- 29 9月, 2017 1 次提交
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由 Will Deacon 提交于
We currently route pte translation faults via do_page_fault, which elides the address check against TASK_SIZE before invoking the mm fault handling code. However, this can cause issues with the path walking code in conjunction with our word-at-a-time implementation because load_unaligned_zeropad can end up faulting in kernel space if it reads across a page boundary and runs into a page fault (e.g. by attempting to read from a guard region). In the case of such a fault, load_unaligned_zeropad has registered a fixup to shift the valid data and pad with zeroes, however the abort is reported as a level 3 translation fault and we dispatch it straight to do_page_fault, despite it being a kernel address. This results in calling a sleeping function from atomic context: BUG: sleeping function called from invalid context at arch/arm64/mm/fault.c:313 in_atomic(): 0, irqs_disabled(): 0, pid: 10290 Internal error: Oops - BUG: 0 [#1] PREEMPT SMP [...] [<ffffff8e016cd0cc>] ___might_sleep+0x134/0x144 [<ffffff8e016cd158>] __might_sleep+0x7c/0x8c [<ffffff8e016977f0>] do_page_fault+0x140/0x330 [<ffffff8e01681328>] do_mem_abort+0x54/0xb0 Exception stack(0xfffffffb20247a70 to 0xfffffffb20247ba0) [...] [<ffffff8e016844fc>] el1_da+0x18/0x78 [<ffffff8e017f399c>] path_parentat+0x44/0x88 [<ffffff8e017f4c9c>] filename_parentat+0x5c/0xd8 [<ffffff8e017f5044>] filename_create+0x4c/0x128 [<ffffff8e017f59e4>] SyS_mkdirat+0x50/0xc8 [<ffffff8e01684e30>] el0_svc_naked+0x24/0x28 Code: 36380080 d5384100 f9400800 9402566d (d4210000) ---[ end trace 2d01889f2bca9b9f ]--- Fix this by dispatching all translation faults to do_translation_faults, which avoids invoking the page fault logic for faults on kernel addresses. Cc: <stable@vger.kernel.org> Reported-by: NAnkit Jain <ankijain@codeaurora.org> Signed-off-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 23 8月, 2017 1 次提交
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由 Mark Rutland 提交于
When there's a fatal signal pending, arm64's do_page_fault() implementation returns 0. The intent is that we'll return to the faulting userspace instruction, delivering the signal on the way. However, if we take a fatal signal during fixing up a uaccess, this results in a return to the faulting kernel instruction, which will be instantly retried, resulting in the same fault being taken forever. As the task never reaches userspace, the signal is not delivered, and the task is left unkillable. While the task is stuck in this state, it can inhibit the forward progress of the system. To avoid this, we must ensure that when a fatal signal is pending, we apply any necessary fixup for a faulting kernel instruction. Thus we will return to an error path, and it is up to that code to make forward progress towards delivering the fatal signal. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Laura Abbott <labbott@redhat.com> Cc: stable@vger.kernel.org Reviewed-by: NSteve Capper <steve.capper@arm.com> Tested-by: NSteve Capper <steve.capper@arm.com> Reviewed-by: NJames Morse <james.morse@arm.com> Tested-by: NJames Morse <james.morse@arm.com> Signed-off-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 21 8月, 2017 3 次提交
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由 Catalin Marinas 提交于
Since the pte handling for hardware AF/DBM works even when the hardware feature is not present, make the pte accessors implementation permanent and remove the corresponding #ifdefs. The Kconfig option is kept as it can still be used to disable the feature at the hardware level. Reviewed-by: NWill Deacon <will.deacon@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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由 Catalin Marinas 提交于
Currently PTE_RDONLY is treated as a hardware only bit and not handled by the pte_mkwrite(), pte_wrprotect() or the user PAGE_* definitions. The set_pte_at() function is responsible for setting this bit based on the write permission or dirty state. This patch moves the PTE_RDONLY handling out of set_pte_at into the pte_mkwrite()/pte_wrprotect() functions. The PAGE_* definitions to need to be updated to explicitly include PTE_RDONLY when !PTE_WRITE. The patch also removes the redundant PAGE_COPY(_EXEC) definitions as they are identical to the corresponding PAGE_READONLY(_EXEC). Reviewed-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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由 Catalin Marinas 提交于
With the support for hardware updates of the access and dirty states, the following pte handling functions had to be implemented using exclusives: __ptep_test_and_clear_young(), ptep_get_and_clear(), ptep_set_wrprotect() and ptep_set_access_flags(). To take advantage of the LSE atomic instructions and also make the code cleaner, convert these pte functions to use the more generic cmpxchg()/xchg(). Reviewed-by: NWill Deacon <will.deacon@arm.com> Acked-by: NMark Rutland <mark.rutland@arm.com> Acked-by: NSteve Capper <steve.capper@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 07 8月, 2017 1 次提交
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由 Julien Thierry 提交于
When receiving unhandled faults from the CPU, description is very sparse. Adding information about faults decoded from ESR. Added defines to esr.h corresponding ESR fields. Values are based on ARM Archtecture Reference Manual (DDI 0487B.a), section D7.2.28 ESR_ELx, Exception Syndrome Register (ELx) (pages D7-2275 to D7-2280). New output is of the form: [ 77.818059] Mem abort info: [ 77.820826] Exception class = DABT (current EL), IL = 32 bits [ 77.826706] SET = 0, FnV = 0 [ 77.829742] EA = 0, S1PTW = 0 [ 77.832849] Data abort info: [ 77.835713] ISV = 0, ISS = 0x00000070 [ 77.839522] CM = 0, WnR = 1 Signed-off-by: NJulien Thierry <julien.thierry@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> [catalin.marinas@arm.com: fix "%lu" in a pr_alert() call] Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 04 8月, 2017 1 次提交
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由 Catalin Marinas 提交于
In a system with DBM (dirty bit management) capable agents there is a possible race between a CPU executing ptep_set_access_flags() (maybe non-DBM capable) and a hardware update of the dirty state (clearing of PTE_RDONLY). The scenario: a) the pte is writable (PTE_WRITE set), clean (PTE_RDONLY set) and old (PTE_AF clear) b) ptep_set_access_flags() is called as a result of a read access and it needs to set the pte to writable, clean and young (PTE_AF set) c) a DBM-capable agent, as a result of a different write access, is marking the entry as young (setting PTE_AF) and dirty (clearing PTE_RDONLY) The current ptep_set_access_flags() implementation would set the PTE_RDONLY bit in the resulting value overriding the DBM update and losing the dirty state. This patch fixes such race by setting PTE_RDONLY to the most permissive (lowest value) of the current entry and the new one. Fixes: 66dbd6e6 ("arm64: Implement ptep_set_access_flags() for hardware AF/DBM") Cc: Will Deacon <will.deacon@arm.com> Acked-by: NMark Rutland <mark.rutland@arm.com> Acked-by: NSteve Capper <steve.capper@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 23 6月, 2017 3 次提交
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由 Tyler Baicar 提交于
Currently external aborts are unsupported by the guest abort handling. Add handling for SEAs so that the host kernel reports SEAs which occur in the guest kernel. When an SEA occurs in the guest kernel, the guest exits and is routed to kvm_handle_guest_abort(). Prior to this patch, a print message of an unsupported FSC would be printed and nothing else would happen. With this patch, the code gets routed to the APEI handling of SEAs in the host kernel to report the SEA information. Signed-off-by: NTyler Baicar <tbaicar@codeaurora.org> Acked-by: NCatalin Marinas <catalin.marinas@arm.com> Acked-by: NMarc Zyngier <marc.zyngier@arm.com> Acked-by: NChristoffer Dall <cdall@linaro.org> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Tyler Baicar 提交于
ARM APEI extension proposal added SEA (Synchronous External Abort) notification type for ARMv8. Add a new GHES error source handling function for SEA. If an error source's notification type is SEA, then this function can be registered into the SEA exception handler. That way GHES will parse and report SEA exceptions when they occur. An SEA can interrupt code that had interrupts masked and is treated as an NMI. To aid this the page of address space for mapping APEI buffers while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is changed to use the helper methods to find the prot_t to map with in the same way as ghes_ioremap_pfn_irq(). Signed-off-by: NTyler Baicar <tbaicar@codeaurora.org> CC: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org> Reviewed-by: NJames Morse <james.morse@arm.com> Acked-by: NCatalin Marinas <catalin.marinas@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Tyler Baicar 提交于
SEA exceptions are often caused by an uncorrected hardware error, and are handled when data abort and instruction abort exception classes have specific values for their Fault Status Code. When SEA occurs, before killing the process, report the error in the kernel logs. Update fault_info[] with specific SEA faults so that the new SEA handler is used. Signed-off-by: NTyler Baicar <tbaicar@codeaurora.org> CC: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org> Reviewed-by: NJames Morse <james.morse@arm.com> Acked-by: NCatalin Marinas <catalin.marinas@arm.com> [will: use NULL instead of 0 when assigning si_addr] Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 12 6月, 2017 6 次提交
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由 Punit Agrawal 提交于
Re-organise the perf accounting for fault handling in preparation for enabling handling of hardware poison faults in subsequent commits. The change updates perf accounting to be inline with the behaviour on x86. With this update, the perf fault accounting - * Always report PERF_COUNT_SW_PAGE_FAULTS * Doesn't report anything else for VM_FAULT_ERROR (which includes hwpoison faults) * Reports PERF_COUNT_SW_PAGE_FAULTS_MAJ if it's a major fault (indicated by VM_FAULT_MAJOR) * Otherwise, reports PERF_COUNT_SW_PAGE_FAULTS_MIN Signed-off-by: NPunit Agrawal <punit.agrawal@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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Add VM_FAULT_HWPOISON[_LARGE] handling to the arm64 page fault handler. Handling of VM_FAULT_HWPOISON[_LARGE] is very similar to VM_FAULT_OOM, the only difference is that a different si_code (BUS_MCEERR_AR) is passed to user space and si_addr_lsb field is initialized. Signed-off-by: NJonathan (Zhixiong) Zhang <zjzhang@codeaurora.org> Signed-off-by: NTyler Baicar <tbaicar@codeaurora.org> (fix new __do_user_fault call-site) Signed-off-by: NPunit Agrawal <punit.agrawal@arm.com> Acked-by: NSteve Capper <steve.capper@arm.com> Tested-by: NManoj Iyer <manoj.iyer@canonical.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
Whilst debugging a remote crash, I noticed that show_pte is unhelpful when it comes to describing the structure of the page table being walked. This is easily fixed by printing out the page table (swapper vs user), page size and virtual address size when displaying the PGD address. Acked-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Kristina Martsenko 提交于
Print out the name of the file associated with the vma that faulted. This is usually the executable or shared library name. We already print out the task name, but also printing the library name is useful for pinpointing bugs to libraries. Also print the base address and size of the vma, which together with the PC (printed by __show_regs) gives the offset into the library. Fault prints now look like: test[2361]: unhandled level 2 translation fault (11) at 0x00000012, esr 0x92000006, in libfoo.so[ffffa0145000+1000] This is already done on x86, for more details see commit 03252919 ("x86: print which shared library/executable faulted in segfault etc. messages v3"). Acked-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Kristina Martsenko 提交于
When we take a fault from EL0 that can't be handled, we print out the page table entries associated with the faulting address. This allows userspace to print out any current page table entries, including kernel (TTBR1) entries. Exposing kernel mappings like this could pose a security risk, so don't print out page table information on EL0 faults. (But still print it out for EL1 faults.) This also follows the same behaviour as x86, printing out page table entries on kernel mode faults but not user mode faults. Acked-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Kristina Martsenko 提交于
When we take a fault that can't be handled, we print out the page table entries associated with the faulting address. In some cases we currently print out the wrong entries. For a faulting TTBR1 address, we sometimes print out TTBR0 table entries instead, and for a faulting TTBR0 address we sometimes print out TTBR1 table entries. Fix this by choosing the tables based on the faulting address. Acked-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com> [will: zero-extend addrs to 64-bit, don't walk swapper w/ TTBR0 addr] Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 30 5月, 2017 1 次提交
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由 Kefeng Wang 提交于
Generic code expects show_regs() to also dump the stack, but arm64's show_reg() does not do this. Some arm64 callers of show_regs() *only* want the registers dumped, without the stack. To enable generic code to work as expected, we need to make show_regs() dump the stack. Where we only want the registers dumped, we must use __show_regs(). This patch updates code to use __show_regs() where only registers are desired. A subsequent patch will modify show_regs(). Acked-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NKefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 07 4月, 2017 1 次提交
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由 Stephen Boyd 提交于
If a page is marked read only we should print out that fact, instead of printing out that there was a page fault. Right now we get a cryptic error message that something went wrong with an unhandled fault, but we don't evaluate the esr to figure out that it was a read/write permission fault. Instead of seeing: Unable to handle kernel paging request at virtual address ffff000008e460d8 pgd = ffff800003504000 [ffff000008e460d8] *pgd=0000000083473003, *pud=0000000083503003, *pmd=0000000000000000 Internal error: Oops: 9600004f [#1] PREEMPT SMP we'll see: Unable to handle kernel write to read-only memory at virtual address ffff000008e760d8 pgd = ffff80003d3de000 [ffff000008e760d8] *pgd=0000000083472003, *pud=0000000083435003, *pmd=0000000000000000 Internal error: Oops: 9600004f [#1] PREEMPT SMP We also add a userspace address check into is_permission_fault() so that the function doesn't return true for ttbr0 PAN faults when it shouldn't. Reviewed-by: NJames Morse <james.morse@arm.com> Tested-by: NJames Morse <james.morse@arm.com> Acked-by: NLaura Abbott <labbott@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: NStephen Boyd <stephen.boyd@linaro.org> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 04 4月, 2017 1 次提交
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由 Victor Kamensky 提交于
After 52d7523d (arm64: mm: allow the kernel to handle alignment faults on user accesses) commit user-land accesses that produce unaligned exceptions like in case of aarch32 ldm/stm/ldrd/strd instructions operating on unaligned memory received by user-land as SIGSEGV. It is wrong, it should be reported as SIGBUS as it was before 52d7523d commit. Changed do_bad_area function to take signal and code parameters out of esr value using fault_info table, so in case of do_alignment_fault fault user-land will receive SIGBUS. Wrapped access to fault_info table into esr_to_fault_info function. Cc: <stable@vger.kernel.org> Fixes: 52d7523d (arm64: mm: allow the kernel to handle alignment faults on user accesses) Signed-off-by: NVictor Kamensky <kamensky@cisco.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 02 3月, 2017 2 次提交
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由 Ingo Molnar 提交于
We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/debug.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Ingo Molnar 提交于
We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/signal.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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- 10 1月, 2017 1 次提交
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由 James Morse 提交于
Since its introduction, the UAO enable call was broken, and useless. commit 2a6dcb2b ("arm64: cpufeature: Schedule enable() calls instead of calling them via IPI"), fixed the framework so that these calls are scheduled, so that they can modify PSTATE. Now it is just useless. Remove it. UAO is enabled by the code patching which causes get_user() and friends to use the 'ldtr' family of instructions. This relies on the PSTATE.UAO bit being set to match addr_limit, which we do in uao_thread_switch() called via __switch_to(). All that is needed to enable UAO is patch the code, and call schedule(). __apply_alternatives_multi_stop() calls stop_machine() when it modifies the kernel text to enable the alternatives, (including the UAO code in uao_thread_switch()). Once stop_machine() has finished __switch_to() is called to reschedule the original task, this causes PSTATE.UAO to be set appropriately. An explicit enable() call is not needed. Reported-by: NVladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: NJames Morse <james.morse@arm.com>
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- 05 1月, 2017 1 次提交
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由 Mark Rutland 提交于
Recent changes made KERN_CONT mandatory for continued lines. In the absence of KERN_CONT, a newline may be implicit inserted by the core printk code. In show_pte, we (erroneously) use printk without KERN_CONT for continued prints, resulting in output being split across a number of lines, and not matching the intended output, e.g. [ff000000000000] *pgd=00000009f511b003 , *pud=00000009f4a80003 , *pmd=0000000000000000 Fix this by using pr_cont() for all the continuations. Acked-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 22 11月, 2016 2 次提交
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由 Catalin Marinas 提交于
When TTBR0_EL1 is set to the reserved page, an erroneous kernel access to user space would generate a translation fault. This patch adds the checks for the software-set PSR_PAN_BIT to emulate a permission fault and report it accordingly. Cc: Will Deacon <will.deacon@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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由 Catalin Marinas 提交于
This patch updates the description of the synchronous external aborts on translation table walks. Cc: Will Deacon <will.deacon@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Kees Cook <keescook@chromium.org> Reviewed-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 20 10月, 2016 2 次提交
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由 James Morse 提交于
Commit 338d4f49 ("arm64: kernel: Add support for Privileged Access Never") enabled PAN by enabling the 'SPAN' feature-bit in SCTLR_EL1. This means the PSTATE.PAN bit won't be set until the next return to the kernel from userspace. On a preemptible kernel we may schedule work that accesses userspace on a CPU before it has done this. Now that cpufeature enable() calls are scheduled via stop_machine(), we can set PSTATE.PAN from the cpu_enable_pan() call. Add WARN_ON_ONCE(in_interrupt()) to check the PSTATE value we updated is not immediately discarded. Reported-by: NTony Thompson <anthony.thompson@arm.com> Reported-by: NVladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: NJames Morse <james.morse@arm.com> [will: fixed typo in comment] Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 James Morse 提交于
The enable() call for a cpufeature/errata is called using on_each_cpu(). This issues a cross-call IPI to get the work done. Implicitly, this stashes the running PSTATE in SPSR when the CPU receives the IPI, and restores it when we return. This means an enable() call can never modify PSTATE. To allow PAN to do this, change the on_each_cpu() call to use stop_machine(). This schedules the work on each CPU which allows us to modify PSTATE. This involves changing the protype of all the enable() functions. enable_cpu_capabilities() is called during boot and enables the feature on all online CPUs. This path now uses stop_machine(). CPU features for hotplug'd CPUs are enabled by verify_local_cpu_features() which only acts on the local CPU, and can already modify the running PSTATE as it is called from secondary_start_kernel(). Reported-by: NTony Thompson <anthony.thompson@arm.com> Reported-by: NVladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: NJames Morse <james.morse@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 20 9月, 2016 1 次提交
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由 Paul Gortmaker 提交于
These files were only including module.h for exception table related functions. We've now separated that content out into its own file "extable.h" so now move over to that and avoid all the extra header content in module.h that we don't really need to compile these files. Cc: Catalin Marinas <catalin.marinas@arm.com> Acked-by: NCatalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 26 8月, 2016 1 次提交
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由 Catalin Marinas 提交于
The ARMv8 architecture allows execute-only user permissions by clearing the PTE_UXN and PTE_USER bits. However, the kernel running on a CPU implementation without User Access Override (ARMv8.2 onwards) can still access such page, so execute-only page permission does not protect against read(2)/write(2) etc. accesses. Systems requiring such protection must enable features like SECCOMP. This patch changes the arm64 __P100 and __S100 protection_map[] macros to the new __PAGE_EXECONLY attributes. A side effect is that pte_user() no longer triggers for __PAGE_EXECONLY since PTE_USER isn't set. To work around this, the check is done on the PTE_NG bit via the pte_ng() macro. VM_READ is also checked now for page faults. Reviewed-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 13 8月, 2016 1 次提交
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由 Laura Abbott 提交于
Executing from a non-executable area gives an ugly message: lkdtm: Performing direct entry EXEC_RODATA lkdtm: attempting ok execution at ffff0000084c0e08 lkdtm: attempting bad execution at ffff000008880700 Bad mode in Synchronous Abort handler detected on CPU2, code 0x8400000e -- IABT (current EL) CPU: 2 PID: 998 Comm: sh Not tainted 4.7.0-rc2+ #13 Hardware name: linux,dummy-virt (DT) task: ffff800077e35780 ti: ffff800077970000 task.ti: ffff800077970000 PC is at lkdtm_rodata_do_nothing+0x0/0x8 LR is at execute_location+0x74/0x88 The 'IABT (current EL)' indicates the error but it's a bit cryptic without knowledge of the ARM ARM. There is also no indication of the specific address which triggered the fault. The increase in kernel page permissions makes hitting this case more likely as well. Handling the case in the vectors gives a much more familiar looking error message: lkdtm: Performing direct entry EXEC_RODATA lkdtm: attempting ok execution at ffff0000084c0840 lkdtm: attempting bad execution at ffff000008880680 Unable to handle kernel paging request at virtual address ffff000008880680 pgd = ffff8000089b2000 [ffff000008880680] *pgd=00000000489b4003, *pud=0000000048904003, *pmd=0000000000000000 Internal error: Oops: 8400000e [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 997 Comm: sh Not tainted 4.7.0-rc1+ #24 Hardware name: linux,dummy-virt (DT) task: ffff800077f9f080 ti: ffff800008a1c000 task.ti: ffff800008a1c000 PC is at lkdtm_rodata_do_nothing+0x0/0x8 LR is at execute_location+0x74/0x88 Acked-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NLaura Abbott <labbott@redhat.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 27 7月, 2016 1 次提交
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由 Kirill A. Shutemov 提交于
We always have vma->vm_mm around. Link: http://lkml.kernel.org/r/1466021202-61880-8-git-send-email-kirill.shutemov@linux.intel.comSigned-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 19 7月, 2016 1 次提交
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由 Sandeepa Prabhu 提交于
Add support for basic kernel probes(kprobes) and jump probes (jprobes) for ARM64. Kprobes utilizes software breakpoint and single step debug exceptions supported on ARM v8. A software breakpoint is placed at the probe address to trap the kernel execution into the kprobe handler. ARM v8 supports enabling single stepping before the break exception return (ERET), with next PC in exception return address (ELR_EL1). The kprobe handler prepares an executable memory slot for out-of-line execution with a copy of the original instruction being probed, and enables single stepping. The PC is set to the out-of-line slot address before the ERET. With this scheme, the instruction is executed with the exact same register context except for the PC (and DAIF) registers. Debug mask (PSTATE.D) is enabled only when single stepping a recursive kprobe, e.g.: during kprobes reenter so that probed instruction can be single stepped within the kprobe handler -exception- context. The recursion depth of kprobe is always 2, i.e. upon probe re-entry, any further re-entry is prevented by not calling handlers and the case counted as a missed kprobe). Single stepping from the x-o-l slot has a drawback for PC-relative accesses like branching and symbolic literals access as the offset from the new PC (slot address) may not be ensured to fit in the immediate value of the opcode. Such instructions need simulation, so reject probing them. Instructions generating exceptions or cpu mode change are rejected for probing. Exclusive load/store instructions are rejected too. Additionally, the code is checked to see if it is inside an exclusive load/store sequence (code from Pratyush). System instructions are mostly enabled for stepping, except MSR/MRS accesses to "DAIF" flags in PSTATE, which are not safe for probing. This also changes arch/arm64/include/asm/ptrace.h to use include/asm-generic/ptrace.h. Thanks to Steve Capper and Pratyush Anand for several suggested Changes. Signed-off-by: NSandeepa Prabhu <sandeepa.s.prabhu@gmail.com> Signed-off-by: NDavid A. Long <dave.long@linaro.org> Signed-off-by: NPratyush Anand <panand@redhat.com> Acked-by: NMasami Hiramatsu <mhiramat@kernel.org> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 07 7月, 2016 1 次提交
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由 James Morse 提交于
If we take an exception while at EL1, the exception handler inherits the original context's addr_limit and PSTATE.UAO values. To be consistent always reset addr_limit and PSTATE.UAO on (re-)entry to EL1. This prevents accidental re-use of the original context's addr_limit. Based on a similar patch for arm from Russell King. Cc: <stable@vger.kernel.org> # 4.6- Acked-by: NWill Deacon <will.deacon@arm.com> Reviewed-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NJames Morse <james.morse@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 22 6月, 2016 2 次提交
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由 Mark Rutland 提交于
Currently we treat ESR_EL1 bit 24 as software-defined for distinguishing instruction aborts from data aborts, but this bit is architecturally RES0 for instruction aborts, and could be allocated for an arbitrary purpose in future. Additionally, we hard-code the value in entry.S without the mnemonic, making the code difficult to understand. Instead, remove ESR_LNX_EXEC, and distinguish aborts based on the esr, which we already pass to the sole use of ESR_LNX_EXEC. A new helper, is_el0_instruction_abort() is added to make the logic clear. Any instruction aborts taken from EL1 will already have been handled by bad_mode, so we need not handle that case in the helper. For consistency, the existing permission_fault helper is renamed to is_permission_fault, and the return type is changed to bool. There should be no functional changes as the return value was a boolean expression, and the result is only used in another boolean expression. Signed-off-by: NMark Rutland <mark.rutland@arm.com> Cc: Dave P Martin <dave.martin@arm.com> Cc: Huang Shijie <shijie.huang@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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由 Mark Rutland 提交于
Several places open-code extraction of the EC field from an ESR_ELx value, in subtly different ways. This is unfortunate duplication and variation, and the precise logic used to extract the field is a distraction. This patch adds a new macro, ESR_ELx_EC(), to extract the EC field from an ESR_ELx value in a consistent fashion. Existing open-coded extractions in core arm64 code are moved over to the new helper. KVM code is left as-is for the moment. Signed-off-by: NMark Rutland <mark.rutland@arm.com> Tested-by: NHuang Shijie <shijie.huang@arm.com> Cc: Dave P Martin <dave.martin@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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- 14 6月, 2016 1 次提交
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由 Mark Rutland 提交于
Unlike the debug_fault_info table, we never intentionally alter the fault_info table at runtime, and all derived pointers are treated as const currently. Make the table const so that it can be placed in .rodata and protected from unintentional writes, as we do for the syscall tables. Signed-off-by: NMark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 08 6月, 2016 1 次提交
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由 Will Deacon 提交于
Commit 66dbd6e6 ("arm64: Implement ptep_set_access_flags() for hardware AF/DBM") ensured that pte flags are updated atomically in the face of potential concurrent, hardware-assisted updates. However, Alex reports that: | This patch breaks swapping for me. | In the broken case, you'll see either systemd cpu time spike (because | it's stuck in a page fault loop) or the system hang (because the | application owning the screen is stuck in a page fault loop). It turns out that this is because the 'dirty' argument to ptep_set_access_flags is always 0 for read faults, and so we can't use it to set PTE_RDONLY. The failing sequence is: 1. We put down a PTE_WRITE | PTE_DIRTY | PTE_AF pte 2. Memory pressure -> pte_mkold(pte) -> clear PTE_AF 3. A read faults due to the missing access flag 4. ptep_set_access_flags is called with dirty = 0, due to the read fault 5. pte is then made PTE_WRITE | PTE_DIRTY | PTE_AF | PTE_RDONLY (!) 6. A write faults, but pte_write is true so we get stuck The solution is to check the new page table entry (as would be done by the generic, non-atomic definition of ptep_set_access_flags that just calls set_pte_at) to establish the dirty state. Cc: <stable@vger.kernel.org> # 4.3+ Fixes: 66dbd6e6 ("arm64: Implement ptep_set_access_flags() for hardware AF/DBM") Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com> Reported-by: NAlexander Graf <agraf@suse.de> Tested-by: NAlexander Graf <agraf@suse.de> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 19 4月, 2016 1 次提交
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由 Huang Shijie 提交于
We already re-enable interrupts where necessary in the entry code, so there is no need to do it again in do_page fault. This patch removes the redundant code. Acked-by: NCatalin Marinas <catalin.marinas@arm.com> Signed-off-by: NHuang Shijie <shijie.huang@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 16 4月, 2016 1 次提交
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由 Catalin Marinas 提交于
When hardware updates of the access and dirty states are enabled, the default ptep_set_access_flags() implementation based on calling set_pte_at() directly is potentially racy. This triggers the "racy dirty state clearing" warning in set_pte_at() because an existing writable PTE is overridden with a clean entry. There are two main scenarios for this situation: 1. The CPU getting an access fault does not support hardware updates of the access/dirty flags. However, a different agent in the system (e.g. SMMU) can do this, therefore overriding a writable entry with a clean one could potentially lose the automatically updated dirty status 2. A more complex situation is possible when all CPUs support hardware AF/DBM: a) Initial state: shareable + writable vma and pte_none(pte) b) Read fault taken by two threads of the same process on different CPUs c) CPU0 takes the mmap_sem and proceeds to handling the fault. It eventually reaches do_set_pte() which sets a writable + clean pte. CPU0 releases the mmap_sem d) CPU1 acquires the mmap_sem and proceeds to handle_pte_fault(). The pte entry it reads is present, writable and clean and it continues to pte_mkyoung() e) CPU1 calls ptep_set_access_flags() If between (d) and (e) the hardware (another CPU) updates the dirty state (clears PTE_RDONLY), CPU1 will override the PTR_RDONLY bit marking the entry clean again. This patch implements an arm64-specific ptep_set_access_flags() function to perform an atomic update of the PTE flags. Fixes: 2f4b829c ("arm64: Add support for hardware updates of the access and dirty pte bits") Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com> Reported-by: NMing Lei <tom.leiming@gmail.com> Tested-by: NJulien Grall <julien.grall@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: <stable@vger.kernel.org> # 4.3+ [will: reworded comment] Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 15 4月, 2016 1 次提交
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由 James Morse 提交于
With CONFIG_PROVE_LOCKING, CONFIG_DEBUG_LOCKDEP and CONFIG_TRACE_IRQFLAGS enabled, lockdep will compare current->hardirqs_enabled with the flags from local_irq_save(). When a debug exception occurs, interrupts are disabled in entry.S, but lockdep isn't told, resulting in: DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) ------------[ cut here ]------------ WARNING: at ../kernel/locking/lockdep.c:3523 Modules linked in: CPU: 3 PID: 1752 Comm: perf Not tainted 4.5.0-rc4+ #2204 Hardware name: ARM Juno development board (r1) (DT) task: ffffffc974868000 ti: ffffffc975f40000 task.ti: ffffffc975f40000 PC is at check_flags.part.35+0x17c/0x184 LR is at check_flags.part.35+0x17c/0x184 pc : [<ffffff80080fc93c>] lr : [<ffffff80080fc93c>] pstate: 600003c5 [...] ---[ end trace 74631f9305ef5020 ]--- Call trace: [<ffffff80080fc93c>] check_flags.part.35+0x17c/0x184 [<ffffff80080ffe30>] lock_acquire+0xa8/0xc4 [<ffffff8008093038>] breakpoint_handler+0x118/0x288 [<ffffff8008082434>] do_debug_exception+0x3c/0xa8 [<ffffff80080854b4>] el1_dbg+0x18/0x6c [<ffffff80081e82f4>] do_filp_open+0x64/0xdc [<ffffff80081d6e60>] do_sys_open+0x140/0x204 [<ffffff80081d6f58>] SyS_openat+0x10/0x18 [<ffffff8008085d30>] el0_svc_naked+0x24/0x28 possible reason: unannotated irqs-off. irq event stamp: 65857 hardirqs last enabled at (65857): [<ffffff80081fb1c0>] lookup_mnt+0xf4/0x1b4 hardirqs last disabled at (65856): [<ffffff80081fb188>] lookup_mnt+0xbc/0x1b4 softirqs last enabled at (65790): [<ffffff80080bdca4>] __do_softirq+0x1f8/0x290 softirqs last disabled at (65757): [<ffffff80080be038>] irq_exit+0x9c/0xd0 This patch adds the annotations to do_debug_exception(), while trying not to call trace_hardirqs_off() if el1_dbg() interrupted a task that already had irqs disabled. Signed-off-by: NJames Morse <james.morse@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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