linux-stable.git/arch/arc, branch v4.9.142 Linux kernel stable tree ARC: build: Don't set CROSS_COMPILE in arch's Makefile 2018-10-20T07:51:32+00:00 Alexey Brodkin abrodkin@synopsys.com 2018-09-16T20:47:57+00:00 5d4c6663ebf6988bdb67676436234041ba715585 commit 40660f1fcee8d524a60b5101538e42b1f39f106d upstream. There's not much sense in doing that because if user or his build-system didn't set CROSS_COMPILE we still may very well make incorrect guess. But as it turned out setting CROSS_COMPILE is not as harmless as one may think: with recent changes that implemented automatic discovery of __host__ gcc features unconditional setup of CROSS_COMPILE leads to failures on execution of "make xxx_defconfig" with absent cross-compiler, for more info see [1]. Set CROSS_COMPILE as well gets in the way if we want only to build .dtb's (again with absent cross-compiler which is not really needed for building .dtb's), see [2]. Note, we had to change LIBGCC assignment type from ":=" to "=" so that is is resolved on its usage, otherwise if it is resolved at declaration time with missing CROSS_COMPILE we're getting this error message from host GCC: | gcc: error: unrecognized command line option -mmedium-calls | gcc: error: unrecognized command line option -mno-sdata [1] http://lists.infradead.org/pipermail/linux-snps-arc/2018-September/004308.html [2] http://lists.infradead.org/pipermail/linux-snps-arc/2018-September/004320.html Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Rob Herring <robh@kernel.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 40660f1fcee8d524a60b5101538e42b1f39f106d upstream.

There's not much sense in doing that because if user or
his build-system didn't set CROSS_COMPILE we still may
very well make incorrect guess.

But as it turned out setting CROSS_COMPILE is not as harmless
as one may think: with recent changes that implemented automatic
discovery of __host__ gcc features unconditional setup of
CROSS_COMPILE leads to failures on execution of "make xxx_defconfig"
with absent cross-compiler, for more info see [1].

Set CROSS_COMPILE as well gets in the way if we want only to build
.dtb's (again with absent cross-compiler which is not really needed
for building .dtb's), see [2].

Note, we had to change LIBGCC assignment type from ":=" to "="
so that is is resolved on its usage, otherwise if it is resolved
at declaration time with missing CROSS_COMPILE we're getting this
error message from host GCC:

| gcc: error: unrecognized command line option -mmedium-calls
| gcc: error: unrecognized command line option -mno-sdata

[1] http://lists.infradead.org/pipermail/linux-snps-arc/2018-September/004308.html
[2] http://lists.infradead.org/pipermail/linux-snps-arc/2018-September/004320.html

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARC: build: Get rid of toolchain check 2018-10-20T07:51:32+00:00 Alexey Brodkin abrodkin@synopsys.com 2018-09-13T20:24:28+00:00 e4450e391ae3fc706f0910cefae0904f75f7595c commit 615f64458ad890ef94abc879a66d8b27236e733a upstream. This check is very naive: we simply test if GCC invoked without "-mcpu=XXX" has ARC700 define set. In that case we think that GCC was built with "--with-cpu=arc700" and has libgcc built for ARC700. Otherwise if ARC700 is not defined we think that everythng was built for ARCv2. But in reality our life is much more interesting. 1. Regardless of GCC configuration (i.e. what we pass in "--with-cpu" it may generate code for any ARC core). 2. libgcc might be built with explicitly specified "--mcpu=YYY" That's exactly what happens in case of multilibbed toolchains: - GCC is configured with default settings - All the libs built for many different CPU flavors I.e. that check gets in the way of usage of multilibbed toolchains. And even non-multilibbed toolchains are affected. OpenEmbedded also builds GCC without "--with-cpu" because each and every target component later is compiled with explicitly set "-mcpu=ZZZ". Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 615f64458ad890ef94abc879a66d8b27236e733a upstream.

This check is very naive: we simply test if GCC invoked without
"-mcpu=XXX" has ARC700 define set. In that case we think that GCC
was built with "--with-cpu=arc700" and has libgcc built for ARC700.

Otherwise if ARC700 is not defined we think that everythng was built
for ARCv2.

But in reality our life is much more interesting.

1. Regardless of GCC configuration (i.e. what we pass in "--with-cpu"
   it may generate code for any ARC core).

2. libgcc might be built with explicitly specified "--mcpu=YYY"

That's exactly what happens in case of multilibbed toolchains:
 - GCC is configured with default settings
 - All the libs built for many different CPU flavors

I.e. that check gets in the way of usage of multilibbed
toolchains. And even non-multilibbed toolchains are affected.
OpenEmbedded also builds GCC without "--with-cpu" because
each and every target component later is compiled with explicitly
set "-mcpu=ZZZ".

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARC: clone syscall to setp r25 as thread pointer 2018-10-13T07:18:57+00:00 Vineet Gupta vgupta@synopsys.com 2018-10-05T19:48:48+00:00 e82f7903a6b55e673297e6bccce120569c7426e4 commit c58a584f05e35d1d4342923cd7aac07d9c3d3d16 upstream. Per ARC TLS ABI, r25 is designated TP (thread pointer register). However so far kernel didn't do any special treatment, like setting up usermode r25, even for CLONE_SETTLS. We instead relied on libc runtime to do this, in say clone libc wrapper [1]. This was deliberate to keep kernel ABI agnostic (userspace could potentially change TP, specially for different ARC ISA say ARCompact vs. ARCv2 with different spare registers etc) However userspace setting up r25, after clone syscall opens a race, if child is not scheduled and gets a signal instead. It starts off in userspace not in clone but in a signal handler and anything TP sepcific there such as pthread_self() fails which showed up with uClibc testsuite nptl/tst-kill6 [2] Fix this by having kernel populate r25 to TP value. So this locks in ABI, but it was not going to change anyways, and fwiw is same for both ARCompact (arc700 core) and ARCvs (HS3x cores) [1] https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/tree/libc/sysdeps/linux/arc/clone.S [2] https://github.com/wbx-github/uclibc-ng-test/blob/master/test/nptl/tst-kill6.c Fixes: ARC STAR 9001378481 Cc: stable@vger.kernel.org Reported-by: Nikita Sobolev <sobolev@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c58a584f05e35d1d4342923cd7aac07d9c3d3d16 upstream.

Per ARC TLS ABI, r25 is designated TP (thread pointer register).
However so far kernel didn't do any special treatment, like setting up
usermode r25, even for CLONE_SETTLS. We instead relied on libc runtime
to do this, in say clone libc wrapper [1]. This was deliberate to keep
kernel ABI agnostic (userspace could potentially change TP, specially
for different ARC ISA say ARCompact vs. ARCv2 with different spare
registers etc)

However userspace setting up r25, after clone syscall opens a race, if
child is not scheduled and gets a signal instead. It starts off in
userspace not in clone but in a signal handler and anything TP sepcific
there such as pthread_self() fails which showed up with uClibc
testsuite nptl/tst-kill6 [2]

Fix this by having kernel populate r25 to TP value. So this locks in
ABI, but it was not going to change anyways, and fwiw is same for both
ARCompact (arc700 core) and ARCvs (HS3x cores)

[1] https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/tree/libc/sysdeps/linux/arc/clone.S
[2] https://github.com/wbx-github/uclibc-ng-test/blob/master/test/nptl/tst-kill6.c

Fixes: ARC STAR 9001378481
Cc: stable@vger.kernel.org
Reported-by: Nikita Sobolev <sobolev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARC: atomics: unbork atomic_fetch_##op() 2018-10-10T06:53:18+00:00 Will Deacon will.deacon@arm.com 2018-08-30T20:52:38+00:00 a0890a027250aea86e0758f8f3c0a74fb084beb8 [ Upstream commit 3fcbb8260a87efb691d837e8cd24e81f65b3eb70 ] In 4.19-rc1, Eugeniy reported weird boot and IO errors on ARC HSDK | INFO: task syslogd:77 blocked for more than 10 seconds. | Not tainted 4.19.0-rc1-00007-gf213acea4e88 #40 | "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this | message. | syslogd D 0 77 76 0x00000000 | | Stack Trace: | __switch_to+0x0/0xac | __schedule+0x1b2/0x730 | io_schedule+0x5c/0xc0 | __lock_page+0x98/0xdc | find_lock_entry+0x38/0x100 | shmem_getpage_gfp.isra.3+0x82/0xbfc | shmem_fault+0x46/0x138 | handle_mm_fault+0x5bc/0x924 | do_page_fault+0x100/0x2b8 | ret_from_exception+0x0/0x8 He bisected to 84c6591103db ("locking/atomics, asm-generic/bitops/lock.h: Rewrite using atomic_fetch_*()") This commit however only unmasked the real issue introduced by commit 4aef66c8ae9 ("locking/atomic, arch/arc: Fix build") which missed the retry-if-scond-failed branch in atomic_fetch_##op() macros. The bisected commit started using atomic_fetch_##op() macros for building the rest of atomics. Fixes: 4aef66c8ae9 ("locking/atomic, arch/arc: Fix build") Reported-by: Eugeniy Paltsev <paltsev@synopsys.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> [vgupta: wrote changelog] Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 3fcbb8260a87efb691d837e8cd24e81f65b3eb70 ]

In 4.19-rc1, Eugeniy reported weird boot and IO errors on ARC HSDK

| INFO: task syslogd:77 blocked for more than 10 seconds.
|       Not tainted 4.19.0-rc1-00007-gf213acea4e88 #40
| "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
| message.
| syslogd         D    0    77     76 0x00000000
|
| Stack Trace:
|  __switch_to+0x0/0xac
|  __schedule+0x1b2/0x730
|  io_schedule+0x5c/0xc0
|  __lock_page+0x98/0xdc
|  find_lock_entry+0x38/0x100
|  shmem_getpage_gfp.isra.3+0x82/0xbfc
|  shmem_fault+0x46/0x138
|  handle_mm_fault+0x5bc/0x924
|  do_page_fault+0x100/0x2b8
|  ret_from_exception+0x0/0x8

He bisected to 84c6591103db ("locking/atomics,
asm-generic/bitops/lock.h: Rewrite using atomic_fetch_*()")

This commit however only unmasked the real issue introduced by commit
4aef66c8ae9 ("locking/atomic, arch/arc: Fix build") which missed the
retry-if-scond-failed branch in atomic_fetch_##op() macros.

The bisected commit started using atomic_fetch_##op() macros for building
the rest of atomics.

Fixes: 4aef66c8ae9 ("locking/atomic, arch/arc: Fix build")
Reported-by: Eugeniy Paltsev <paltsev@synopsys.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: wrote changelog]
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARC: [plat-axs*]: Enable SWAP 2018-09-19T20:47:12+00:00 Alexey Brodkin abrodkin@synopsys.com 2018-08-02T08:50:16+00:00 3b21adca3d1513f8996c7623596b329fc418a0a4 commit c83532fb0fe053d2e43e9387354cb1b52ba26427 upstream. SWAP support on ARC was fixed earlier by commit 6e3761145a9b ("ARC: Fix CONFIG_SWAP") so now we may safely enable it on platforms that have external media like USB and SD-card. Note: it was already allowed for HSDK Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Cc: stable@vger.kernel.org # 6e3761145a9b: ARC: Fix CONFIG_SWAP Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c83532fb0fe053d2e43e9387354cb1b52ba26427 upstream.

SWAP support on ARC was fixed earlier by
commit 6e3761145a9b ("ARC: Fix CONFIG_SWAP")
so now we may safely enable it on platforms that
have external media like USB and SD-card.

Note: it was already allowed for HSDK

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: stable@vger.kernel.org # 6e3761145a9b: ARC: Fix CONFIG_SWAP
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arc: fix type warnings in arc/mm/cache.c 2018-09-05T07:20:03+00:00 Randy Dunlap rdunlap@infradead.org 2018-07-27T03:16:35+00:00 8620db886d78954e656a47320f5d3593efac992d [ Upstream commit ec837d620c750c0d4996a907c8c4f7febe1bbeee ] Fix type warnings in arch/arc/mm/cache.c. ../arch/arc/mm/cache.c: In function 'flush_anon_page': ../arch/arc/mm/cache.c:1062:55: warning: passing argument 2 of '__flush_dcache_page' makes integer from pointer without a cast [-Wint-conversion] __flush_dcache_page((phys_addr_t)page_address(page), page_address(page)); ^~~~~~~~~~~~~~~~~~ ../arch/arc/mm/cache.c:1013:59: note: expected 'long unsigned int' but argument is of type 'void *' void __flush_dcache_page(phys_addr_t paddr, unsigned long vaddr) ~~~~~~~~~~~~~~^~~~~ Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: linux-snps-arc@lists.infradead.org Cc: Elad Kanfi <eladkan@mellanox.com> Cc: Leon Romanovsky <leonro@mellanox.com> Cc: Ofer Levi <oferle@mellanox.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit ec837d620c750c0d4996a907c8c4f7febe1bbeee ]

Fix type warnings in arch/arc/mm/cache.c.

../arch/arc/mm/cache.c: In function 'flush_anon_page':
../arch/arc/mm/cache.c:1062:55: warning: passing argument 2 of '__flush_dcache_page' makes integer from pointer without a cast [-Wint-conversion]
  __flush_dcache_page((phys_addr_t)page_address(page), page_address(page));
                                                       ^~~~~~~~~~~~~~~~~~
../arch/arc/mm/cache.c:1013:59: note: expected 'long unsigned int' but argument is of type 'void *'
 void __flush_dcache_page(phys_addr_t paddr, unsigned long vaddr)
                                             ~~~~~~~~~~~~~~^~~~~

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: linux-snps-arc@lists.infradead.org
Cc: Elad Kanfi <eladkan@mellanox.com>
Cc: Leon Romanovsky <leonro@mellanox.com>
Cc: Ofer Levi <oferle@mellanox.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arc: fix build errors in arc/include/asm/delay.h 2018-09-05T07:20:03+00:00 Randy Dunlap rdunlap@infradead.org 2018-07-27T03:16:35+00:00 6e64609123832dfa093ae8cce3d15d116ab3383c [ Upstream commit 2423665ec53f2a29191b35382075e9834288a975 ] Fix build errors in arch/arc/'s delay.h: - add "extern unsigned long loops_per_jiffy;" - add <asm-generic/types.h> for "u64" In file included from ../drivers/infiniband/hw/cxgb3/cxio_hal.c:32: ../arch/arc/include/asm/delay.h: In function '__udelay': ../arch/arc/include/asm/delay.h:61:12: error: 'u64' undeclared (first use in this function) loops = ((u64) usecs * 4295 * HZ * loops_per_jiffy) >> 32; ^~~ In file included from ../drivers/infiniband/hw/cxgb3/cxio_hal.c:32: ../arch/arc/include/asm/delay.h: In function '__udelay': ../arch/arc/include/asm/delay.h:63:37: error: 'loops_per_jiffy' undeclared (first use in this function) loops = ((u64) usecs * 4295 * HZ * loops_per_jiffy) >> 32; ^~~~~~~~~~~~~~~ Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: linux-snps-arc@lists.infradead.org Cc: Elad Kanfi <eladkan@mellanox.com> Cc: Leon Romanovsky <leonro@mellanox.com> Cc: Ofer Levi <oferle@mellanox.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 2423665ec53f2a29191b35382075e9834288a975 ]

Fix build errors in arch/arc/'s delay.h:
- add "extern unsigned long loops_per_jiffy;"
- add <asm-generic/types.h> for "u64"

In file included from ../drivers/infiniband/hw/cxgb3/cxio_hal.c:32:
../arch/arc/include/asm/delay.h: In function '__udelay':
../arch/arc/include/asm/delay.h:61:12: error: 'u64' undeclared (first use in this function)
  loops = ((u64) usecs * 4295 * HZ * loops_per_jiffy) >> 32;
            ^~~

In file included from ../drivers/infiniband/hw/cxgb3/cxio_hal.c:32:
../arch/arc/include/asm/delay.h: In function '__udelay':
../arch/arc/include/asm/delay.h:63:37: error: 'loops_per_jiffy' undeclared (first use in this function)
  loops = ((u64) usecs * 4295 * HZ * loops_per_jiffy) >> 32;
                                     ^~~~~~~~~~~~~~~

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: linux-snps-arc@lists.infradead.org
Cc: Elad Kanfi <eladkan@mellanox.com>
Cc: Leon Romanovsky <leonro@mellanox.com>
Cc: Ofer Levi <oferle@mellanox.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arc: [plat-eznps] fix data type errors in platform headers 2018-09-05T07:20:03+00:00 Randy Dunlap rdunlap@infradead.org 2018-07-29T18:10:51+00:00 fcc80f8ed96db26ffbf4a7c5049b7e99b0bcedbe [ Upstream commit b1f32ce1c3d2c11959b7e6a2c58dc5197c581966 ] Add <linux/types.h> to fix build errors. Both ctop.h and <soc/nps/common.h> use u32 types and cause many errors. Examples: ../include/soc/nps/common.h:71:4: error: unknown type name 'u32' u32 __reserved:20, cluster:4, core:4, thread:4; ../include/soc/nps/common.h:76:3: error: unknown type name 'u32' u32 value; ../include/soc/nps/common.h:124:4: error: unknown type name 'u32' u32 base:8, cl_x:4, cl_y:4, ../include/soc/nps/common.h:127:3: error: unknown type name 'u32' u32 value; ../arch/arc/plat-eznps/include/plat/ctop.h:83:4: error: unknown type name 'u32' u32 gen:1, gdis:1, clk_gate_dis:1, asb:1, ../arch/arc/plat-eznps/include/plat/ctop.h:86:3: error: unknown type name 'u32' u32 value; ../arch/arc/plat-eznps/include/plat/ctop.h:93:4: error: unknown type name 'u32' u32 csa:22, dmsid:6, __reserved:3, cs:1; ../arch/arc/plat-eznps/include/plat/ctop.h:95:3: error: unknown type name 'u32' u32 value; Cc: linux-snps-arc@lists.infradead.org Cc: Ofer Levi <oferle@mellanox.com> Reviewed-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit b1f32ce1c3d2c11959b7e6a2c58dc5197c581966 ]

Add <linux/types.h> to fix build errors.
Both ctop.h and <soc/nps/common.h> use u32 types and cause many
errors.

Examples:
../include/soc/nps/common.h:71:4: error: unknown type name 'u32'
    u32 __reserved:20, cluster:4, core:4, thread:4;
../include/soc/nps/common.h:76:3: error: unknown type name 'u32'
   u32 value;
../include/soc/nps/common.h:124:4: error: unknown type name 'u32'
    u32 base:8, cl_x:4, cl_y:4,
../include/soc/nps/common.h:127:3: error: unknown type name 'u32'
   u32 value;

../arch/arc/plat-eznps/include/plat/ctop.h:83:4: error: unknown type name 'u32'
    u32 gen:1, gdis:1, clk_gate_dis:1, asb:1,
../arch/arc/plat-eznps/include/plat/ctop.h:86:3: error: unknown type name 'u32'
   u32 value;
../arch/arc/plat-eznps/include/plat/ctop.h:93:4: error: unknown type name 'u32'
    u32 csa:22, dmsid:6, __reserved:3, cs:1;
../arch/arc/plat-eznps/include/plat/ctop.h:95:3: error: unknown type name 'u32'
   u32 value;

Cc: linux-snps-arc@lists.infradead.org
Cc: Ofer Levi <oferle@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARC: Improve cmpxchg syscall implementation 2018-08-24T11:12:37+00:00 Peter Zijlstra peterz@infradead.org 2018-06-19T14:22:05+00:00 6cfe79de46e812aa83aabc1e97cb6d0ebaa793da [ Upstream commit e8708786d4fe21c043d38d760f768949a3d71185 ] This is used in configs lacking hardware atomics to emulate atomic r-m-w for user space, implemented by disabling preemption in kernel. However there are issues in current implementation: 1. Process not terminated if invalid user pointer passed: i.e. __get_user() failed. 2. The reason for this patch was __put_user() failure not being handled either, specifically for the COW break scenario. The zero page is initially wired up and read from __get_user() succeeds. A subsequent write by __put_user() induces a Protection Violation, but COW can't finish as Linux page fault handler is disabled due to preempt disable. And what's worse is we silently return the stale value to user space. Fix this specific case by re-enabling preemption and explicitly fixing up the fault and retrying the whole sequence over. Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: linux-arch@vger.kernel.org Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> [vgupta: rewrote the changelog] Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit e8708786d4fe21c043d38d760f768949a3d71185 ]

This is used in configs lacking hardware atomics to emulate atomic r-m-w
for user space, implemented by disabling preemption in kernel.

However there are issues in current implementation:

1. Process not terminated if invalid user pointer passed:
   i.e. __get_user() failed.

2. The reason for this patch was __put_user() failure not being handled
   either, specifically for the COW break scenario.
   The zero page is initially wired up and read from __get_user()
   succeeds. A subsequent write by __put_user() induces a
   Protection Violation, but COW can't finish as Linux page fault
   handler is disabled due to preempt disable.
   And what's worse is we silently return the stale value to user space.
   Fix this specific case by re-enabling preemption and explicitly
   fixing up the fault and retrying the whole sequence over.

Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-arch@vger.kernel.org
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: rewrote the changelog]
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARC: Enable machine_desc->init_per_cpu for !CONFIG_SMP 2018-08-24T11:12:30+00:00 Alexey Brodkin Alexey.Brodkin@synopsys.com 2017-11-29T08:21:45+00:00 8cc70515536870ebcd9d81c54fc4d6451e4e6912 [ Upstream commit 2f24ef7413a4d91657ef04e77c27ce0b313e6c95 ] machine_desc->init_per_cpu() hook is supposed to be per cpu initialization and would seem to apply equally to UP and/or SMP. Infact the comment in header file seems to suggest it works for UP too, which was not the case and this patch. This enables !CONFIG_SMP build for platforms such as hsdk. Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> [vgupta: trimmeed changelog] Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 2f24ef7413a4d91657ef04e77c27ce0b313e6c95 ]

machine_desc->init_per_cpu() hook is supposed to be per cpu
initialization and would seem to apply  equally to UP and/or SMP.
Infact the comment in header file seems to suggest it works for
UP too, which was not the case and this patch.

This enables !CONFIG_SMP build for platforms such as hsdk.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: trimmeed changelog]
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>