// SPDX-License-Identifier: BSD-2-Clause
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/*
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* Copyright (c) 2019 Fuzhou Rockchip Electronics Co., Ltd
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*
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* This file is taken and modified from the OP-TEE project.
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*/
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#include <common.h>
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#include <stacktrace.h>
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#include <asm/sections.h>
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DECLARE_GLOBAL_DATA_PTR;
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/* The register names */
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#define FP 11
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#define SP 13
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#define LR 14
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#define PC 15
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/*
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* Definitions for the instruction interpreter.
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*
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* The ARM EABI specifies how to perform the frame unwinding in the
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* Exception Handling ABI for the ARM Architecture document. To perform
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* the unwind we need to know the initial frame pointer, stack pointer,
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* link register and program counter. We then find the entry within the
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* index table that points to the function the program counter is within.
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* This gives us either a list of three instructions to process, a 31-bit
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* relative offset to a table of instructions, or a value telling us
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* we can't unwind any further.
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*
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* When we have the instructions to process we need to decode them
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* following table 4 in section 9.3. This describes a collection of bit
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* patterns to encode that steps to take to update the stack pointer and
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* link register to the correct values at the start of the function.
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*/
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/* A special case when we are unable to unwind past this function */
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#define EXIDX_CANTUNWIND 1
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/*
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* Entry types.
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* These are the only entry types that have been seen in the kernel.
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*/
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#define ENTRY_MASK 0xff000000
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#define ENTRY_ARM_SU16 0x80000000
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#define ENTRY_ARM_LU16 0x81000000
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/* Instruction masks. */
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#define INSN_VSP_MASK 0xc0
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#define INSN_VSP_SIZE_MASK 0x3f
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#define INSN_STD_MASK 0xf0
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#define INSN_STD_DATA_MASK 0x0f
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#define INSN_POP_TYPE_MASK 0x08
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#define INSN_POP_COUNT_MASK 0x07
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#define INSN_VSP_LARGE_INC_MASK 0xff
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/* Instruction definitions */
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#define INSN_VSP_INC 0x00
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#define INSN_VSP_DEC 0x40
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#define INSN_POP_MASKED 0x80
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#define INSN_VSP_REG 0x90
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#define INSN_POP_COUNT 0xa0
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#define INSN_FINISH 0xb0
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#define INSN_POP_REGS 0xb1
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#define INSN_VSP_LARGE_INC 0xb2
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#define SHIFT_U32(v, shift) ((uint32_t)(v) << (shift))
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/* The state of the unwind process (32-bit mode) */
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struct unwind_state_arm32 {
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uint32_t registers[16];
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uint32_t start_pc;
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ulong insn;
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unsigned int entries;
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unsigned int byte;
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uint16_t update_mask;
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};
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/* An item in the exception index table */
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struct unwind_idx {
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uint32_t offset;
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uint32_t insn;
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};
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static __always_inline uint32_t read_pc(void)
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{
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uint32_t val;
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asm volatile ("adr %0, ." : "=r" (val));
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return val;
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}
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static __always_inline uint32_t read_sp(void)
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{
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uint32_t val;
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asm volatile ("mov %0, sp" : "=r" (val));
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return val;
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}
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static __always_inline uint32_t read_lr(void)
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{
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uint32_t val;
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asm volatile ("mov %0, lr" : "=r" (val));
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return val;
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}
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static __always_inline uint32_t read_fp(void)
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{
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uint32_t val;
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asm volatile ("mov %0, fp" : "=r" (val));
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return val;
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}
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static __always_inline uint32_t read_r7(void)
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{
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uint32_t val;
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asm volatile ("mov %0, r7" : "=r" (val));
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return val;
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}
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static bool copy_in(void *dst, const void *src, size_t n, bool kernel_data)
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{
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if (!kernel_data)
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return false;
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memcpy(dst, src, n);
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return true;
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}
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/* Expand a 31-bit signed value to a 32-bit signed value */
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static int32_t expand_prel31(uint32_t prel31)
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{
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return prel31 | SHIFT_U32(prel31 & BIT(30), 1);
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}
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/*
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* Perform a binary search of the index table to find the function
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* with the largest address that doesn't exceed addr.
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*/
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static struct unwind_idx *find_index(uint32_t addr, ulong exidx,
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size_t exidx_sz)
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{
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ulong idx_start, idx_end;
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unsigned int min, mid, max;
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struct unwind_idx *start;
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struct unwind_idx *item;
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int32_t prel31_addr;
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ulong func_addr;
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start = (struct unwind_idx *)exidx;
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idx_start = exidx;
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idx_end = exidx + exidx_sz;
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min = 0;
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max = (idx_end - idx_start) / sizeof(struct unwind_idx);
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while (min != max) {
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mid = min + (max - min + 1) / 2;
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item = &start[mid];
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prel31_addr = expand_prel31(item->offset);
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func_addr = (ulong)&item->offset + prel31_addr;
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if (func_addr <= addr) {
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min = mid;
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} else {
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max = mid - 1;
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}
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}
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return &start[min];
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}
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/* Reads the next byte from the instruction list */
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static bool unwind_exec_read_byte(struct unwind_state_arm32 *state,
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uint32_t *ret_insn, bool kernel_stack)
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{
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uint32_t insn;
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if (!copy_in(&insn, (void *)state->insn, sizeof(insn), kernel_stack))
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return false;
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/* Read the unwind instruction */
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*ret_insn = (insn >> (state->byte * 8)) & 0xff;
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/* Update the location of the next instruction */
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if (state->byte == 0) {
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state->byte = 3;
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state->insn += sizeof(uint32_t);
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state->entries--;
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} else {
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state->byte--;
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}
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return true;
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}
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static bool pop_vsp(uint32_t *reg, ulong *vsp, bool kernel_stack,
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ulong stack, size_t stack_size)
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{
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if (*vsp > gd->start_addr_sp ||
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*vsp < gd->start_addr_sp - CONFIG_SYS_STACK_SIZE)
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return false;
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if (!copy_in(reg, (void *)*vsp, sizeof(*reg), kernel_stack))
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return false;
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(*vsp) += sizeof(*reg);
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return true;
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}
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/* Executes the next instruction on the list */
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static bool unwind_exec_insn(struct unwind_state_arm32 *state,
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bool kernel_stack, ulong stack,
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size_t stack_size)
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{
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uint32_t insn;
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ulong vsp = state->registers[SP];
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int update_vsp = 0;
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/* Read the next instruction */
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if (!unwind_exec_read_byte(state, &insn, kernel_stack))
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return false;
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if ((insn & INSN_VSP_MASK) == INSN_VSP_INC) {
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state->registers[SP] += ((insn & INSN_VSP_SIZE_MASK) << 2) + 4;
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} else if ((insn & INSN_VSP_MASK) == INSN_VSP_DEC) {
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state->registers[SP] -= ((insn & INSN_VSP_SIZE_MASK) << 2) + 4;
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} else if ((insn & INSN_STD_MASK) == INSN_POP_MASKED) {
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uint32_t mask;
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unsigned int reg;
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/* Load the mask */
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if (!unwind_exec_read_byte(state, &mask, kernel_stack))
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return false;
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mask |= (insn & INSN_STD_DATA_MASK) << 8;
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/* We have a refuse to unwind instruction */
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if (mask == 0)
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return false;
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/* Update SP */
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update_vsp = 1;
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/* Load the registers */
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for (reg = 4; mask && reg < 16; mask >>= 1, reg++) {
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if (mask & 1) {
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if (!pop_vsp(&state->registers[reg], &vsp,
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kernel_stack, stack, stack_size))
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return false;
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state->update_mask |= 1 << reg;
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/* If we have updated SP kep its value */
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if (reg == SP)
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update_vsp = 0;
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}
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}
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} else if ((insn & INSN_STD_MASK) == INSN_VSP_REG &&
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((insn & INSN_STD_DATA_MASK) != 13) &&
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((insn & INSN_STD_DATA_MASK) != 15)) {
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/* sp = register */
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state->registers[SP] =
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state->registers[insn & INSN_STD_DATA_MASK];
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} else if ((insn & INSN_STD_MASK) == INSN_POP_COUNT) {
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unsigned int count, reg;
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/* Read how many registers to load */
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count = insn & INSN_POP_COUNT_MASK;
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/* Update sp */
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update_vsp = 1;
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/* Pop the registers */
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for (reg = 4; reg <= 4 + count; reg++) {
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if (!pop_vsp(&state->registers[reg], &vsp,
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kernel_stack, stack, stack_size))
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return false;
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state->update_mask |= 1 << reg;
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}
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/* Check if we are in the pop r14 version */
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if ((insn & INSN_POP_TYPE_MASK) != 0) {
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if (!pop_vsp(&state->registers[14], &vsp, kernel_stack,
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stack, stack_size))
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return false;
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}
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} else if (insn == INSN_FINISH) {
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/* Stop processing */
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state->entries = 0;
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} else if (insn == INSN_POP_REGS) {
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uint32_t mask;
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unsigned int reg;
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if (!unwind_exec_read_byte(state, &mask, kernel_stack))
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return false;
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if (mask == 0 || (mask & 0xf0) != 0)
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return false;
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/* Update SP */
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update_vsp = 1;
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/* Load the registers */
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for (reg = 0; mask && reg < 4; mask >>= 1, reg++) {
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if (mask & 1) {
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if (!pop_vsp(&state->registers[reg], &vsp,
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kernel_stack, stack, stack_size))
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return false;
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state->update_mask |= 1 << reg;
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}
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}
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} else if ((insn & INSN_VSP_LARGE_INC_MASK) == INSN_VSP_LARGE_INC) {
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uint32_t uleb128;
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/* Read the increment value */
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if (!unwind_exec_read_byte(state, &uleb128, kernel_stack))
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return false;
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state->registers[SP] += 0x204 + (uleb128 << 2);
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} else {
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/* We hit a new instruction that needs to be implemented */
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printf("Unhandled instruction %.2x\n", insn);
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return false;
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}
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if (update_vsp)
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state->registers[SP] = vsp;
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return true;
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}
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/* Performs the unwind of a function */
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static bool unwind_tab(struct unwind_state_arm32 *state, bool kernel_stack,
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ulong stack, size_t stack_size)
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{
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uint32_t entry;
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uint32_t insn;
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/* Set PC to a known value */
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state->registers[PC] = 0;
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if (!copy_in(&insn, (void *)state->insn, sizeof(insn), kernel_stack)) {
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printf("Bad insn addr %p", (void *)state->insn);
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return true;
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}
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/* Read the personality */
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entry = insn & ENTRY_MASK;
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if (entry == ENTRY_ARM_SU16) {
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state->byte = 2;
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state->entries = 1;
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} else if (entry == ENTRY_ARM_LU16) {
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state->byte = 1;
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state->entries = ((insn >> 16) & 0xFF) + 1;
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} else {
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printf("Unknown entry: %x\n", entry);
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return true;
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}
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while (state->entries > 0) {
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if (!unwind_exec_insn(state, kernel_stack, stack, stack_size))
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return true;
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}
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/*
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* The program counter was not updated, load it from the link register.
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*/
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if (state->registers[PC] == 0) {
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state->registers[PC] = state->registers[LR];
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/*
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* If the program counter changed, flag it in the update mask.
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*/
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if (state->start_pc != state->registers[PC])
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state->update_mask |= 1 << PC;
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/* Check again */
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if (state->registers[PC] == 0)
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return true;
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}
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return false;
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}
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bool unwind_stack_arm32(struct unwind_state_arm32 *state, ulong exidx,
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size_t exidx_sz, bool kernel_stack, ulong stack,
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size_t stack_size)
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{
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struct unwind_idx *index;
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bool finished;
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if (!exidx_sz)
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return false;
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/* Reset the mask of updated registers */
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state->update_mask = 0;
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/* The pc value is correct and will be overwritten, save it */
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state->start_pc = state->registers[PC];
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/* Find the item to run */
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index = find_index(state->start_pc, exidx, exidx_sz);
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finished = false;
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if (index->insn != EXIDX_CANTUNWIND) {
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if (index->insn & (1U << 31)) {
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/* The data is within the instruction */
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state->insn = (ulong)&index->insn;
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} else {
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/* A prel31 offset to the unwind table */
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state->insn = (ulong)&index->insn +
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expand_prel31(index->insn);
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}
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/* Run the unwind function */
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finished = unwind_tab(state, kernel_stack, stack, stack_size);
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}
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/* This is the top of the stack, finish */
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if (index->insn == EXIDX_CANTUNWIND)
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finished = true;
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return !finished;
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}
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static uint32_t offset_prel31(uint32_t addr, int32_t offset)
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{
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return (addr + offset) & 0x7FFFFFFFUL;
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}
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int relocate_exidx(void *exidx, size_t exidx_sz, int32_t offset)
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{
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size_t num_items = exidx_sz / sizeof(struct unwind_idx);
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struct unwind_idx *start = (struct unwind_idx *)exidx;
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size_t n;
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for (n = 0; n < num_items; n++) {
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struct unwind_idx *item = &start[n];
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if (item->offset & BIT(31))
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return -EINVAL;
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/* Offset to the start of the function has to be adjusted */
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item->offset = offset_prel31(item->offset, offset);
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if (item->insn == EXIDX_CANTUNWIND)
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continue;
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if (item->insn & BIT(31)) {
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/* insn is a table entry itself */
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continue;
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}
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/*
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* insn is an offset to an entry in .ARM.extab so it has to be
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* adjusted
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*/
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item->insn = offset_prel31(item->insn, offset);
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}
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return 0;
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}
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void print_stack_arm32(struct unwind_state_arm32 *state,
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ulong exidx, size_t exidx_sz, bool kernel_stack,
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ulong stack, size_t stack_size)
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{
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ulong pc, lr;
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#if defined(CONFIG_TPL_BUILD)
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char *build = "tpl";
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#elif defined(CONFIG_SPL_BUILD)
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char *build = "spl";
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#else
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char *build = "";
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#endif
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if (gd->flags & GD_FLG_RELOC) {
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pc = (ulong)state->registers[PC] - gd->reloc_off;
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lr = (ulong)state->registers[LR] - gd->reloc_off;
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} else {
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pc = (ulong)state->registers[PC];
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lr = (ulong)state->registers[LR];
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}
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printf("\nCall trace:\n");
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printf(" PC: [< %08lx >]\n", pc);
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printf(" LR: [< %08lx >]\n", lr);
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printf("\nStack:\n");
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do {
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if (gd->flags & GD_FLG_RELOC)
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pc = (ulong)state->registers[PC] - gd->reloc_off;
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else
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pc = (ulong)state->registers[PC];
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printf(" [< %08lx >]\n", pc);
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} while (unwind_stack_arm32(state, exidx, exidx_sz,
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kernel_stack, stack, stack_size));
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printf("\nCopy info from \"Call trace...\" to a file(eg. dump.txt), and run\n"
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"command in your U-Boot project: "
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"./scripts/stacktrace.sh dump.txt %s\n\n", build);
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}
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void dump_core_stack(struct pt_regs *regs)
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{
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struct unwind_state_arm32 state;
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ulong exidx = (ulong)__exidx_start;
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size_t exidx_sz = (ulong)__exidx_end - (ulong)__exidx_start;
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ulong stack = gd->start_addr_sp;
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size_t stack_size = CONFIG_SYS_STACK_SIZE;
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int i;
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/* Don't use memset(), which updates LR ! */
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for (i = 0; i < 16; i++)
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state.registers[i] = 0;
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state.update_mask = 0;
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state.start_pc = 0;
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state.entries = 0;
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state.insn = 0;
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state.byte = 0;
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/* r7: Thumb-style frame pointer */
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state.registers[7] = regs->ARM_r7;
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/* r11: ARM-style frame pointer */
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state.registers[FP] = regs->ARM_ip;
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state.registers[SP] = regs->ARM_sp;
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state.registers[LR] = regs->ARM_lr;
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state.registers[PC] = regs->ARM_pc;
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print_stack_arm32(&state, exidx, exidx_sz,
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true, stack, stack_size);
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}
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void dump_stack(void)
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{
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struct pt_regs regs;
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regs.ARM_r7 = read_r7();
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regs.ARM_ip = read_fp();
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regs.ARM_sp = read_sp();
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regs.ARM_lr = read_lr();
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regs.ARM_pc = (uint32_t)dump_stack;
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dump_core_stack(®s);
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}
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