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-rw-r--r--arch/loongarch/kernel/unwind_prologue.c265
1 files changed, 265 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
new file mode 100644
index 0000000000..929ae24028
--- /dev/null
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#include <linux/cpumask.h>
+#include <linux/ftrace.h>
+#include <linux/kallsyms.h>
+
+#include <asm/inst.h>
+#include <asm/loongson.h>
+#include <asm/ptrace.h>
+#include <asm/setup.h>
+#include <asm/unwind.h>
+
+extern const int unwind_hint_ade;
+extern const int unwind_hint_ale;
+extern const int unwind_hint_bp;
+extern const int unwind_hint_fpe;
+extern const int unwind_hint_fpu;
+extern const int unwind_hint_lsx;
+extern const int unwind_hint_lasx;
+extern const int unwind_hint_lbt;
+extern const int unwind_hint_ri;
+extern const int unwind_hint_watch;
+extern unsigned long eentry;
+#ifdef CONFIG_NUMA
+extern unsigned long pcpu_handlers[NR_CPUS];
+#endif
+
+static inline bool scan_handlers(unsigned long entry_offset)
+{
+ int idx, offset;
+
+ if (entry_offset >= EXCCODE_INT_START * VECSIZE)
+ return false;
+
+ idx = entry_offset / VECSIZE;
+ offset = entry_offset % VECSIZE;
+ switch (idx) {
+ case EXCCODE_ADE:
+ return offset == unwind_hint_ade;
+ case EXCCODE_ALE:
+ return offset == unwind_hint_ale;
+ case EXCCODE_BP:
+ return offset == unwind_hint_bp;
+ case EXCCODE_FPE:
+ return offset == unwind_hint_fpe;
+ case EXCCODE_FPDIS:
+ return offset == unwind_hint_fpu;
+ case EXCCODE_LSXDIS:
+ return offset == unwind_hint_lsx;
+ case EXCCODE_LASXDIS:
+ return offset == unwind_hint_lasx;
+ case EXCCODE_BTDIS:
+ return offset == unwind_hint_lbt;
+ case EXCCODE_INE:
+ return offset == unwind_hint_ri;
+ case EXCCODE_WATCH:
+ return offset == unwind_hint_watch;
+ default:
+ return false;
+ }
+}
+
+static inline bool fix_exception(unsigned long pc)
+{
+#ifdef CONFIG_NUMA
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ if (!pcpu_handlers[cpu])
+ continue;
+ if (scan_handlers(pc - pcpu_handlers[cpu]))
+ return true;
+ }
+#endif
+ return scan_handlers(pc - eentry);
+}
+
+/*
+ * As we meet ftrace_regs_entry, reset first flag like first doing
+ * tracing. Prologue analysis will stop soon because PC is at entry.
+ */
+static inline bool fix_ftrace(unsigned long pc)
+{
+#ifdef CONFIG_DYNAMIC_FTRACE
+ return pc == (unsigned long)ftrace_call + LOONGARCH_INSN_SIZE;
+#else
+ return false;
+#endif
+}
+
+static inline bool unwind_state_fixup(struct unwind_state *state)
+{
+ if (!fix_exception(state->pc) && !fix_ftrace(state->pc))
+ return false;
+
+ state->reset = true;
+ return true;
+}
+
+/*
+ * LoongArch function prologue is like follows,
+ * [instructions not use stack var]
+ * addi.d sp, sp, -imm
+ * st.d xx, sp, offset <- save callee saved regs and
+ * st.d yy, sp, offset save ra if function is nest.
+ * [others instructions]
+ */
+static bool unwind_by_prologue(struct unwind_state *state)
+{
+ long frame_ra = -1;
+ unsigned long frame_size = 0;
+ unsigned long size, offset, pc;
+ struct pt_regs *regs;
+ struct stack_info *info = &state->stack_info;
+ union loongarch_instruction *ip, *ip_end;
+
+ if (state->sp >= info->end || state->sp < info->begin)
+ return false;
+
+ if (state->reset) {
+ regs = (struct pt_regs *)state->sp;
+ state->first = true;
+ state->reset = false;
+ state->pc = regs->csr_era;
+ state->ra = regs->regs[1];
+ state->sp = regs->regs[3];
+ return true;
+ }
+
+ /*
+ * When first is not set, the PC is a return address in the previous frame.
+ * We need to adjust its value in case overflow to the next symbol.
+ */
+ pc = state->pc - (state->first ? 0 : LOONGARCH_INSN_SIZE);
+ 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++;
+ }
+
+ /*
+ * Can't find stack alloc action, PC may be in a leaf function. Only the
+ * first being true is reasonable, otherwise indicate analysis is broken.
+ */
+ 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++;
+ }
+
+ /* Can't find save $ra action, PC may be in a leaf function, too. */
+ if (frame_ra < 0) {
+ if (state->first) {
+ state->sp = state->sp + frame_size;
+ goto first;
+ }
+ return false;
+ }
+
+ state->pc = *(unsigned long *)(state->sp + frame_ra);
+ state->sp = state->sp + frame_size;
+ goto out;
+
+first:
+ state->pc = state->ra;
+
+out:
+ state->first = false;
+ return unwind_state_fixup(state) || __kernel_text_address(state->pc);
+}
+
+static bool next_frame(struct unwind_state *state)
+{
+ unsigned long pc;
+ struct pt_regs *regs;
+ struct stack_info *info = &state->stack_info;
+
+ if (unwind_done(state))
+ return false;
+
+ do {
+ if (unwind_by_prologue(state)) {
+ state->pc = unwind_graph_addr(state, state->pc, state->sp);
+ 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))
+ goto out;
+
+ state->first = true;
+ state->pc = pc;
+ state->ra = regs->regs[1];
+ state->sp = regs->regs[3];
+ get_stack_info(state->sp, state->task, info);
+
+ return true;
+ }
+
+ state->sp = info->next_sp;
+
+ } while (!get_stack_info(state->sp, state->task, info));
+
+out:
+ state->stack_info.type = STACK_TYPE_UNKNOWN;
+ return false;
+}
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+ return __unwind_get_return_address(state);
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+void unwind_start(struct unwind_state *state, struct task_struct *task,
+ struct pt_regs *regs)
+{
+ __unwind_start(state, task, regs);
+ state->type = UNWINDER_PROLOGUE;
+ state->first = true;
+
+ /*
+ * The current PC is not kernel text address, we cannot find its
+ * relative symbol. Thus, prologue analysis will be broken. Luckily,
+ * we can use the default_next_frame().
+ */
+ if (!__kernel_text_address(state->pc)) {
+ state->type = UNWINDER_GUESS;
+ if (!unwind_done(state))
+ unwind_next_frame(state);
+ }
+}
+EXPORT_SYMBOL_GPL(unwind_start);
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+ return state->type == UNWINDER_PROLOGUE ?
+ next_frame(state) : default_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 13:53:25 +0000