diff options
Diffstat (limited to 'arch/arm64/kernel/probes/uprobes.c')
| -rw-r--r-- | arch/arm64/kernel/probes/uprobes.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/arch/arm64/kernel/probes/uprobes.c b/arch/arm64/kernel/probes/uprobes.c new file mode 100644 index 000000000000..941668800aea --- /dev/null +++ b/arch/arm64/kernel/probes/uprobes.c @@ -0,0 +1,229 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2014-2016 Pratyush Anand <panand@redhat.com> + */ +#include <linux/highmem.h> +#include <linux/ptrace.h> +#include <linux/uprobes.h> +#include <asm/cacheflush.h> +#include <asm/gcs.h> + +#include "decode-insn.h" + +#define UPROBE_INV_FAULT_CODE UINT_MAX + +void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, + void *src, unsigned long len) +{ + void *xol_page_kaddr = kmap_atomic(page); + void *dst = xol_page_kaddr + (vaddr & ~PAGE_MASK); + + /* + * Initial cache maintenance of the xol page done via set_pte_at(). + * Subsequent CMOs only needed if the xol slot changes. + */ + if (!memcmp(dst, src, len)) + goto done; + + /* Initialize the slot */ + memcpy(dst, src, len); + + /* flush caches (dcache/icache) */ + sync_icache_aliases((unsigned long)dst, (unsigned long)dst + len); + +done: + kunmap_atomic(xol_page_kaddr); +} + +unsigned long uprobe_get_swbp_addr(struct pt_regs *regs) +{ + return instruction_pointer(regs); +} + +int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, + unsigned long addr) +{ + u32 insn; + + /* TODO: Currently we do not support AARCH32 instruction probing */ + if (mm->context.flags & MMCF_AARCH32) + return -EOPNOTSUPP; + else if (!IS_ALIGNED(addr, AARCH64_INSN_SIZE)) + return -EINVAL; + + insn = le32_to_cpu(auprobe->insn); + + switch (arm_probe_decode_insn(insn, &auprobe->api)) { + case INSN_REJECTED: + return -EINVAL; + + case INSN_GOOD_NO_SLOT: + auprobe->simulate = true; + break; + + default: + break; + } + + return 0; +} + +int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct uprobe_task *utask = current->utask; + + /* Initialize with an invalid fault code to detect if ol insn trapped */ + current->thread.fault_code = UPROBE_INV_FAULT_CODE; + + /* Instruction points to execute ol */ + instruction_pointer_set(regs, utask->xol_vaddr); + + user_enable_single_step(current); + + return 0; +} + +int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct uprobe_task *utask = current->utask; + + WARN_ON_ONCE(current->thread.fault_code != UPROBE_INV_FAULT_CODE); + + /* Instruction points to execute next to breakpoint address */ + instruction_pointer_set(regs, utask->vaddr + 4); + + user_disable_single_step(current); + + return 0; +} +bool arch_uprobe_xol_was_trapped(struct task_struct *t) +{ + /* + * Between arch_uprobe_pre_xol and arch_uprobe_post_xol, if an xol + * insn itself is trapped, then detect the case with the help of + * invalid fault code which is being set in arch_uprobe_pre_xol + */ + if (t->thread.fault_code != UPROBE_INV_FAULT_CODE) + return true; + + return false; +} + +bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + u32 insn; + unsigned long addr; + + if (!auprobe->simulate) + return false; + + insn = le32_to_cpu(auprobe->insn); + addr = instruction_pointer(regs); + + if (auprobe->api.handler) + auprobe->api.handler(insn, addr, regs); + + return true; +} + +void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct uprobe_task *utask = current->utask; + + /* + * Task has received a fatal signal, so reset back to probed + * address. + */ + instruction_pointer_set(regs, utask->vaddr); + + user_disable_single_step(current); +} + +bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, + struct pt_regs *regs) +{ + /* + * If a simple branch instruction (B) was called for retprobed + * assembly label then return true even when regs->sp and ret->stack + * are same. It will ensure that cleanup and reporting of return + * instances corresponding to callee label is done when + * handle_trampoline for called function is executed. + */ + if (ctx == RP_CHECK_CHAIN_CALL) + return regs->sp <= ret->stack; + else + return regs->sp < ret->stack; +} + +unsigned long +arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, + struct pt_regs *regs) +{ + unsigned long orig_ret_vaddr; + unsigned long gcs_ret_vaddr; + int err = 0; + u64 gcspr; + + orig_ret_vaddr = procedure_link_pointer(regs); + + if (task_gcs_el0_enabled(current)) { + gcspr = read_sysreg_s(SYS_GCSPR_EL0); + gcs_ret_vaddr = get_user_gcs((__force unsigned long __user *)gcspr, &err); + if (err) { + force_sig(SIGSEGV); + goto out; + } + + /* + * If the LR and GCS return addr don't match, then some kind of PAC + * signing or control flow occurred since entering the probed function. + * Likely because the user is attempting to retprobe on an instruction + * that isn't a function boundary or inside a leaf function. Explicitly + * abort this retprobe because it will generate a GCS exception. + */ + if (gcs_ret_vaddr != orig_ret_vaddr) { + orig_ret_vaddr = -1; + goto out; + } + + put_user_gcs(trampoline_vaddr, (__force unsigned long __user *)gcspr, &err); + if (err) { + force_sig(SIGSEGV); + goto out; + } + } + + /* Replace the return addr with trampoline addr */ + procedure_link_pointer_set(regs, trampoline_vaddr); + +out: + return orig_ret_vaddr; +} + +int arch_uprobe_exception_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + return NOTIFY_DONE; +} + +int uprobe_brk_handler(struct pt_regs *regs, + unsigned long esr) +{ + if (uprobe_pre_sstep_notifier(regs)) + return DBG_HOOK_HANDLED; + + return DBG_HOOK_ERROR; +} + +int uprobe_single_step_handler(struct pt_regs *regs, + unsigned long esr) +{ + struct uprobe_task *utask = current->utask; + + WARN_ON(utask && (instruction_pointer(regs) != utask->xol_vaddr + 4)); + if (uprobe_post_sstep_notifier(regs)) + return DBG_HOOK_HANDLED; + + return DBG_HOOK_ERROR; +} + |