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2012-09-25ARM: mm: update __v7_setup() to the new LoUIS cache maintenance APISantosh Shilimkar
The ARMv7 processor setup function __v7_setup() cleans and invalidates the CPU cache before enabling MMU to start the CPU with a clean CPU local cache. But on ARMv7 architectures like Cortex-[A15/A8], this code will end up flushing the L2 caches(up to level of Coherency) which is undesirable and expensive. The setup functions are used in the CPU hotplug scenario too and hence flushing all cache levels should be avoided. This patch replaces the cache flushing call with the newly introduced v7 dcache LoUIS API where only cache levels up to LoUIS are cleaned and invalidated when a processors executes __v7_setup which is the expected behavior. For processors like A9 and A5 where the L2 cache is an outer one the behavior should be unchanged. Reviewed-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Tested-by: Shawn Guo <shawn.guo@linaro.org>
2012-04-15ARM: 7384/1: ThumbEE: Disable userspace TEEHBR access for !CONFIG_ARM_THUMBEEJonathan Austin
Currently when ThumbEE is not enabled (!CONFIG_ARM_THUMBEE) the ThumbEE register states are not saved/restored at context switch. The default state of the ThumbEE Ctrl register (TEECR) allows userspace accesses to the ThumbEE Base Handler register (TEEHBR). This can cause unexpected behaviour when people use ThumbEE on !CONFIG_ARM_THUMBEE kernels, as well as allowing covert communication - eg between userspace tasks running inside chroot jails. This patch sets up TEECR in order to prevent user-space access to TEEHBR when !CONFIG_ARM_THUMBEE. In this case, tasks are sent SIGILL if they try to access TEEHBR. Cc: stable@vger.kernel.org Reviewed-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Jonathan Austin <jonathan.austin@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-02-27ARM: 7345/1: errata: update workaround for A9 erratum #743622Will Deacon
Erratum #743622 affects all r2 variants of the Cortex-A9 processor, so ensure that the workaround is applied regardless of the revision. Cc: <stable@vger.kernel.org> Reported-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-01-23ARM: 7296/1: proc-v7.S: remove HARVARD_CACHE preprocessor guardsWill Deacon
On v7, we use the same cache maintenance instructions for data lines as for unified lines. This was not the case for v6, where HARVARD_CACHE was defined to indicate the L1 cache topology. This patch removes the erroneous compile-time check for HARVARD_CACHE in proc-v7.S, ensuring that we perform I-side invalidation at boot. Reported-and-Acked-by: Shawn Guo <shawn.guo@linaro.org> Cc: stable <stable@vger.kernel.org> Acked-by: Catalin Marinas <Catalin.Marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-01-23ARM: 7295/1: cortex-a7: move proc_info out of !CONFIG_ARM_LPAE blockWill Deacon
The merging of commits 1b6ba46b ("ARM: LPAE: MMU setup for the 3-level page table format") and b4244738 ("ARM: 7202/1: Add Cortex-A7 proc info") during the merge window ended up putting the Cortex-A7 proc_info into a code block guarded by !CONFIG_ARM_LPAE. This makes Cortex-A7 platforms unbootable when LPAE is enabled. This patch moves the proc_info structure for Cortex-A7 outside of the guarded block. Cc: Pawel Moll <pawel.moll@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-01-05Merge branch 'devel-stable' into for-linusRussell King
Conflicts: arch/arm/kernel/setup.c arch/arm/mach-shmobile/board-kota2.c
2012-01-05Merge branches 'fixes' and 'misc' into for-linusRussell King
2011-12-23ARM: 7197/1: errata: Remove SMP dependency for erratum 751472Dave Martin
Activation conditions for a workaround should not be encoded in the workaround's direct dependencies if this makes otherwise reasonable configuration choices impossible. This patches uses the SMP/UP patching facilities instead to compile out the workaround if the configuration means that it is definitely not needed. This means that configs for buggy silicon can simply select ARM_ERRATA_751472, without preventing a UP kernel from being built or duplicatiing knowledge about when to activate the workaround. This seems the correct way to do things, because the erratum is a property of the silicon, irrespective of what the kernel config happens to be. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-12-11ARM: 7202/1: Add Cortex-A7 proc infoPawel Moll
This patch adds processor info for ARM Ltd. Cortex-A7. A7 is architecturally identical to A15 so it shares the same SMP initialization code and hwcaps. Tested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-12-08ARM: LPAE: MMU setup for the 3-level page table formatCatalin Marinas
This patch adds the MMU initialisation for the LPAE page table format. The swapper_pg_dir size with LPAE is 5 rather than 4 pages. A new proc-v7-3level.S file contains the TTB initialisation, context switch and PTE setting code with the LPAE. The TTBRx split is based on the PAGE_OFFSET with TTBR1 used for the kernel mappings. The 36-bit mappings (supersections) and a few other memory types in mmu.c are conditionally compiled. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2011-12-08ARM: LPAE: Factor out classic-MMU specific code into proc-v7-2level.SCatalin Marinas
This patch modifies the proc-v7.S file so that it only contains code shared between classic MMU and LPAE. The non-common code is factored out into a separate file. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2011-12-06ARM: proc-*.S: place cpu_reset functions into .idmap.text sectionWill Deacon
The CPU reset functions disable the MMU and therefore must be executed with an identity mapping in place. This patch places the CPU reset functions into the .idmap.text section, causing the idmap code to include them as part of the identity mapping. Acked-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-10-28Merge branch 'devel-stable' of ↵Linus Torvalds
http://ftp.arm.linux.org.uk/pub/linux/arm/kernel/git-cur/linux-2.6-arm * 'devel-stable' of http://ftp.arm.linux.org.uk/pub/linux/arm/kernel/git-cur/linux-2.6-arm: (178 commits) ARM: 7139/1: fix compilation with CONFIG_ARM_ATAG_DTB_COMPAT and large TEXT_OFFSET ARM: gic, local timers: use the request_percpu_irq() interface ARM: gic: consolidate PPI handling ARM: switch from NO_MACH_MEMORY_H to NEED_MACH_MEMORY_H ARM: mach-s5p64x0: remove mach/memory.h ARM: mach-s3c64xx: remove mach/memory.h ARM: plat-mxc: remove mach/memory.h ARM: mach-prima2: remove mach/memory.h ARM: mach-zynq: remove mach/memory.h ARM: mach-bcmring: remove mach/memory.h ARM: mach-davinci: remove mach/memory.h ARM: mach-pxa: remove mach/memory.h ARM: mach-ixp4xx: remove mach/memory.h ARM: mach-h720x: remove mach/memory.h ARM: mach-vt8500: remove mach/memory.h ARM: mach-s5pc100: remove mach/memory.h ARM: mach-tegra: remove mach/memory.h ARM: plat-tcc: remove mach/memory.h ARM: mach-mmp: remove mach/memory.h ARM: mach-cns3xxx: remove mach/memory.h ... Fix up mostly pretty trivial conflicts in: - arch/arm/Kconfig - arch/arm/include/asm/localtimer.h - arch/arm/kernel/Makefile - arch/arm/mach-shmobile/board-ap4evb.c - arch/arm/mach-u300/core.c - arch/arm/mm/dma-mapping.c - arch/arm/mm/proc-v7.S - arch/arm/plat-omap/Kconfig largely due to some CONFIG option renaming (ie CONFIG_PM_SLEEP -> CONFIG_ARM_CPU_SUSPEND for the arm-specific suspend code etc) and addition of NEED_MACH_MEMORY_H next to HAVE_IDE.
2011-10-25Merge branches 'arnd-randcfg-fixes', 'debug', 'io' (early part), 'l2x0', ↵Russell King
'p2v', 'pgt' (early part) and 'smp' into for-linus
2011-10-01ARM: pm: let platforms select cpu_suspend supportArnd Bergmann
Support for the cpu_suspend functions is only built-in when CONFIG_PM_SLEEP is enabled, but omap3/4, exynos4 and pxa always call cpu_suspend when CONFIG_PM is enabled. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2011-09-20ARM: pm: no need to save/restore context ID registerRussell King
There is no need to save and restore the context ID register on ARMv6 and ARMv7 with a temporary page table as we write the context ID register when we switch back to the real page tables for the thread. Moreover, the temporary page tables do not contain any non-global mappings, so the context ID value should not be used. To be safe, initialize the register to a reserved context ID value. Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-09-20ARM: pm: only use preallocated page table during resumeRussell King
Only use the preallocated page table during the resume, not while suspending. This avoids the overhead of having to switch unnecessarily to the resume page table in the suspend path. Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-09-20ARM: pm: preallocate a page table for suspend/resumeRussell King
Preallocate a page table and setup an identity mapping for the MMU enable code. This means we don't have to "borrow" a page table to do this, avoiding complexities with L2 cache coherency. Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-08-28ARM: pm: avoid writing the auxillary control register for ARMv7Russell King
For ARMv7 kernels running in the non-secure world, writing to the auxillary control register causes an abort, so we must avoid directly writing the auxillary control register. If the ACR has already been reinitialized by SoC code, don't try to restore it. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-08-28ARM: pm: some ARMv7 requires a dsb in resume to ensure correctnessRussell King
Add a dsb after the isb to ensure that the previous writes to the CP15 registers take effect before we enable the MMU. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-08-28ARM: 7066/1: proc-v7: disable SCTLR.TE when disabling MMUWill Deacon
cpu_v7_reset disables the MMU and then branches to the provided address. On Thumb-2 kernels, we should take care to clear the Thumb Exception enable bit in the System Control Register, otherwise this may wreak havok in the code to which we are branching (for example, an ARM kernel image via kexec). Reviewed-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-21ARM: Fix build errors caused by adding generic macrosRussell King
Commit 66a625a (ARM: mm: proc-macros: Add generic proc/cache/tlb struct definition macros) introduced build errors when PM_SLEEP is not enabled. The per-CPU do_suspend/do_resume functions are defined via the preprocessor to constant 0. However, the macros which use these were converted to assembly, resulting in undefined references to these functions. Fix that by moving the ! ifdef section into proc-macros.S and deleting it from all effected proc-*.S files. Acked-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-07ARM: proc: add definition of cpu_reset for ARMv6 and ARMv7 coresWill Deacon
This patch adds simple definitions of cpu_reset for ARMv6 and ARMv7 cores, which disable the MMU via the SCTLR. Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: proc: add proc info for Cortex-A15MP using classic page tablesWill Deacon
Multicore implementations of the Cortex-A15 require bit 6 of the auxiliary control register to be set in order for cache and TLB maintenance operations to be broadcast between CPUs. This patch adds a new proc_info structure for Cortex-A15, which enables the SMP bit during setup and includes the new HWCAP for integer division. Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: proc: add Cortex-A5 proc infoPawel Moll
This patch adds processor info for ARM Ltd. Cortex A5, which has SCU initialisation procedure identical to A9. Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: proc: convert v7 proc infos into a common macroPawel Moll
As most of the proc info content is common across all v7 processors, this patch converts existing A9 and generic v7 descriptions into a macro (allowing extra flags in future). Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: mm: proc-v7: Use the new processor struct macrosDave Martin
Signed-off-by: Dave Martin <dave.martin@linaro.org>
2011-06-24ARM: pm: ensure ARMv7 CPUs save and restore the TLS registerRussell King
Ensure that the TLS register is saved and restored over a suspend cycle, so that userspace programs don't see a corrupted TLS value. Tested-by: Kevin Hilman <khilman@ti.com> Acked-by: Jean Pihet <j-pihet@ti.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-06-24ARM: pm: proc-v7: fix missing struct processor pointers for suspend codeRussell King
Add the missing suspend/resume pointers for the suspend code. This is needed when building for multiple CPUs. Tested-by: Kevin Hilman <khilman@ti.com> Acked-by: Jean Pihet <j-pihet@ti.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-06-09Revert "ARM: 6943/1: mm: use TTBR1 instead of reserved context ID"Russell King
This reverts commit 52af9c6cd863fe37d1103035ec7ee22ac1296458. Will Deacon reports that: In 52af9c6c ("ARM: 6943/1: mm: use TTBR1 instead of reserved context ID") I updated the ASID rollover code to use only the kernel page tables whilst updating the ASID. Unfortunately, the code to restore the user page tables was part of a later patch which isn't yet in mainline, so this leaves the code quite broken. We're also in the process of eliminating __ARCH_WANT_INTERRUPTS_ON_CTXSW from ARM, so lets revert these until we can properly sort out what we're doing with the ARM context switching. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-05-26ARM: 6943/1: mm: use TTBR1 instead of reserved context IDWill Deacon
On ARMv7 CPUs that cache first level page table entries (like the Cortex-A15), using a reserved ASID while changing the TTBR or flushing the TLB is unsafe. This is because the CPU may cache the first level entry as the result of a speculative memory access while the reserved ASID is assigned. After the process owning the page tables dies, the memory will be reallocated and may be written with junk values which can be interpreted as global, valid PTEs by the processor. This will result in the TLB being populated with bogus global entries. This patch avoids the use of a reserved context ID in the v7 switch_mm and ASID rollover code by temporarily using the swapper_pg_dir pointed at by TTBR1, which contains only global entries that are not tagged with ASIDs. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-05-26ARM: 6942/1: mm: make TTBR1 always point to swapper_pg_dir on ARMv6/7Catalin Marinas
This patch makes TTBR1 point to swapper_pg_dir so that global, kernel mappings can be used exclusively on v6 and v7 cores where they are needed. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-04-13Merge branch 'fix' of ↵Russell King
git://git.kernel.org/pub/scm/linux/kernel/git/ycmiao/pxa-linux-2.6 into fixes
2011-04-02ARM: Make consolidated PM sleep code depend on PM_SLEEPRussell King
CONFIG_PM is now set whenever we support either runtime PM in addition to suspend and hibernate. This causes build errors when runtime PM is enabled on a platform, but the CPU does not have the appropriate support for suspend. So, switch this code to use CONFIG_PM_SLEEP rather than CONFIG_PM to allow runtime PM to be enabled without causing build errors. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-03-31Fix common misspellingsLucas De Marchi
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-16Merge branches 'at91', 'ep93xx', 'errata', 'footbridge', 'fncpy', 'gemini', ↵Russell King
'irqdata', 'pm', 'sh', 'smp', 'spear', 'ux500' and 'via' into devel
2011-03-09ARM: 6772/1: errata: possible fault MMU translations following an ASID switchWill Deacon
On the r2p* and r3p* versions of the Cortex-A9, a speculative memory access may cause a page table walk which starts prior to an ASID switch but completes afterwards. This can populate the micro-TLB with a stale entry which may be hit with the new ASID. This workaround places two dsb instructions in the mm switching code so that no page table walks can cross the ASID switch. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-22ARM: pm: add generic CPU suspend/resume supportRussell King
This adds core support for saving and restoring CPU coprocessor registers for suspend/resume support. This contains support for suspend with ARM920, ARM926, SA11x0, PXA25x, PXA27x, PXA3xx, V6 and V7 CPUs. Tested on Assabet and Tegra 2. Tested-by: Colin Cross <ccross@android.com> Tested-by: Kukjin Kim <kgene.kim@samsung.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-19ARM: 6743/1: errata: interrupted ICALLUIS may prevent completion of ↵Will Deacon
broadcasted operation On versions of the Cortex-A9 prior to r3p0, an interrupted ICIALLUIS operation may prevent the completion of a following broadcasted operation if the second operation is received by a CPU before the ICIALLUIS has completed, potentially leading to corrupted entries in the cache or TLB. This workaround sets a bit in the diagnostic register of the Cortex-A9, causing CP15 maintenance operations to be uninterruptible. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-01-14ARM: 6623/1: Thumb-2: Fix out-of-range offset for Thumb-2 in proc-v7.SDave Martin
Commit d30e45e (ARM: pgtable: switch order of Linux vs hardware page tables) introduced a pre-increment addressing offset which is out of range for Thumb-2. Thumb-2 only permits offsets <256. So split the intruction in two for Thumb-2. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-01-06Merge branch 'pgt' (early part) into develRussell King
2011-01-06Merge branch 'misc' into develRussell King
Conflicts: arch/arm/Kconfig arch/arm/common/Makefile arch/arm/kernel/Makefile arch/arm/kernel/smp.c
2010-12-22ARM: pgtable: provide RDONLY page table bit rather than WRITE bitRussell King
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-12-22ARM: pgtable: invert L_PTE_EXEC to L_PTE_XNRussell King
The hardware page tables use an XN bit 'execute never'. Historically, we've had a Linux 'execute allow' bit, in the positive sense. Get rid of this artifact as future hardware will continue to have the XN sense. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-12-22ARM: pgtable: switch order of Linux vs hardware page tablesRussell King
This switches the ordering of the Linux vs hardware page tables in each page, thereby eliminating some of the arithmetic in the page table walks. As we now place the Linux page table at the beginning of the page, we can deal with the offset in the pgt by simply masking it away, along with the other control bits. This also makes the arithmetic all be positive, rather than a mixture. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-11-30ARM: 6501/1: Thumb-2: Correct data alignment for CONFIG_THUMB2_KERNEL in ↵Dave Martin
mm/proc-v7.S Directives such as .long and .word do not magically cause the assembler location counter to become aligned in gas. As a result, using these directives in code sections can result in misaligned data words when building a Thumb-2 kernel (CONFIG_THUMB2_KERNEL). This is a Bad Thing, since the ABI permits the compiler to assume that fundamental types of word size or above are word- aligned when accessing them from C. If the data is not really word-aligned, this can cause impaired performance and stray alignment faults in some circumstances. In general, the following rules should be applied when using data word declaration directives inside code sections: * .quad and .double: .align 3 * .long, .word, .single, .float: .align (or .align 2) * .short: No explicit alignment required, since Thumb-2 instructions are always 2 or 4 bytes in size. immediately after an instruction. In this specific case, we can achieve the desired alignment by forcing a 32-bit branch instruction using the W() macro, since the assembler location counter is already 32-bit aligned in this case. Reviewed-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Dave Martin <dave.martin@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-11-04ARM: 6396/1: Add SWP/SWPB emulation for ARMv7 processorsLeif Lindholm
The SWP instruction was deprecated in the ARMv6 architecture, superseded by the LDREX/STREX family of instructions for load-linked/store-conditional operations. The ARMv7 multiprocessing extensions mandate that SWP/SWPB instructions are treated as undefined from reset, with the ability to enable them through the System Control Register SW bit. This patch adds the alternative solution to emulate the SWP and SWPB instructions using LDREX/STREX sequences, and log statistics to /proc/cpu/swp_emulation. To correctly deal with copy-on-write, it also modifies cpu_v7_set_pte_ext to change the mappings to priviliged RO when user RO. Signed-off-by: Leif Lindholm <leif.lindholm@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-11-04ARM: 6384/1: Remove the domain switching on ARMv6k/v7 CPUsCatalin Marinas
This patch removes the domain switching functionality via the set_fs and __switch_to functions on cores that have a TLS register. Currently, the ioremap and vmalloc areas share the same level 1 page tables and therefore have the same domain (DOMAIN_KERNEL). When the kernel domain is modified from Client to Manager (via the __set_fs or in the __switch_to function), the XN (eXecute Never) bit is overridden and newer CPUs can speculatively prefetch the ioremap'ed memory. Linux performs the kernel domain switching to allow user-specific functions (copy_to/from_user, get/put_user etc.) to access kernel memory. In order for these functions to work with the kernel domain set to Client, the patch modifies the LDRT/STRT and related instructions to the LDR/STR ones. The user pages access rights are also modified for kernel read-only access rather than read/write so that the copy-on-write mechanism still works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register (CPU_32v6K is defined) since writing the TLS value to the high vectors page isn't possible. The user addresses passed to the kernel are checked by the access_ok() function so that they do not point to the kernel space. Tested-by: Anton Vorontsov <cbouatmailru@gmail.com> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-10-19Merge branch 'devel-stable' into develRussell King
2010-10-18Merge branch 'hotplug' into develRussell King
Conflicts: arch/arm/kernel/head-common.S