From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- arch/arm/kernel/unwind.c | 608 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 608 insertions(+) create mode 100644 arch/arm/kernel/unwind.c (limited to 'arch/arm/kernel/unwind.c') diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c new file mode 100644 index 0000000000..9d21921560 --- /dev/null +++ b/arch/arm/kernel/unwind.c @@ -0,0 +1,608 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * arch/arm/kernel/unwind.c + * + * Copyright (C) 2008 ARM Limited + * + * Stack unwinding support for ARM + * + * An ARM EABI version of gcc is required to generate the unwind + * tables. For information about the structure of the unwind tables, + * see "Exception Handling ABI for the ARM Architecture" at: + * + * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html + */ + +#ifndef __CHECKER__ +#if !defined (__ARM_EABI__) +#warning Your compiler does not have EABI support. +#warning ARM unwind is known to compile only with EABI compilers. +#warning Change compiler or disable ARM_UNWIND option. +#endif +#endif /* __CHECKER__ */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#include "reboot.h" + +/* Dummy functions to avoid linker complaints */ +void __aeabi_unwind_cpp_pr0(void) +{ +}; +EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0); + +void __aeabi_unwind_cpp_pr1(void) +{ +}; +EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1); + +void __aeabi_unwind_cpp_pr2(void) +{ +}; +EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2); + +struct unwind_ctrl_block { + unsigned long vrs[16]; /* virtual register set */ + const unsigned long *insn; /* pointer to the current instructions word */ + unsigned long sp_high; /* highest value of sp allowed */ + unsigned long *lr_addr; /* address of LR value on the stack */ + /* + * 1 : check for stack overflow for each register pop. + * 0 : save overhead if there is plenty of stack remaining. + */ + int check_each_pop; + int entries; /* number of entries left to interpret */ + int byte; /* current byte number in the instructions word */ +}; + +enum regs { +#ifdef CONFIG_THUMB2_KERNEL + FP = 7, +#else + FP = 11, +#endif + SP = 13, + LR = 14, + PC = 15 +}; + +extern const struct unwind_idx __start_unwind_idx[]; +static const struct unwind_idx *__origin_unwind_idx; +extern const struct unwind_idx __stop_unwind_idx[]; + +static DEFINE_RAW_SPINLOCK(unwind_lock); +static LIST_HEAD(unwind_tables); + +/* Convert a prel31 symbol to an absolute address */ +#define prel31_to_addr(ptr) \ +({ \ + /* sign-extend to 32 bits */ \ + long offset = (((long)*(ptr)) << 1) >> 1; \ + (unsigned long)(ptr) + offset; \ +}) + +/* + * Binary search in the unwind index. The entries are + * guaranteed to be sorted in ascending order by the linker. + * + * start = first entry + * origin = first entry with positive offset (or stop if there is no such entry) + * stop - 1 = last entry + */ +static const struct unwind_idx *search_index(unsigned long addr, + const struct unwind_idx *start, + const struct unwind_idx *origin, + const struct unwind_idx *stop) +{ + unsigned long addr_prel31; + + pr_debug("%s(%08lx, %p, %p, %p)\n", + __func__, addr, start, origin, stop); + + /* + * only search in the section with the matching sign. This way the + * prel31 numbers can be compared as unsigned longs. + */ + if (addr < (unsigned long)start) + /* negative offsets: [start; origin) */ + stop = origin; + else + /* positive offsets: [origin; stop) */ + start = origin; + + /* prel31 for address relavive to start */ + addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff; + + while (start < stop - 1) { + const struct unwind_idx *mid = start + ((stop - start) >> 1); + + /* + * As addr_prel31 is relative to start an offset is needed to + * make it relative to mid. + */ + if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) < + mid->addr_offset) + stop = mid; + else { + /* keep addr_prel31 relative to start */ + addr_prel31 -= ((unsigned long)mid - + (unsigned long)start); + start = mid; + } + } + + if (likely(start->addr_offset <= addr_prel31)) + return start; + else { + pr_warn("unwind: Unknown symbol address %08lx\n", addr); + return NULL; + } +} + +static const struct unwind_idx *unwind_find_origin( + const struct unwind_idx *start, const struct unwind_idx *stop) +{ + pr_debug("%s(%p, %p)\n", __func__, start, stop); + while (start < stop) { + const struct unwind_idx *mid = start + ((stop - start) >> 1); + + if (mid->addr_offset >= 0x40000000) + /* negative offset */ + start = mid + 1; + else + /* positive offset */ + stop = mid; + } + pr_debug("%s -> %p\n", __func__, stop); + return stop; +} + +static const struct unwind_idx *unwind_find_idx(unsigned long addr) +{ + const struct unwind_idx *idx = NULL; + unsigned long flags; + + pr_debug("%s(%08lx)\n", __func__, addr); + + if (core_kernel_text(addr)) { + if (unlikely(!__origin_unwind_idx)) + __origin_unwind_idx = + unwind_find_origin(__start_unwind_idx, + __stop_unwind_idx); + + /* main unwind table */ + idx = search_index(addr, __start_unwind_idx, + __origin_unwind_idx, + __stop_unwind_idx); + } else { + /* module unwind tables */ + struct unwind_table *table; + + raw_spin_lock_irqsave(&unwind_lock, flags); + list_for_each_entry(table, &unwind_tables, list) { + if (addr >= table->begin_addr && + addr < table->end_addr) { + idx = search_index(addr, table->start, + table->origin, + table->stop); + /* Move-to-front to exploit common traces */ + list_move(&table->list, &unwind_tables); + break; + } + } + raw_spin_unlock_irqrestore(&unwind_lock, flags); + } + + pr_debug("%s: idx = %p\n", __func__, idx); + return idx; +} + +static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl) +{ + unsigned long ret; + + if (ctrl->entries <= 0) { + pr_warn("unwind: Corrupt unwind table\n"); + return 0; + } + + ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff; + + if (ctrl->byte == 0) { + ctrl->insn++; + ctrl->entries--; + ctrl->byte = 3; + } else + ctrl->byte--; + + return ret; +} + +/* Before poping a register check whether it is feasible or not */ +static int unwind_pop_register(struct unwind_ctrl_block *ctrl, + unsigned long **vsp, unsigned int reg) +{ + if (unlikely(ctrl->check_each_pop)) + if (*vsp >= (unsigned long *)ctrl->sp_high) + return -URC_FAILURE; + + /* Use READ_ONCE_NOCHECK here to avoid this memory access + * from being tracked by KASAN. + */ + ctrl->vrs[reg] = READ_ONCE_NOCHECK(*(*vsp)); + if (reg == 14) + ctrl->lr_addr = *vsp; + (*vsp)++; + return URC_OK; +} + +/* Helper functions to execute the instructions */ +static int unwind_exec_pop_subset_r4_to_r13(struct unwind_ctrl_block *ctrl, + unsigned long mask) +{ + unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; + int load_sp, reg = 4; + + load_sp = mask & (1 << (13 - 4)); + while (mask) { + if (mask & 1) + if (unwind_pop_register(ctrl, &vsp, reg)) + return -URC_FAILURE; + mask >>= 1; + reg++; + } + if (!load_sp) { + ctrl->vrs[SP] = (unsigned long)vsp; + } + + return URC_OK; +} + +static int unwind_exec_pop_r4_to_rN(struct unwind_ctrl_block *ctrl, + unsigned long insn) +{ + unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; + int reg; + + /* pop R4-R[4+bbb] */ + for (reg = 4; reg <= 4 + (insn & 7); reg++) + if (unwind_pop_register(ctrl, &vsp, reg)) + return -URC_FAILURE; + + if (insn & 0x8) + if (unwind_pop_register(ctrl, &vsp, 14)) + return -URC_FAILURE; + + ctrl->vrs[SP] = (unsigned long)vsp; + + return URC_OK; +} + +static int unwind_exec_pop_subset_r0_to_r3(struct unwind_ctrl_block *ctrl, + unsigned long mask) +{ + unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; + int reg = 0; + + /* pop R0-R3 according to mask */ + while (mask) { + if (mask & 1) + if (unwind_pop_register(ctrl, &vsp, reg)) + return -URC_FAILURE; + mask >>= 1; + reg++; + } + ctrl->vrs[SP] = (unsigned long)vsp; + + return URC_OK; +} + +static unsigned long unwind_decode_uleb128(struct unwind_ctrl_block *ctrl) +{ + unsigned long bytes = 0; + unsigned long insn; + unsigned long result = 0; + + /* + * unwind_get_byte() will advance `ctrl` one instruction at a time, so + * loop until we get an instruction byte where bit 7 is not set. + * + * Note: This decodes a maximum of 4 bytes to output 28 bits data where + * max is 0xfffffff: that will cover a vsp increment of 1073742336, hence + * it is sufficient for unwinding the stack. + */ + do { + insn = unwind_get_byte(ctrl); + result |= (insn & 0x7f) << (bytes * 7); + bytes++; + } while (!!(insn & 0x80) && (bytes != sizeof(result))); + + return result; +} + +/* + * Execute the current unwind instruction. + */ +static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) +{ + unsigned long insn = unwind_get_byte(ctrl); + int ret = URC_OK; + + pr_debug("%s: insn = %08lx\n", __func__, insn); + + if ((insn & 0xc0) == 0x00) + ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4; + else if ((insn & 0xc0) == 0x40) { + ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4; + } else if ((insn & 0xf0) == 0x80) { + unsigned long mask; + + insn = (insn << 8) | unwind_get_byte(ctrl); + mask = insn & 0x0fff; + if (mask == 0) { + pr_warn("unwind: 'Refuse to unwind' instruction %04lx\n", + insn); + return -URC_FAILURE; + } + + ret = unwind_exec_pop_subset_r4_to_r13(ctrl, mask); + if (ret) + goto error; + } else if ((insn & 0xf0) == 0x90 && + (insn & 0x0d) != 0x0d) { + ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f]; + } else if ((insn & 0xf0) == 0xa0) { + ret = unwind_exec_pop_r4_to_rN(ctrl, insn); + if (ret) + goto error; + } else if (insn == 0xb0) { + if (ctrl->vrs[PC] == 0) + ctrl->vrs[PC] = ctrl->vrs[LR]; + /* no further processing */ + ctrl->entries = 0; + } else if (insn == 0xb1) { + unsigned long mask = unwind_get_byte(ctrl); + + if (mask == 0 || mask & 0xf0) { + pr_warn("unwind: Spare encoding %04lx\n", + (insn << 8) | mask); + return -URC_FAILURE; + } + + ret = unwind_exec_pop_subset_r0_to_r3(ctrl, mask); + if (ret) + goto error; + } else if (insn == 0xb2) { + unsigned long uleb128 = unwind_decode_uleb128(ctrl); + + ctrl->vrs[SP] += 0x204 + (uleb128 << 2); + } else { + pr_warn("unwind: Unhandled instruction %02lx\n", insn); + return -URC_FAILURE; + } + + pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__, + ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]); + +error: + return ret; +} + +/* + * Unwind a single frame starting with *sp for the symbol at *pc. It + * updates the *pc and *sp with the new values. + */ +int unwind_frame(struct stackframe *frame) +{ + const struct unwind_idx *idx; + struct unwind_ctrl_block ctrl; + unsigned long sp_low; + + /* store the highest address on the stack to avoid crossing it*/ + sp_low = frame->sp; + ctrl.sp_high = ALIGN(sp_low - THREAD_SIZE, THREAD_ALIGN) + + THREAD_SIZE; + + pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__, + frame->pc, frame->lr, frame->sp); + + idx = unwind_find_idx(frame->pc); + if (!idx) { + if (frame->pc && kernel_text_address(frame->pc)) { + if (in_module_plt(frame->pc) && frame->pc != frame->lr) { + /* + * Quoting Ard: Veneers only set PC using a + * PC+immediate LDR, and so they don't affect + * the state of the stack or the register file + */ + frame->pc = frame->lr; + return URC_OK; + } + pr_warn("unwind: Index not found %08lx\n", frame->pc); + } + return -URC_FAILURE; + } + + ctrl.vrs[FP] = frame->fp; + ctrl.vrs[SP] = frame->sp; + ctrl.vrs[LR] = frame->lr; + ctrl.vrs[PC] = 0; + + if (idx->insn == 1) + /* can't unwind */ + return -URC_FAILURE; + else if (frame->pc == prel31_to_addr(&idx->addr_offset)) { + /* + * Unwinding is tricky when we're halfway through the prologue, + * since the stack frame that the unwinder expects may not be + * fully set up yet. However, one thing we do know for sure is + * that if we are unwinding from the very first instruction of + * a function, we are still effectively in the stack frame of + * the caller, and the unwind info has no relevance yet. + */ + if (frame->pc == frame->lr) + return -URC_FAILURE; + frame->pc = frame->lr; + return URC_OK; + } else if ((idx->insn & 0x80000000) == 0) + /* prel31 to the unwind table */ + ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn); + else if ((idx->insn & 0xff000000) == 0x80000000) + /* only personality routine 0 supported in the index */ + ctrl.insn = &idx->insn; + else { + pr_warn("unwind: Unsupported personality routine %08lx in the index at %p\n", + idx->insn, idx); + return -URC_FAILURE; + } + + /* check the personality routine */ + if ((*ctrl.insn & 0xff000000) == 0x80000000) { + ctrl.byte = 2; + ctrl.entries = 1; + } else if ((*ctrl.insn & 0xff000000) == 0x81000000) { + ctrl.byte = 1; + ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16); + } else { + pr_warn("unwind: Unsupported personality routine %08lx at %p\n", + *ctrl.insn, ctrl.insn); + return -URC_FAILURE; + } + + ctrl.check_each_pop = 0; + + if (prel31_to_addr(&idx->addr_offset) == (u32)&call_with_stack) { + /* + * call_with_stack() is the only place where we permit SP to + * jump from one stack to another, and since we know it is + * guaranteed to happen, set up the SP bounds accordingly. + */ + sp_low = frame->fp; + ctrl.sp_high = ALIGN(frame->fp, THREAD_SIZE); + } + + while (ctrl.entries > 0) { + int urc; + if ((ctrl.sp_high - ctrl.vrs[SP]) < sizeof(ctrl.vrs)) + ctrl.check_each_pop = 1; + urc = unwind_exec_insn(&ctrl); + if (urc < 0) + return urc; + if (ctrl.vrs[SP] < sp_low || ctrl.vrs[SP] > ctrl.sp_high) + return -URC_FAILURE; + } + + if (ctrl.vrs[PC] == 0) + ctrl.vrs[PC] = ctrl.vrs[LR]; + + /* check for infinite loop */ + if (frame->pc == ctrl.vrs[PC] && frame->sp == ctrl.vrs[SP]) + return -URC_FAILURE; + + frame->fp = ctrl.vrs[FP]; + frame->sp = ctrl.vrs[SP]; + frame->lr = ctrl.vrs[LR]; + frame->pc = ctrl.vrs[PC]; + frame->lr_addr = ctrl.lr_addr; + + return URC_OK; +} + +void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk, + const char *loglvl) +{ + struct stackframe frame; + + pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); + + if (!tsk) + tsk = current; + + if (regs) { + arm_get_current_stackframe(regs, &frame); + /* PC might be corrupted, use LR in that case. */ + if (!kernel_text_address(regs->ARM_pc)) + frame.pc = regs->ARM_lr; + } else if (tsk == current) { + frame.fp = (unsigned long)__builtin_frame_address(0); + frame.sp = current_stack_pointer; + frame.lr = (unsigned long)__builtin_return_address(0); + /* We are saving the stack and execution state at this + * point, so we should ensure that frame.pc is within + * this block of code. + */ +here: + frame.pc = (unsigned long)&&here; + } else { + /* task blocked in __switch_to */ + frame.fp = thread_saved_fp(tsk); + frame.sp = thread_saved_sp(tsk); + /* + * The function calling __switch_to cannot be a leaf function + * so LR is recovered from the stack. + */ + frame.lr = 0; + frame.pc = thread_saved_pc(tsk); + } + + while (1) { + int urc; + unsigned long where = frame.pc; + + urc = unwind_frame(&frame); + if (urc < 0) + break; + dump_backtrace_entry(where, frame.pc, frame.sp - 4, loglvl); + } +} + +struct unwind_table *unwind_table_add(unsigned long start, unsigned long size, + unsigned long text_addr, + unsigned long text_size) +{ + unsigned long flags; + struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL); + + pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size, + text_addr, text_size); + + if (!tab) + return tab; + + tab->start = (const struct unwind_idx *)start; + tab->stop = (const struct unwind_idx *)(start + size); + tab->origin = unwind_find_origin(tab->start, tab->stop); + tab->begin_addr = text_addr; + tab->end_addr = text_addr + text_size; + + raw_spin_lock_irqsave(&unwind_lock, flags); + list_add_tail(&tab->list, &unwind_tables); + raw_spin_unlock_irqrestore(&unwind_lock, flags); + + return tab; +} + +void unwind_table_del(struct unwind_table *tab) +{ + unsigned long flags; + + if (!tab) + return; + + raw_spin_lock_irqsave(&unwind_lock, flags); + list_del(&tab->list); + raw_spin_unlock_irqrestore(&unwind_lock, flags); + + kfree(tab); +} -- cgit v1.2.3