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* ARC: [tlb-miss] Fix bug with CONFIG_ARC_DBG_TLB_MISS_COUNTVineet Gupta2013-06-271-5/+5
| | | | | | | | | | | | 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>
* ARC: [tlb-miss] Extraneous PTE bit testing/settingVineet Gupta2013-06-271-5/+5
| | | | | | | | | | | | * 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>
* ARC: Remove explicit passing around of ECRVineet Gupta2013-06-261-1/+0
| | | | | | | | | | | | 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>
* ARC: [mm] Remove @write argument to do_page_fault()Vineet Gupta2013-06-221-12/+2
| | | | | | | | | | | | | | | | | | | | | | | | 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>
* ARC: Disintegrate arcregs.hVineet Gupta2013-06-221-1/+1
| | | | | | | | | * 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>
* ARC: copy_(to|from)_user() to honor usermode-access permissionsVineet Gupta2013-05-231-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* ARC: Support for single cycle Close Coupled Mem (CCM)Vineet Gupta2013-02-151-3/+2
| | | | | | | | | * Includes mapping of CCMs in address space * Annotations to move arbitrary code/data into CCM * Moving some of the critical code/data into CCM * Runtime detection/reporting Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* ARC: SMP supportVineet Gupta2013-02-151-0/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ARC common code to enable a SMP system + ISS provided SMP extensions. ARC700 natively lacks SMP support, hence some of the core features are are only enabled if SoCs have the necessary h/w pixie-dust. This includes: -Inter Processor Interrupts (IPI) -Cache coherency -load-locked/store-conditional ... The low level exception handling would be completely broken in SMP because we don't have hardware assisted stack switching. Thus a fair bit of this code is repurposing the MMU_SCRATCH reg for event handler prologues to keep them re-entrant. Many thanks to Rajeshwar Ranga for his initial "major" contributions to SMP Port (back in 2008), and to Noam Camus and Gilad Ben-Yossef for help with resurrecting that in 3.2 kernel (2012). Note that this platform code is again singleton design pattern - so multiple SMP platforms won't build at the moment - this deficiency is addressed in subsequent patches within this series. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Rajeshwar Ranga <rajeshwar.ranga@gmail.com> Cc: Noam Camus <noamc@ezchip.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com>
* ARC: Diagnostics: show_regs() etcVineet Gupta2013-02-151-0/+20
| | | | Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* ARC: MMU Exception HandlingVineet Gupta2013-02-151-0/+351
* MMU I-TLB / D-TLB Miss Exceptions - Fast Path TLB Refill Handler - slowpath TLB creation via do_page_fault() -> update_mmu_cache() * Duplicate PD Exception Handler Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
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