The default value of ARCH_SLAB_MINALIGN in "include/linux/slab.h" is
"__alignof__(unsigned long long)" which for ARC unexpectedly turns out
to be 4. This is not a compiler bug, but as defined by ARC ABI [1]
Thus slab allocator would allocate a struct which is 32-bit aligned,
which is generally OK even if struct has long long members.
There was however potetial problem when it had any atomic64_t which
use LLOCKD/SCONDD instructions which are required by ISA to take
64-bit addresses. This is the problem we ran into
[ 4.015732] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[ 4.167881] Misaligned Access
[ 4.172356] Path: /bin/busybox.nosuid
[ 4.176004] CPU: 2 PID: 171 Comm: rm Not tainted 4.19.14-yocto-standard #1
[ 4.182851]
[ 4.182851] [ECR ]: 0x000d0000 => Check Programmer's Manual
[ 4.190061] [EFA ]: 0xbeaec3fc
[ 4.190061] [BLINK ]: ext4_delete_entry+0x210/0x234
[ 4.190061] [ERET ]: ext4_delete_entry+0x13e/0x234
[ 4.202985] [STAT32]: 0x80080002 : IE K
[ 4.207236] BTA: 0x9009329c SP: 0xbe5b1ec4 FP: 0x00000000
[ 4.212790] LPS: 0x9074b118 LPE: 0x9074b120 LPC: 0x00000000
[ 4.218348] r00: 0x00000040 r01: 0x00000021 r02: 0x00000001
...
...
[ 4.270510] Stack Trace:
[ 4.274510] ext4_delete_entry+0x13e/0x234
[ 4.278695] ext4_rmdir+0xe0/0x238
[ 4.282187] vfs_rmdir+0x50/0xf0
[ 4.285492] do_rmdir+0x9e/0x154
[ 4.288802] EV_Trap+0x110/0x114
The fix is to make sure slab allocations are 64-bit aligned.
Do note that atomic64_t is __attribute__((aligned(8)) which means gcc
does generate 64-bit aligned references, relative to beginning of
container struct. However the issue is if the container itself is not
64-bit aligned, atomic64_t ends up unaligned which is what this patch
ensures.
[1] https://github.com/foss-for-synopsys-dwc-arc-processors/toolchain/wiki/files/ARCv2_ABI.pdf
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: <stable@vger.kernel.org> # 4.8+
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: reworked changelog, added dependency on LL64+LLSC]
If IOC was already enabled (due to bootloader) it technically needs to
be reconfigured with aperture base,size corresponding to Linux memory map
which will certainly be different than uboot's. But disabling and
reenabling IOC when DMA might be potentially active is tricky business.
To avoid random memory issues later, just panic here and ask user to
upgrade bootloader to one which doesn't enable IOC
This was actually seen as issue on some of the HSDK board with a version
of uboot which enabled IOC. There were random issues later with starting
of X or peripherals etc.
Also while I'm at it, replace hardcoded bits in ARC_REG_IO_COH_PARTIAL
and ARC_REG_IO_COH_ENABLE registers by definitions.
Inspired by: https://lkml.org/lkml/2018/1/19/557
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
As for today we don't setup SMP_CACHE_BYTES and cache_line_size for
ARC, so they are set to L1_CACHE_BYTES by default. L1 line length
(L1_CACHE_BYTES) might be easily smaller than L2 line (which is
usually the case BTW). This breaks code.
For example this breaks ethernet infrastructure on HSDK/AXS103 boards
with IOC disabled, involving manual cache flushes
Functions which alloc and manage sk_buff packet data area rely on
SMP_CACHE_BYTES define. In the result we can share last L2 cache
line in sk_buff linear packet data area between DMA buffer and
some useful data in other structure. So we can lose this data when
we invalidate DMA buffer.
sk_buff linear packet data area
|
|
| skb->end skb->tail
V | |
V V
----------------------------------------------.
packet data | <tail padding> | <useful data in other struct>
----------------------------------------------.
---------------------.--------------------------------------------------.
SLC line | SLC (L2 cache) line (128B) |
---------------------.--------------------------------------------------.
^ ^
| |
These cache lines will be invalidated when we invalidate skb
linear packet data area before DMA transaction starting.
This leads to issues painful to debug as it reproduces only if
(sk_buff->end - sk_buff->tail) < SLC_LINE_SIZE and
if we have some useful data right after sk_buff->end.
Fix that by hardcode SMP_CACHE_BYTES to max line length we may have.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Current implementation relies on L1 line length which might easily
be smaller than L2 line (which is usually the case BTW).
Imagine this typical case: L2 line is 128 bytes while L1 line is
64-bytes. Now we want to allocate small buffer and later use it for DMA
(consider IOC is not available).
kmalloc() allocates small KMALLOC_MIN_SIZE-sized, KMALLOC_MIN_SIZE-aligned
That way if buffer happens to be aligned to L1 line and not L2 line we'll be
flushing and invalidating extra portions of data from L2 which will cause
cache coherency issues.
And since KMALLOC_MIN_SIZE is bound to ARCH_DMA_MINALIGN the fix could
be simple - set ARCH_DMA_MINALIGN to the largest cache line we may ever
get. As of today neither L1 of ARC700 and ARC HS38 nor SLC might not be
longer than 128 bytes.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
It is necessary to explicitly set both SLC_AUX_RGN_START1 and SLC_AUX_RGN_END1
which hold MSB bits of the physical address correspondingly of region start
and end otherwise SLC region operation is executed in unpredictable manner
Without this patch, SLC flushes on HSDK (IOC disabled) were taking
seconds.
Cc: stable@vger.kernel.org #4.4+
Reported-by: Vladimir Kondratiev <vladimir.kondratiev@intel.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: PAR40 regs only written if PAE40 exist]
DC_CTRL.RGN_OP is 3 bits wide, however only 1 bit is used in current
programming model (0: flush, 1: invalidate)
The current code targetting 3 bits leads to additional 8 byte AND
operation which can be elided given that only 1 bit is ever set by
software and/or looked at by hardware
before
------
| 80b63324 <__dma_cache_wback_inv_l1>:
| 80b63324: clri r3
| 80b63328: lr r2,[dc_ctrl]
| 80b6332c: and r2,r2,0xfffff1ff <--- 8 bytes insn
| 80b63334: or r2,r2,576
| 80b63338: sr r2,[dc_ctrl]
| ...
| ...
| 80b63360 <__dma_cache_inv_l1>:
| 80b63360: clri r3
| 80b63364: lr r2,[dc_ctrl]
| 80b63368: and r2,r2,0xfffff1ff <--- 8 bytes insn
| 80b63370: bset_s r2,r2,0x9
| 80b63372: sr r2,[dc_ctrl]
| ...
| ...
| 80b6338c <__dma_cache_wback_l1>:
| 80b6338c: clri r3
| 80b63390: lr r2,[dc_ctrl]
| 80b63394: and r2,r2,0xfffff1ff <--- 8 bytes insn
| 80b6339c: sr r2,[dc_ctrl]
after (AND elided totally in 2 cases, replaced with 2 byte BCLR in 3rd)
-----
| 80b63324 <__dma_cache_wback_inv_l1>:
| 80b63324: clri r3
| 80b63328: lr r2,[dc_ctrl]
| 80b6332c: or r2,r2,576
| 80b63330: sr r2,[dc_ctrl]
| ...
| ...
| 80b63358 <__dma_cache_inv_l1>:
| 80b63358: clri r3
| 80b6335c: lr r2,[dc_ctrl]
| 80b63360: bset_s r2,r2,0x9
| 80b63362: sr r2,[dc_ctrl]
| ...
| ...
| 80b6337c <__dma_cache_wback_l1>:
| 80b6337c: clri r3
| 80b63380: lr r2,[dc_ctrl]
| 80b63384: bclr_s r2,r2,0x9
| 80b63386: sr r2,[dc_ctrl]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
On AXS103 release bitfiles, DMA data corruptions were seen because IOC
setup was not following the recommended way in documentation.
Flipping IOC on when caches are enabled or coherency transactions are in
flight, might cause some of the memory operations to not observe
coherency as expected.
So strictly follow the programming model recommendations as documented
in comment header above arc_ioc_setup()
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
if user disables IOC from debugger at startup (by clearing @ioc_enable),
@ioc_exists is cleared too. This means boot prints don't capture the
fact that IOC was present but disabled which could be misleading.
So invert how we use @ioc_enable and @ioc_exists and make it more
canonical. @ioc_exists represent whether hardware is present or not and
stays same whether enabled or not. @ioc_enable is still user driven,
but will be auto-disabled if IOC hardware is not present, i.e. if
@ioc_exist=0. This is opposite to what we were doing before, but much
clearer.
This means @ioc_enable is now the "exported" toggle in rest of code such
as dma mapping API.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
HS release 3.0 provides for even more flexibility in specifying the
volatile address space for mapping peripherals.
With HS 2.1 @start was made flexible / programmable - with HS 3.0 even
@end can be setup (vs. fixed to 0xFFFF_FFFF before).
So add code to reflect that and while at it remove an unused struct
defintion
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The peripheral address space is architectural address window which is
uncached and typically used to wire up peripherals.
For ARC700 cores (ARCompact ISA based) this was fixed to 1GB region
0xC000_0000 - 0xFFFF_FFFF.
For ARCv2 based HS38 cores the start address is flexible and can be
0xC, 0xD, 0xE, 0xF 000_000 by programming AUX_NON_VOLATILE_LIMIT reg
(typically done in bootloader)
Further in cas of PAE, the physical address can extend beyond 4GB so
need to confine this check, otherwise all pages beyond 4GB will be
treated as uncached
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC700 cores with MMU v2 don't have IC_PTAG AUX register and so we only
define ARC_REG_IC_PTAG for MMU versions >= 3.
But current implementation of cache_line_loop_vX() routines assumes
availability of all of them (v2, v3 and v4) simultaneously.
And given undefined ARC_REG_IC_PTAG if CONFIG_MMU_VER=2 we're seeing
compilation problem:
---------------------------------->8-------------------------------
CC arch/arc/mm/cache.o
arch/arc/mm/cache.c: In function '__cache_line_loop_v3':
arch/arc/mm/cache.c:270:13: error: 'ARC_REG_IC_PTAG' undeclared (first use in this function)
aux_tag = ARC_REG_IC_PTAG;
^
arch/arc/mm/cache.c:270:13: note: each undeclared identifier is reported only once for each function it appears in
scripts/Makefile.build:258: recipe for target 'arch/arc/mm/cache.o' failed
---------------------------------->8-------------------------------
The simples fix is to have ARC_REG_IC_PTAG defined regardless MMU
version being used.
We don't use it in cache_line_loop_v2() anyways so who cares.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This is the first working implementation of 40-bit physical address
extension on ARCv2.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
In case of ARCv2 CPU there're could be following configurations
that affect cache handling for data exchanged with peripherals
via DMA:
[1] Only L1 cache exists
[2] Both L1 and L2 exist, but no IO coherency unit
[3] L1, L2 caches and IO coherency unit exist
Current implementation takes care of [1] and [2].
Moreover support of [2] is implemented with run-time check
for SLC existence which is not super optimal.
This patch introduces support of [3] and rework of DMA ops
usage. Instead of doing run-time check every time a particular
DMA op is executed we'll have 3 different implementations of
DMA ops and select appropriate one during init.
As for IOC support for it we need:
[a] Implement empty DMA ops because IOC takes care of cache
coherency with DMAed data
[b] Route dma_alloc_coherent() via dma_alloc_noncoherent()
This is required to make IOC work in first place and also
serves as optimization as LD/ST to coherent buffers can be
srviced from caches w/o going all the way to memory
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
[vgupta:
-Added some comments about IOC gains
-Marked dma ops as static,
-Massaged changelog a bit]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
L2 cache on ARCHS processors is called SLC (System Level Cache)
For working DMA (in absence of hardware assisted IO Coherency) we need
to manage SLC explicitly when buffers transition between cpu and
controllers.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Caveats about cache flush on ARCv2 based cores
- dcache is PIPT so paddr is sufficient for cache maintenance ops (no
need to setup PTAG reg
- icache is still VIPT but only aliasing configs need PTAG setup
So basically this is departure from MMU-v3 which always need vaddr in
line ops registers (DC_IVDL, DC_FLDL, IC_IVIL) but paddr in DC_PTAG,
IC_PTAG respectively.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
There's no Kconfig symbol ARC_MMU_V4 so the checks for CONFIG_ARC_MMU_V4
will always evaluate to false. Remove them.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
--------------->8--------------------
WARNING: vmlinux.o(.text+0x708): Section mismatch in reference from the
function read_arc_build_cfg_regs() to the function
.init.text:read_decode_cache_bcr()
WARNING: vmlinux.o(.text+0x702): Section mismatch in reference from the
function read_arc_build_cfg_regs() to the function
.init.text:read_decode_mmu_bcr()
--------------->8--------------------
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>
* ARC700 has VIPT L1 Caches
* Caches don't snoop and are not coherent
* Given the PAGE_SIZE and Cache associativity, we don't support aliasing
D$ configurations (yet), but do allow aliasing I$ configs
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* L1_CACHE_SHIFT
* PAGE_SIZE, PAGE_OFFSET
* struct pt_regs, struct user_regs_struct
* struct thread_struct, cpu_relax(), task_pt_regs(), start_thread(), ...
* struct thread_info, THREAD_SIZE, INIT_THREAD_INFO(), TIF_*, ...
* BUG()
* ELF_*
* Elf_*
To disallow user-space visibility into some of the core kernel data-types
such as struct pt_regs, #ifdef __KERNEL__ which also makes the UAPI header
spit (further patch in the series) to NOT export it to asm/uapi/ptrace.h
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Jonas Bonn <jonas.bonn@gmail.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Alexey Brodkin