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* arm64: Call __show_regs directlyKefeng Wang2017-05-301-2/+2
| | | | | | | | | | | | | | | | | 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: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: kprobes: remove kprobe_exceptions_notifyNaveen N. Rao2017-03-101-6/+0
| | | | | | | | | | Commit fc62d0207ae0 ("kprobes: Introduce weak variant of kprobe_exceptions_notify()") introduces a generic empty version of the function for architectures that don't need special handling, like arm64. As such, remove the arch/arm64/ specific handler. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-0/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/debug.h> 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: Linus 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: Ingo Molnar <mingo@kernel.org>
* Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds2016-12-241-1/+1
| | | | | | | | | | | | | This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* arm64: kprobe: protect/rename few definitions to be reused by uprobePratyush Anand2016-11-071-18/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | decode-insn code has to be reused by arm64 uprobe implementation as well. Therefore, this patch protects some portion of kprobe code and renames few other, so that decode-insn functionality can be reused by uprobe even when CONFIG_KPROBES is not defined. kprobe_opcode_t and struct arch_specific_insn are also defined by linux/kprobes.h, when CONFIG_KPROBES is not defined. So, protect these definitions in asm/probes.h. linux/kprobes.h already includes asm/kprobes.h. Therefore, remove inclusion of asm/kprobes.h from decode-insn.c. There are some definitions like kprobe_insn and kprobes_handler_t etc can be re-used by uprobe. So, it would be better to remove 'k' from their names. struct arch_specific_insn is specific to kprobe. Therefore, introduce a new struct arch_probe_insn which will be common for both kprobe and uprobe, so that decode-insn code can be shared. Modify kprobe code accordingly. Function arm_probe_decode_insn() will be needed by uprobe as well. So make it global. Signed-off-by: Pratyush Anand <panand@redhat.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: migrate exception table users off module.h and onto extable.hPaul Gortmaker2016-09-201-1/+1
| | | | | | | | | | | | | | | 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: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: Create sections.hJames Morse2016-08-251-4/+1
| | | | | | | | | | | | | | | Each time new section markers are added, kernel/vmlinux.ld.S is updated, and new extern char __start_foo[] definitions are scattered through the tree. Create asm/include/sections.h to collect these definitions (and include the existing asm-generic version). Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: kprobe: Always clear pstate.D in breakpoint exception handlerPratyush Anand2016-08-251-16/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Whenever we are hitting a kprobe from a none-kprobe debug exception handler, we hit an infinite occurrences of "Unexpected kernel single-step exception at EL1" PSTATE.D is debug exception mask bit. It is set whenever we enter into an exception mode. When it is set then Watchpoint, Breakpoint, and Software Step exceptions are masked. However, software Breakpoint Instruction exceptions can never be masked. Therefore, if we ever execute a BRK instruction, irrespective of D-bit setting, we will be receiving a corresponding breakpoint exception. For example: - We are executing kprobe pre/post handler, and kprobe has been inserted in one of the instruction of a function called by handler. So, it executes BRK instruction and we land into the case of KPROBE_REENTER. (This case is already handled by current code) - We are executing uprobe handler or any other BRK handler such as in WARN_ON (BRK BUG_BRK_IMM), and we trace that path using kprobe.So, we enter into kprobe breakpoint handler,from another BRK handler.(This case is not being handled currently) In all such cases kprobe breakpoint exception will be raised when we were already in debug exception mode. SPSR's D bit (bit 9) shows the value of PSTATE.D immediately before the exception was taken. So, in above example cases we would find it set in kprobe breakpoint handler. Single step exception will always be followed by a kprobe breakpoint exception.However, it will only be raised gracefully if we clear D bit while returning from breakpoint exception. If D bit is set then, it results into undefined exception and when it's handler enables dbg then single step exception is generated, however it will never be handled(because address does not match and therefore treated as unexpected). This patch clears D-flag unconditionally in setup_singlestep, so that we can always get single step exception correctly after returning from breakpoint exception. Additionally, it also removes D-flag set statement for KPROBE_REENTER return path, because debug exception for KPROBE_REENTER will always take place in a debug exception state. So, D-flag will already be set in this case. Acked-by: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Pratyush Anand <panand@redhat.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: Remove stack duplicating code from jprobesDavid A. Long2016-08-111-26/+5
| | | | | | | | | | | | | | | Because the arm64 calling standard allows stacked function arguments to be anywhere in the stack frame, do not attempt to duplicate the stack frame for jprobes handler functions. Documentation changes to describe this issue have been broken out into a separate patch in order to simultaneously address them in other architecture(s). Signed-off-by: David A. Long <dave.long@linaro.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: kprobes: Add KASAN instrumentation around stack accessesCatalin Marinas2016-07-211-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | This patch disables KASAN around the memcpy from/to the kernel or IRQ stacks to avoid warnings like below: BUG: KASAN: stack-out-of-bounds in setjmp_pre_handler+0xe4/0x170 at addr ffff800935cbbbc0 Read of size 128 by task swapper/0/1 page:ffff7e0024d72ec0 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x1000000000000000() page dumped because: kasan: bad access detected CPU: 4 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc4+ #1 Hardware name: ARM Juno development board (r0) (DT) Call trace: [<ffff20000808ad88>] dump_backtrace+0x0/0x280 [<ffff20000808b01c>] show_stack+0x14/0x20 [<ffff200008563a64>] dump_stack+0xa4/0xc8 [<ffff20000824a1fc>] kasan_report_error+0x4fc/0x528 [<ffff20000824a5e8>] kasan_report+0x40/0x48 [<ffff20000824948c>] check_memory_region+0x144/0x1a0 [<ffff200008249814>] memcpy+0x34/0x68 [<ffff200008c3ee2c>] setjmp_pre_handler+0xe4/0x170 [<ffff200008c3ec5c>] kprobe_breakpoint_handler+0xec/0x1d8 [<ffff2000080853a4>] brk_handler+0x5c/0xa0 [<ffff2000080813f0>] do_debug_exception+0xa0/0x138 Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: kprobes: Cleanup jprobe_returnMarc Zyngier2016-07-211-12/+10
| | | | | | | | | | | | | | | | | | | | | | jprobe_return seems to have aged badly. Comments referring to non-existent behaviours, and a dangerous habit of messing with registers without telling the compiler. This patches applies the following remedies: - Fix the comments to describe the actual behaviour - Tidy up the asm sequence to directly assign the stack pointer without clobbering extra registers - Mark the rest of the function as unreachable() so that the compiler knows that there is no need for an epilogue - Stop making jprobe_return_break a global function (you really don't want to call that guy, and it isn't even a function). Tested with tcp_probe. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: kprobes: Fix overflow when saving stackMarc Zyngier2016-07-201-8/+14
| | | | | | | | | | | | | | | The MIN_STACK_SIZE macro tries evaluate how much stack space needs to be saved in the jprobes_stack array, sized at 128 bytes. When using the IRQ stack, said macro can happily return up to IRQ_STACK_SIZE, which is 16kB. Mayhem follows. This patch fixes things by getting rid of the crazy macro and limiting the copy to be at most the size of the jprobes_stack array, no matter which stack we're on. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: kprobes: WARN if attempting to step with PSTATE.D=1Will Deacon2016-07-191-0/+2
| | | | | | | | | | | Stepping with PSTATE.D=1 is bad news. The step won't generate a debug exception and we'll likely walk off into random data structures. This should never happen, but when it does, it's a PITA to debug. Add a WARN_ON to shout if we realise this is about to take place. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: Add kernel return probes support (kretprobes)Sandeepa Prabhu2016-07-191-1/+89
| | | | | | | | | | | | The pre-handler of this special 'trampoline' kprobe executes the return probe handler functions and restores original return address in ELR_EL1. This way the saved pt_regs still hold the original register context to be carried back to the probed kernel function. Signed-off-by: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com> Signed-off-by: David A. Long <dave.long@linaro.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: Add trampoline code for kretprobesWilliam Cohen2016-07-191-0/+5
| | | | | | | | | | | | | | | | The trampoline code is used by kretprobes to capture a return from a probed function. This is done by saving the registers, calling the handler, and restoring the registers. The code then returns to the original saved caller return address. It is necessary to do this directly instead of using a software breakpoint because the code used in processing that breakpoint could itself be kprobe'd and cause a problematic reentry into the debug exception handler. Signed-off-by: William Cohen <wcohen@redhat.com> Signed-off-by: David A. Long <dave.long@linaro.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> [catalin.marinas@arm.com: removed unnecessary masking of the PSTATE bits] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: kprobes instruction simulation supportSandeepa Prabhu2016-07-191-11/+42
| | | | | | | | | | | | | | | | | | | | | | | | Kprobes needs simulation of instructions that cannot be stepped from a different memory location, e.g.: those instructions that uses PC-relative addressing. In simulation, the behaviour of the instruction is implemented using a copy of pt_regs. The following instruction categories are simulated: - All branching instructions(conditional, register, and immediate) - Literal access instructions(load-literal, adr/adrp) Conditional execution is limited to branching instructions in ARM v8. If conditions at PSTATE do not match the condition fields of opcode, the instruction is effectively NOP. Thanks to Will Cohen for assorted suggested changes. Signed-off-by: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com> Signed-off-by: William Cohen <wcohen@redhat.com> Signed-off-by: David A. Long <dave.long@linaro.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> [catalin.marinas@arm.com: removed linux/module.h include] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: Treat all entry code as non-kprobe-ablePratyush Anand2016-07-191-0/+26
| | | | | | | | | | Entry symbols are not kprobe safe. So blacklist them for kprobing. Signed-off-by: Pratyush Anand <panand@redhat.com> Signed-off-by: David A. Long <dave.long@linaro.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> [catalin.marinas@arm.com: Do not include syscall wrappers in .entry.text] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: Kprobes with single stepping supportSandeepa Prabhu2016-07-191-0/+525
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: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com> Signed-off-by: David A. Long <dave.long@linaro.org> Signed-off-by: Pratyush Anand <panand@redhat.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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