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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-07 19:34:17 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-07 19:34:17 -0700 |
commit | d3511f53bb2475f2a4e8460bee5a1ae6dea2a433 (patch) | |
tree | 8141260e4fb705d8f94548150572433c685e6829 /arch/parisc/kernel/kprobes.c | |
parent | 02aff8db6438ce29371fd9cd54c57213f4bb4536 (diff) | |
parent | 62217beb394e654bbd2bb87c533dadd2d8bf62c6 (diff) | |
download | linux-d3511f53bb2475f2a4e8460bee5a1ae6dea2a433.tar.gz linux-d3511f53bb2475f2a4e8460bee5a1ae6dea2a433.tar.bz2 linux-d3511f53bb2475f2a4e8460bee5a1ae6dea2a433.zip |
Merge branch 'parisc-5.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
Pull parisc updates from Helge Deller:
"Many great new features, fixes and optimizations, including:
- Convert page table updates to use per-pagetable spinlocks which
overall improves performance on SMP machines a lot, by Mikulas
Patocka
- Kernel debugger (KGDB) support, by Sven Schnelle
- KPROBES support, by Sven Schnelle
- Lots of TLB lock/flush improvements, by Dave Anglin
- Drop DISCONTIGMEM and switch to SPARSEMEM
- Added JUMP_LABEL, branch runtime-patching support
- Lots of other small speedups and cleanups, e.g. for QEMU, stack
randomization, avoidance of name clashes, documentation updates,
etc ..."
* 'parisc-5.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: (28 commits)
parisc: Add static branch and JUMP_LABEL feature
parisc: Use PA_ASM_LEVEL in boot code
parisc: Rename LEVEL to PA_ASM_LEVEL to avoid name clash with DRBD code
parisc: Update huge TLB page support to use per-pagetable spinlock
parisc: Use per-pagetable spinlock
parisc: Allow live-patching of __meminit functions
parisc: Add memory barrier to asm pdc and sync instructions
parisc: Add memory clobber to TLB purges
parisc: Use ldcw instruction for SMP spinlock release barrier
parisc: Remove lock code to serialize TLB operations in pacache.S
parisc: Switch from DISCONTIGMEM to SPARSEMEM
parisc: enable wide mode early
parisc: update feature lists
parisc: Show n/a if product number not available
parisc: remove unused flags parameter in __patch_text()
doc: update kprobes supported architecture list
parisc: Implement kretprobes
parisc: remove kprobes.h from generic-y
parisc: Implement kprobes
parisc: add functions required by KPROBE_EVENTS
...
Diffstat (limited to 'arch/parisc/kernel/kprobes.c')
-rw-r--r-- | arch/parisc/kernel/kprobes.c | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/arch/parisc/kernel/kprobes.c b/arch/parisc/kernel/kprobes.c new file mode 100644 index 000000000000..d58960b33bda --- /dev/null +++ b/arch/parisc/kernel/kprobes.c @@ -0,0 +1,291 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * arch/parisc/kernel/kprobes.c + * + * PA-RISC kprobes implementation + * + * Copyright (c) 2019 Sven Schnelle <svens@stackframe.org> + */ + +#include <linux/types.h> +#include <linux/kprobes.h> +#include <linux/slab.h> +#include <asm/cacheflush.h> +#include <asm/patch.h> + +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + if ((unsigned long)p->addr & 3UL) + return -EINVAL; + + p->ainsn.insn = get_insn_slot(); + if (!p->ainsn.insn) + return -ENOMEM; + + memcpy(p->ainsn.insn, p->addr, + MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + p->opcode = *p->addr; + flush_insn_slot(p); + return 0; +} + +void __kprobes arch_remove_kprobe(struct kprobe *p) +{ + if (!p->ainsn.insn) + return; + + free_insn_slot(p->ainsn.insn, 0); + p->ainsn.insn = NULL; +} + +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, PARISC_KPROBES_BREAK_INSN); +} + +void __kprobes arch_disarm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, p->opcode); +} + +static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + kcb->prev_kprobe.kp = kprobe_running(); + kcb->prev_kprobe.status = kcb->kprobe_status; +} + +static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); + kcb->kprobe_status = kcb->prev_kprobe.status; +} + +static inline void __kprobes set_current_kprobe(struct kprobe *p) +{ + __this_cpu_write(current_kprobe, p); +} + +static void __kprobes setup_singlestep(struct kprobe *p, + struct kprobe_ctlblk *kcb, struct pt_regs *regs) +{ + kcb->iaoq[0] = regs->iaoq[0]; + kcb->iaoq[1] = regs->iaoq[1]; + regs->iaoq[0] = (unsigned long)p->ainsn.insn; + mtctl(0, 0); + regs->gr[0] |= PSW_R; +} + +int __kprobes parisc_kprobe_break_handler(struct pt_regs *regs) +{ + struct kprobe *p; + struct kprobe_ctlblk *kcb; + + preempt_disable(); + + kcb = get_kprobe_ctlblk(); + p = get_kprobe((unsigned long *)regs->iaoq[0]); + + if (!p) { + preempt_enable_no_resched(); + return 0; + } + + if (kprobe_running()) { + /* + * We have reentered the kprobe_handler, since another kprobe + * was hit while within the handler, we save the original + * kprobes and single step on the instruction of the new probe + * without calling any user handlers to avoid recursive + * kprobes. + */ + save_previous_kprobe(kcb); + set_current_kprobe(p); + kprobes_inc_nmissed_count(p); + setup_singlestep(p, kcb, regs); + kcb->kprobe_status = KPROBE_REENTER; + return 1; + } + + set_current_kprobe(p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + + /* If we have no pre-handler or it returned 0, we continue with + * normal processing. If we have a pre-handler and it returned + * non-zero - which means user handler setup registers to exit + * to another instruction, we must skip the single stepping. + */ + + if (!p->pre_handler || !p->pre_handler(p, regs)) { + setup_singlestep(p, kcb, regs); + kcb->kprobe_status = KPROBE_HIT_SS; + } else { + reset_current_kprobe(); + preempt_enable_no_resched(); + } + return 1; +} + +int __kprobes parisc_kprobe_ss_handler(struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + struct kprobe *p = kprobe_running(); + + if (regs->iaoq[0] != (unsigned long)p->ainsn.insn+4) + return 0; + + /* restore back original saved kprobe variables and continue */ + if (kcb->kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(kcb); + return 1; + } + + /* for absolute branch instructions we can copy iaoq_b. for relative + * branch instructions we need to calculate the new address based on the + * difference between iaoq_f and iaoq_b. We cannot use iaoq_b without + * modificationt because it's based on our ainsn.insn address. + */ + + if (p->post_handler) + p->post_handler(p, regs, 0); + + switch (regs->iir >> 26) { + case 0x38: /* BE */ + case 0x39: /* BE,L */ + case 0x3a: /* BV */ + case 0x3b: /* BVE */ + /* for absolute branches, regs->iaoq[1] has already the right + * address + */ + regs->iaoq[0] = kcb->iaoq[1]; + break; + default: + regs->iaoq[1] = kcb->iaoq[0]; + regs->iaoq[1] += (regs->iaoq[1] - regs->iaoq[0]) + 4; + regs->iaoq[0] = kcb->iaoq[1]; + break; + } + kcb->kprobe_status = KPROBE_HIT_SSDONE; + reset_current_kprobe(); + return 1; +} + +static inline void kretprobe_trampoline(void) +{ + asm volatile("nop"); + asm volatile("nop"); +} + +static int __kprobes trampoline_probe_handler(struct kprobe *p, + struct pt_regs *regs); + +static struct kprobe trampoline_p = { + .pre_handler = trampoline_probe_handler +}; + +static int __kprobes trampoline_probe_handler(struct kprobe *p, + struct pt_regs *regs) +{ + struct kretprobe_instance *ri = NULL; + struct hlist_head *head, empty_rp; + struct hlist_node *tmp; + unsigned long flags, orig_ret_address = 0; + unsigned long trampoline_address = (unsigned long)trampoline_p.addr; + kprobe_opcode_t *correct_ret_addr = NULL; + + INIT_HLIST_HEAD(&empty_rp); + kretprobe_hash_lock(current, &head, &flags); + + /* + * It is possible to have multiple instances associated with a given + * task either because multiple functions in the call path have + * a return probe installed on them, and/or more than one return + * probe was registered for a target function. + * + * We can handle this because: + * - instances are always inserted at the head of the list + * - when multiple return probes are registered for the same + * function, the first instance's ret_addr will point to the + * real return address, and all the rest will point to + * kretprobe_trampoline + */ + hlist_for_each_entry_safe(ri, tmp, head, hlist) { + if (ri->task != current) + /* another task is sharing our hash bucket */ + continue; + + orig_ret_address = (unsigned long)ri->ret_addr; + + if (orig_ret_address != trampoline_address) + /* + * This is the real return address. Any other + * instances associated with this task are for + * other calls deeper on the call stack + */ + break; + } + + kretprobe_assert(ri, orig_ret_address, trampoline_address); + + correct_ret_addr = ri->ret_addr; + hlist_for_each_entry_safe(ri, tmp, head, hlist) { + if (ri->task != current) + /* another task is sharing our hash bucket */ + continue; + + orig_ret_address = (unsigned long)ri->ret_addr; + if (ri->rp && ri->rp->handler) { + __this_cpu_write(current_kprobe, &ri->rp->kp); + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; + ri->ret_addr = correct_ret_addr; + ri->rp->handler(ri, regs); + __this_cpu_write(current_kprobe, NULL); + } + + recycle_rp_inst(ri, &empty_rp); + + if (orig_ret_address != trampoline_address) + /* + * This is the real return address. Any other + * instances associated with this task are for + * other calls deeper on the call stack + */ + break; + } + + kretprobe_hash_unlock(current, &flags); + + hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { + hlist_del(&ri->hlist); + kfree(ri); + } + instruction_pointer_set(regs, orig_ret_address); + return 1; +} + +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *)regs->gr[2]; + + /* Replace the return addr with trampoline addr. */ + regs->gr[2] = (unsigned long)trampoline_p.addr; +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + return p->addr == trampoline_p.addr; +} +bool arch_kprobe_on_func_entry(unsigned long offset) +{ + return !offset; +} + +int __init arch_init_kprobes(void) +{ + trampoline_p.addr = (kprobe_opcode_t *) + dereference_function_descriptor(kretprobe_trampoline); + return register_kprobe(&trampoline_p); +} |