 2 cases are distinct in that they require different behaviour from
the kernel - the EntryLo registers have different formats. Until Linux
v4.1 we only supported the first case, with code conditional upon the 2
aforementioned Kconfig variables being set. Commit c5b367835c ("MIPS:
Add support for XPA.") added support for the second case, but did so by
modifying the code that existed for the first case rather than treating
the 2 cases as distinct. Since the EntryLo registers have different
formats this breaks the 36 bit Alchemy/XLP/XLR case. Fix this by
splitting the 2 cases, with XPA cases now being conditional upon
CONFIG_XPA and the non-XPA case matching the code as it existed prior to
commit c5b367835c ("MIPS: Add support for XPA.").
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reported-by: Manuel Lauss <manuel.lauss@gmail.com>
Tested-by: Manuel Lauss <manuel.lauss@gmail.com>
Fixes: c5b367835c ("MIPS: Add support for XPA.")
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: stable@vger.kernel.org # v4.1+
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13119/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Ever since support for RI/XI was implemented by commit 6dd9344cfc
("MIPS: Implement Read Inhibit/eXecute Inhibit") we've had a mixture of
_PAGE_READ & _PAGE_NO_READ bits. Rather than keep both around, switch
away from using _PAGE_READ to determine page presence & instead invert
the use to _PAGE_NO_READ. Wherever we formerly had no definition for
_PAGE_NO_READ, change what was _PAGE_READ to _PAGE_NO_READ. The end
result is that we consistently use _PAGE_NO_READ to determine whether a
page is readable, regardless of whether RI/XI is implemented.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13116/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
It's possible for pages to become visible prior to update_mmu_cache
running if a thread within the same address space preempts the current
thread or runs simultaneously on another CPU. That is, the following
scenario is possible:
CPU0 CPU1
write to page
flush_dcache_page
flush_icache_page
set_pte_at
map page
update_mmu_cache
If CPU1 maps the page in between CPU0's set_pte_at, which marks it valid
& visible, and update_mmu_cache where the dcache flush occurs then CPU1s
icache will fill from stale data (unless it fills from the dcache, in
which case all is good, but most MIPS CPUs don't have this property).
Commit 4d46a67a3e ("MIPS: Fix race condition in lazy cache flushing.")
attempted to fix that by performing the dcache flush in
flush_icache_page such that it occurs before the set_pte_at call makes
the page visible. However it has the problem that not all code that
writes to pages exposed to userland call flush_icache_page. There are
many callers of set_pte_at under mm/ and only 2 of them do call
flush_icache_page. Thus the race window between a page becoming visible
& being coherent between the icache & dcache remains open in some cases.
To illustrate some of the cases, a WARN was added to __update_cache with
this patch applied that triggered in cases where a page about to be
flushed from the dcache was not the last page provided to
flush_icache_page. That is, backtraces were obtained for cases in which
the race window is left open without this patch. The 2 standout examples
follow.
When forking a process:
[ 15.271842] [<80417630>] __update_cache+0xcc/0x188
[ 15.277274] [<80530394>] copy_page_range+0x56c/0x6ac
[ 15.282861] [<8042936c>] copy_process.part.54+0xd40/0x17ac
[ 15.289028] [<80429f80>] do_fork+0xe4/0x420
[ 15.293747] [<80413808>] handle_sys+0x128/0x14c
When exec'ing an ELF binary:
[ 14.445964] [<80417630>] __update_cache+0xcc/0x188
[ 14.451369] [<80538d88>] move_page_tables+0x414/0x498
[ 14.457075] [<8055d848>] setup_arg_pages+0x220/0x318
[ 14.462685] [<805b0f38>] load_elf_binary+0x530/0x12a0
[ 14.468374] [<8055ec3c>] search_binary_handler+0xbc/0x214
[ 14.474444] [<8055f6c0>] do_execveat_common+0x43c/0x67c
[ 14.480324] [<8055f938>] do_execve+0x38/0x44
[ 14.485137] [<80413808>] handle_sys+0x128/0x14c
These code paths write into a page, call flush_dcache_page then call
set_pte_at without flush_icache_page inbetween. The end result is that
the icache can become corrupted & userland processes may execute
unexpected or invalid code, typically resulting in a reserved
instruction exception, a trap or a segfault.
Fix this race condition fully by performing any cache maintenance
required to keep the icache & dcache in sync in set_pte_at, before the
page is made valid. This has the added bonus of ensuring the cache
maintenance always happens in one location, rather than being duplicated
in flush_icache_page & update_mmu_cache. It also matches the way other
architectures solve the same problem (see arm, ia64 & powerpc).
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reported-by: Ionela Voinescu <ionela.voinescu@imgtec.com>
Cc: Lars Persson <lars.persson@axis.com>
Fixes: 4d46a67a3e ("MIPS: Fix race condition in lazy cache flushing.")
Cc: Steven J. Hill <sjhill@realitydiluted.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: stable <stable@vger.kernel.org> # v4.1+
Patchwork: https://patchwork.linux-mips.org/patch/12722/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Update the recent changes to set_pte() that were added in 46011e6ea3
to handle R10000_LLSC_WAR, and format the assembly to match other areas
of the MIPS tree using the same WAR.
This also incorporates a patch recently sent in my Markos Chandras,
"Remove local LL/SC preprocessor variants", so that patch doesn't need
to be applied if this one is accepted.
Signed-off-by: Joshua Kinard <kumba@gentoo.org>
Fixes: 46011e6ea3 ("MIPS: Make set_pte() SMP safe.)
Cc: David Daney <david.daney@cavium.com>
Cc: Linux/MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/11103/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Inspired by Markos Chandras' patch. I just didn't want do pull bitsops.h
into pgtable.h.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
References: https://patchwork.linux-mips.org/patch/11052/
Pull MIPS updates from Ralf Baechle:
"This is the main pull request for MIPS for 4.5 plus some 4.4 fixes.
The executive summary:
- ATH79 platform improvments, use DT bindings for the ATH79 USB PHY.
- Avoid useless rebuilds for zboot.
- jz4780: Add NEMC, BCH and NAND device tree nodes
- Initial support for the MicroChip's DT platform. As all the device
drivers are missing this is still of limited use.
- Some Loongson3 cleanups.
- The unavoidable whitespace polishing.
- Reduce clock skew when synchronizing the CPU cycle counters on CPU
startup.
- Add MIPS R6 fixes.
- Lots of cleanups across arch/mips as fallout from KVM.
- Lots of minor fixes and changes for IEEE 754-2008 support to the
FPU emulator / fp-assist software.
- Minor Ralink, BCM47xx and bcm963xx platform support improvments.
- Support SMP on BCM63168"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (84 commits)
MIPS: zboot: Add support for serial debug using the PROM
MIPS: zboot: Avoid useless rebuilds
MIPS: BMIPS: Enable ARCH_WANT_OPTIONAL_GPIOLIB
MIPS: bcm63xx: nvram: Remove unused bcm63xx_nvram_get_psi_size() function
MIPS: bcm963xx: Update bcm_tag field image_sequence
MIPS: bcm963xx: Move extended flash address to bcm_tag header file
MIPS: bcm963xx: Move Broadcom BCM963xx image tag data structure
MIPS: bcm63xx: nvram: Use nvram structure definition from header file
MIPS: bcm963xx: Add Broadcom BCM963xx board nvram data structure
MAINTAINERS: Add KVM for MIPS entry
MIPS: KVM: Add missing newline to kvm_err()
MIPS: Move KVM specific opcodes into asm/inst.h
MIPS: KVM: Use cacheops.h definitions
MIPS: Break down cacheops.h definitions
MIPS: Use EXCCODE_ constants with set_except_vector()
MIPS: Update trap codes
MIPS: Move Cause.ExcCode trap codes to mipsregs.h
MIPS: KVM: Make kvm_mips_{init,exit}() static
MIPS: KVM: Refactor added offsetof()s
MIPS: KVM: Convert EXPORT_SYMBOL to _GPL
...
Commit be0c37c985 (MIPS: Rearrange PTE bits into fixed positions.)
defines fixed PTE bits for MIPS R2. Then, commit d7b631419b
(MIPS: pgtable-bits: Fix XPA damage to R6 definitions.) adds the MIPS
R6 definitions in the same way as MIPS R2. But some R6 #ifdefs in the
later commit are missing, so in this patch I fix that.
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12164/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
With new refcounting we don't need to mark PMDs splitting. Let's drop
code to handle this.
pmdp_splitting_flush() is not needed too: on splitting PMD we will do
pmdp_clear_flush() + set_pte_at(). pmdp_clear_flush() will do IPI as
needed for fast_gup.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If pgprot_writecombine is not #defined, asm-generic/pgtable.h will try
to provide a default implementation by #defining it to pgprot_noncached.
However our implementation is an inline function rather than a #define,
so it was never actually used because of the #define in generic code.
Add "#define pgprot_writecombine pgprot_writecombine" to prevent generic
code from re-defining it.
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10767/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
On MIPS the GLOBAL bit of the PTE must have the same value in any
aligned pair of PTEs. These pairs of PTEs are referred to as
"buddies". In a SMP system is is possible for two CPUs to be calling
set_pte() on adjacent PTEs at the same time. There is a race between
setting the PTE and a different CPU setting the GLOBAL bit in its
buddy PTE.
This race can be observed when multiple CPUs are executing
vmap()/vfree() at the same time.
Make setting the buddy PTE's GLOBAL bit an atomic operation to close
the race condition.
The case of CONFIG_64BIT_PHYS_ADDR && CONFIG_CPU_MIPS32 is *not*
handled.
Signed-off-by: David Daney <david.daney@cavium.com>
Cc: <stable@vger.kernel.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10835/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
We have confusing functions to clear pmd, pmd_clear_* and pmd_clear. Add
_huge_ to pmdp_clear functions so that we are clear that they operate on
hugepage pte.
We don't bother about other functions like pmdp_set_wrprotect,
pmdp_clear_flush_young, because they operate on PTE bits and hence
indicate they are operating on hugepage ptes
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add support for extended physical addressing (XPA) so that
32-bit platforms can access equal to or greater than 40 bits
of physical addresses.
NOTE:
1) XPA and EVA are not the same and cannot be used
simultaneously.
2) If you configure your kernel for XPA, the PTEs
and all address sizes become 64-bit.
3) Your platform MUST have working HIGHMEM support.
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9355/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This patch rearranges the PTE bits into fixed positions for R2
and later cores. In the past, the TLB handling code did runtime
checking of RI/XI and adjusted the shifts and rotates in order
to fit the largest PFN value into the PTE. The checking now
occurs when building the TLB handler, thus eliminating those
checks. These new arrangements also define the largest possible
PFN value that can fit in the PTE. HUGE page support is only
available for 64-bit cores. Layouts of the PTE bits are now:
64-bit, R1 or earlier: CCC D V G [S H] M A W R P
32-bit, R1 or earler: CCC D V G M A W R P
64-bit, R2 or later: CCC D V G RI/R XI [S H] M A W P
32-bit, R2 or later: CCC D V G RI/R XI M A W P
[ralf@linux-mips.org: Fix another build error *rant* *rant*]
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9353/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull MIPS updates from Ralf Baechle:
"This is the main pull request for MIPS:
- a number of fixes that didn't make the 3.19 release.
- a number of cleanups.
- preliminary support for Cavium's Octeon 3 SOCs which feature up to
48 MIPS64 R3 cores with FPU and hardware virtualization.
- support for MIPS R6 processors.
Revision 6 of the MIPS architecture is a major revision of the MIPS
architecture which does away with many of original sins of the
architecture such as branch delay slots. This and other changes in
R6 require major changes throughout the entire MIPS core
architecture code and make up for the lion share of this pull
request.
- finally some preparatory work for eXtendend Physical Address
support, which allows support of up to 40 bit of physical address
space on 32 bit processors"
[ Ahh, MIPS can't leave the PAE brain damage alone. It's like
every CPU architect has to make that mistake, but pee in the snow
by changing the TLA. But whether it's called PAE, LPAE or XPA,
it's horrid crud - Linus ]
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (114 commits)
MIPS: sead3: Corrected get_c0_perfcount_int
MIPS: mm: Remove dead macro definitions
MIPS: OCTEON: irq: add CIB and other fixes
MIPS: OCTEON: Don't do acknowledge operations for level triggered irqs.
MIPS: OCTEON: More OCTEONIII support
MIPS: OCTEON: Remove setting of processor specific CVMCTL icache bits.
MIPS: OCTEON: Core-15169 Workaround and general CVMSEG cleanup.
MIPS: OCTEON: Update octeon-model.h code for new SoCs.
MIPS: OCTEON: Implement DCache errata workaround for all CN6XXX
MIPS: OCTEON: Add little-endian support to asm/octeon/octeon.h
MIPS: OCTEON: Implement the core-16057 workaround
MIPS: OCTEON: Delete unused COP2 saving code
MIPS: OCTEON: Use correct instruction to read 64-bit COP0 register
MIPS: OCTEON: Save and restore CP2 SHA3 state
MIPS: OCTEON: Fix FP context save.
MIPS: OCTEON: Save/Restore wider multiply registers in OCTEON III CPUs
MIPS: boot: Provide more uImage options
MIPS: Remove unneeded #ifdef __KERNEL__ from asm/processor.h
MIPS: ip22-gio: Remove legacy suspend/resume support
mips: pci: Add ifdef around pci_proc_domain
...
* Clean up white spaces and tabs.
* Get rid of remaining hardcoded values for calculating
shifts and masks.
* Get rid of redundant macro values.
* Do not use page table bits directly in #ifdef's.
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9287/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
activate_mm() and switch_mm() call get_new_mmu_context() which in turn
can enable the HTW before the entryhi is changed with the new ASID.
Since the latter will enable the HTW in local_flush_tlb_all(),
then there is a small timing window where the HTW is running with the
new ASID but with an old pgd since the TLBMISS_HANDLER_SETUP_PGD
hasn't assigned a new one yet. In order to prevent that, we introduce a
simple htw counter to avoid starting HTW accidentally due to nested
htw_{start,stop}() sequences. Moreover, since various IPI calls can
enforce TLB flushing operations on a different core, such an operation
may interrupt another htw_{stop,start} in progress leading inconsistent
updates of the htw_seq variable. In order to avoid that, we disable the
interrupts whenever we update that variable.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 3.17+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9118/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Whenever we modify a page table entry, we need to ensure that the HTW
will not fetch a stable entry. And for that to happen we need to ensure
that HTW is stopped before we modify the said entry otherwise the HTW
may already be in the process of reading that entry and fetching the
old information. As a result of which, we replace the htw_reset() calls
with htw_{stop,start} in more appropriate places. This also removes the
remaining users of htw_reset() and as a result we drop that macro
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 3.17+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9116/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
When we use htw_{start,stop}() outside of htw_reset(), we need
to ensure that c0 changes have been propagated properly before
we attempt to continue with subsequence memory operations.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 3.17+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9114/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* Clean up white spaces and tabs.
* Remove _PAGE_R4KBUG which is no longer used.
* Get rid of hardcoded values and calculate shifts and
masks where possible.
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8457/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Previously, the pgprot_writecombine function was simply defined
as pgprot_uncached in include/asm-generic/pgtable.h. This is not
optimal for cores that can actually do write-combine memory writes
so define this function to take into account the core's cache coherency
attribute to achieve such behavior.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7403/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Multicore MIPSes without I/D hardware coherency suffered from a race
condition in the page fault handler. The page table entry was
published before any pending lazy D-cache flush was committed, hence
it allowed execution of stale page cache data by other VPEs in the
system.
To make the cache handling safe we need to perform flushing already in
the set_pte_at function. MIPSes without coherent I-caches can get a
small increase in flushes due to the unavailability of the execute
flag in set_pte_at.
[ralf@linux-mips.org: outlining set_pte_at() saves a good k in a test
build, so I moved its definition from pgtable.h to cache.c.]
Signed-off-by: Lars Persson <larper@axis.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7511/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The Hardware Page Table Walker aims to speed up TLB refill exceptions
by handling them in the hardware level instead of having a software
TLB refill handler. However, a TLB refill exception can still be
thrown in certain cases such as, synchronus exceptions, or address
translation or memory errors during the HTW operation. As a result of
which, HTW must not be considered a complete replacement for the TLB
refill software handler, but rather a fast-path for it.
For HTW to work, the PWBase register must contain the task's page
global directory address so the HTW will kick in on TLB refill
exceptions.
Due to HTW being a separate engine embedded deep in the CPU pipeline,
we need to restart the HTW everytime a PTE changes to avoid HTW
fetching a old entry from the page tables. It's also necessary to
restart the HTW on context switches to prevent it from fetching a
page from the previous process. Finally, since HTW is using the
entryhi register to write the translations to the TLB, it's necessary
to stop the HTW whenever the entryhi changes (eg for tlb probe
perations) and enable it back afterwards.
== Performance ==
The following trivial test was used to measure the performance of the
HTW. Using the same root filesystem, the following command was used
to measure the number of tlb refill handler executions with and
without (using 'nohtw' kernel parameter) HTW support. The kernel was
modified to use a scratch register as a counter for the TLB refill
exceptions.
find /usr -type f -exec ls -lh {} \;
HTW Enabled:
TLB refill exceptions: 12306
HTW Disabled:
TLB refill exceptions: 17805
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/7336/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This is identical to kmap_coherent apart from the cache coherency
attribute used for the TLB entry, so kmap_coherent is abstracted to
kmap_prot which is then called for both kmap_coherent &
kmap_noncoherent. This will be used by a subsequent patch.
Suggested-by: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
With the addition of transparent huge pages, pgtable.h uses struct page.
However, it is possible to include pgtable.h without anything defining
struct page. So add the include to get it.
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Having received another series of whitespace patches I decided to do this
once and for all rather than dealing with this kind of patches trickling
in forever.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull MIPS updates from Ralf Baechle:
"The MIPS bits for 3.8. This also includes a bunch fixes that were
sitting in the linux-mips.org git tree for a long time. This pull
request contains updates to several OCTEON drivers and the board
support code for BCM47XX, BCM63XX, XLP, XLR, XLS, lantiq, Loongson1B,
updates to the SSB bus support, MIPS kexec code and adds support for
kdump.
When pulling this, there are two expected merge conflicts in
include/linux/bcma/bcma_driver_chipcommon.h which are trivial to
resolve, just remove the conflict markers and keep both alternatives."
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (90 commits)
MIPS: PMC-Sierra Yosemite: Remove support.
VIDEO: Newport Fix console crashes
MIPS: wrppmc: Fix build of PCI code.
MIPS: IP22/IP28: Fix build of EISA code.
MIPS: RB532: Fix build of prom code.
MIPS: PowerTV: Fix build.
MIPS: IP27: Correct fucked grammar in ops-bridge.c
MIPS: Highmem: Fix build error if CONFIG_DEBUG_HIGHMEM is disabled
MIPS: Fix potencial corruption
MIPS: Fix for warning from FPU emulation code
MIPS: Handle COP3 Unusable exception as COP1X for FP emulation
MIPS: Fix poweroff failure when HOTPLUG_CPU configured.
MIPS: MT: Fix build with CONFIG_UIDGID_STRICT_TYPE_CHECKS=y
MIPS: Remove unused smvp.h
MIPS/EDAC: Improve OCTEON EDAC support.
MIPS: OCTEON: Add definitions for OCTEON memory contoller registers.
MIPS: OCTEON: Add OCTEON family definitions to octeon-model.h
ata: pata_octeon_cf: Use correct byte order for DMA in when built little-endian.
MIPS/OCTEON/ata: Convert pata_octeon_cf.c to use device tree.
MIPS: Remove usage of CEVT_R4K_LIB config option.
...
We have two different implementation of is_zero_pfn() and my_zero_pfn()
helpers: for architectures with and without zero page coloring.
Let's consolidate them in <asm-generic/pgtable.h>.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mike Rapoport