summaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/unwind.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--arch/arm/kernel/unwind.c562
1 files changed, 562 insertions, 0 deletions
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
new file mode 100644
index 000000000..7e90f17a0
--- /dev/null
+++ b/arch/arm/kernel/unwind.c
@@ -0,0 +1,562 @@
+// 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.
+#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2) && !defined(__clang__)
+#warning Your compiler is too buggy; it is known to not compile ARM unwind support.
+#warning Change compiler or disable ARM_UNWIND option.
+#endif
+#endif /* __CHECKER__ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+
+#include <asm/stacktrace.h>
+#include <asm/traps.h>
+#include <asm/unwind.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 */
+ /*
+ * 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;
+
+ ctrl->vrs[reg] = *(*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)
+{
+ unsigned long low;
+ const struct unwind_idx *idx;
+ struct unwind_ctrl_block ctrl;
+
+ /* store the highest address on the stack to avoid crossing it*/
+ low = frame->sp;
+ ctrl.sp_high = ALIGN(low, THREAD_SIZE);
+
+ pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
+ frame->pc, frame->lr, frame->sp);
+
+ if (!kernel_text_address(frame->pc))
+ return -URC_FAILURE;
+
+ idx = unwind_find_idx(frame->pc);
+ if (!idx) {
+ 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 ((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;
+
+ 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] < 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];
+
+ 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);
+ frame.pc = (unsigned long)unwind_backtrace;
+ } 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);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-16 18:38:34 +0000