^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * User-space Probes (UProbes) for powerpc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) * Copyright IBM Corporation, 2007-2012
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) * Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@in.ibm.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) #include <linux/kernel.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/sched.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <linux/ptrace.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <linux/uprobes.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include <linux/uaccess.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include <linux/kdebug.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) #include <asm/sstep.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #include <asm/inst.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) #define UPROBE_TRAP_NR UINT_MAX
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) * is_trap_insn - check if the instruction is a trap variant
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) * @insn: instruction to be checked.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) * Returns true if @insn is a trap variant.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) bool is_trap_insn(uprobe_opcode_t *insn)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) return (is_trap(*insn));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) * arch_uprobe_analyze_insn
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) * @mm: the probed address space.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) * @arch_uprobe: the probepoint information.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) * @addr: vaddr to probe.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) * Return 0 on success or a -ve number on error.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) struct mm_struct *mm, unsigned long addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) if (addr & 0x03)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) * arch_uprobe_pre_xol - prepare to execute out of line.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) * @auprobe: the probepoint information.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) * @regs: reflects the saved user state of current task.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) struct arch_uprobe_task *autask = ¤t->utask->autask;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) autask->saved_trap_nr = current->thread.trap_nr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) current->thread.trap_nr = UPROBE_TRAP_NR;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) regs->nip = current->utask->xol_vaddr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) user_enable_single_step(current);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) * @regs: Reflects the saved state of the task after it has hit a breakpoint
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) * instruction.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) * Return the address of the breakpoint instruction.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) return instruction_pointer(regs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) * If xol insn itself traps and generates a signal (SIGILL/SIGSEGV/etc),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) * then detect the case where a singlestepped instruction jumps back to its
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) * own address. It is assumed that anything like do_page_fault/do_trap/etc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) * sets thread.trap_nr != UINT_MAX.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) * arch_uprobe_pre_xol/arch_uprobe_post_xol save/restore thread.trap_nr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) * arch_uprobe_xol_was_trapped() simply checks that ->trap_nr is not equal to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) * UPROBE_TRAP_NR == UINT_MAX set by arch_uprobe_pre_xol().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) bool arch_uprobe_xol_was_trapped(struct task_struct *t)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) if (t->thread.trap_nr != UPROBE_TRAP_NR)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) * Called after single-stepping. To avoid the SMP problems that can
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) * occur when we temporarily put back the original opcode to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) * single-step, we single-stepped a copy of the instruction.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) * This function prepares to resume execution after the single-step.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) struct uprobe_task *utask = current->utask;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) current->thread.trap_nr = utask->autask.saved_trap_nr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) * On powerpc, except for loads and stores, most instructions
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) * including ones that alter code flow (branches, calls, returns)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) * are emulated in the kernel. We get here only if the emulation
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) * support doesn't exist and have to fix-up the next instruction
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) * to be executed.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) regs->nip = (unsigned long)ppc_inst_next((void *)utask->vaddr, &auprobe->insn);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) user_disable_single_step(current);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) /* callback routine for handling exceptions. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) int arch_uprobe_exception_notify(struct notifier_block *self,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) unsigned long val, void *data)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) struct die_args *args = data;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) struct pt_regs *regs = args->regs;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) /* regs == NULL is a kernel bug */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) if (WARN_ON(!regs))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) return NOTIFY_DONE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) /* We are only interested in userspace traps */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) if (!user_mode(regs))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) return NOTIFY_DONE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) switch (val) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) case DIE_BPT:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) if (uprobe_pre_sstep_notifier(regs))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) return NOTIFY_STOP;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) case DIE_SSTEP:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) if (uprobe_post_sstep_notifier(regs))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) return NOTIFY_STOP;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) default:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) return NOTIFY_DONE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) * This function gets called when XOL instruction either gets trapped or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) * the thread has a fatal signal, so reset the instruction pointer to its
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) * probed address.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) struct uprobe_task *utask = current->utask;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) current->thread.trap_nr = utask->autask.saved_trap_nr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) instruction_pointer_set(regs, utask->vaddr);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) user_disable_single_step(current);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) * See if the instruction can be emulated.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) * Returns true if instruction was emulated, false otherwise.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) * emulate_step() returns 1 if the insn was successfully emulated.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) * For all other cases, we need to single-step in hardware.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) ret = emulate_step(regs, ppc_inst_read(&auprobe->insn));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) if (ret > 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) unsigned long
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) unsigned long orig_ret_vaddr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) orig_ret_vaddr = regs->link;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) /* Replace the return addr with trampoline addr */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) regs->link = trampoline_vaddr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) return orig_ret_vaddr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) if (ctx == RP_CHECK_CHAIN_CALL)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) return regs->gpr[1] <= ret->stack;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) return regs->gpr[1] < ret->stack;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) }
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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