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-rw-r--r--arch/loongarch/kernel/unwind_prologue.c187
1 files changed, 187 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
new file mode 100644
index 000000000..1c5b65756
--- /dev/null
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#include <linux/kallsyms.h>
+
+#include <asm/inst.h>
+#include <asm/ptrace.h>
+#include <asm/unwind.h>
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+
+ if (unwind_done(state))
+ return 0;
+ else if (state->type)
+ return state->pc;
+ else if (state->first)
+ return state->pc;
+
+ return *(unsigned long *)(state->sp);
+
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+static bool unwind_by_guess(struct unwind_state *state)
+{
+ struct stack_info *info = &state->stack_info;
+ unsigned long addr;
+
+ for (state->sp += sizeof(unsigned long);
+ state->sp < info->end;
+ state->sp += sizeof(unsigned long)) {
+ addr = *(unsigned long *)(state->sp);
+ if (__kernel_text_address(addr))
+ return true;
+ }
+
+ return false;
+}
+
+static bool unwind_by_prologue(struct unwind_state *state)
+{
+ struct stack_info *info = &state->stack_info;
+ union loongarch_instruction *ip, *ip_end;
+ long frame_ra = -1;
+ unsigned long frame_size = 0;
+ unsigned long size, offset, pc = state->pc;
+
+ if (state->sp >= info->end || state->sp < info->begin)
+ return false;
+
+ if (!kallsyms_lookup_size_offset(pc, &size, &offset))
+ return false;
+
+ ip = (union loongarch_instruction *)(pc - offset);
+ ip_end = (union loongarch_instruction *)pc;
+
+ while (ip < ip_end) {
+ if (is_stack_alloc_ins(ip)) {
+ frame_size = (1 << 12) - ip->reg2i12_format.immediate;
+ ip++;
+ break;
+ }
+ ip++;
+ }
+
+ if (!frame_size) {
+ if (state->first)
+ goto first;
+
+ return false;
+ }
+
+ while (ip < ip_end) {
+ if (is_ra_save_ins(ip)) {
+ frame_ra = ip->reg2i12_format.immediate;
+ break;
+ }
+ if (is_branch_ins(ip))
+ break;
+ ip++;
+ }
+
+ if (frame_ra < 0) {
+ if (state->first) {
+ state->sp = state->sp + frame_size;
+ goto first;
+ }
+ return false;
+ }
+
+ if (state->first)
+ state->first = false;
+
+ state->pc = *(unsigned long *)(state->sp + frame_ra);
+ state->sp = state->sp + frame_size;
+ return !!__kernel_text_address(state->pc);
+
+first:
+ state->first = false;
+ if (state->pc == state->ra)
+ return false;
+
+ state->pc = state->ra;
+
+ return !!__kernel_text_address(state->ra);
+}
+
+void unwind_start(struct unwind_state *state, struct task_struct *task,
+ struct pt_regs *regs)
+{
+ memset(state, 0, sizeof(*state));
+ state->type = UNWINDER_PROLOGUE;
+
+ if (regs) {
+ state->sp = regs->regs[3];
+ state->pc = regs->csr_era;
+ state->ra = regs->regs[1];
+ if (!__kernel_text_address(state->pc))
+ state->type = UNWINDER_GUESS;
+ } else if (task && task != current) {
+ state->sp = thread_saved_fp(task);
+ state->pc = thread_saved_ra(task);
+ state->ra = 0;
+ } else {
+ state->sp = (unsigned long)__builtin_frame_address(0);
+ state->pc = (unsigned long)__builtin_return_address(0);
+ state->ra = 0;
+ }
+
+ state->task = task;
+ state->first = true;
+
+ get_stack_info(state->sp, state->task, &state->stack_info);
+
+ if (!unwind_done(state) && !__kernel_text_address(state->pc))
+ unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(unwind_start);
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+ struct stack_info *info = &state->stack_info;
+ struct pt_regs *regs;
+ unsigned long pc;
+
+ if (unwind_done(state))
+ return false;
+
+ do {
+ switch (state->type) {
+ case UNWINDER_GUESS:
+ state->first = false;
+ if (unwind_by_guess(state))
+ return true;
+ break;
+
+ case UNWINDER_PROLOGUE:
+ if (unwind_by_prologue(state))
+ return true;
+
+ if (info->type == STACK_TYPE_IRQ &&
+ info->end == state->sp) {
+ regs = (struct pt_regs *)info->next_sp;
+ pc = regs->csr_era;
+
+ if (user_mode(regs) || !__kernel_text_address(pc))
+ return false;
+
+ state->pc = pc;
+ state->sp = regs->regs[3];
+ state->ra = regs->regs[1];
+ state->first = true;
+ get_stack_info(state->sp, state->task, info);
+
+ return true;
+ }
+ }
+
+ state->sp = info->next_sp;
+
+ } while (!get_stack_info(state->sp, state->task, info));
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);