arm64: stacktrace: track hyp stacks in unwinder's address space

Currently unwind_next_frame_record() has an optional callback to convert
the address space of the FP. This is necessary for the NVHE unwinder,
which tracks the stacks in the hyp VA space, but accesses the frame
records in the kernel VA space.

This is a bit unfortunate since it clutters unwind_next_frame_record(),
which will get in the way of future rework.

Instead, this patch changes the NVHE unwinder to track the stacks in the
kernel's VA space and translate to FP prior to calling
unwind_next_frame_record(). This removes the need for the translate_fp()
callback, as all unwinders consistently track stacks in the native
address space of the unwinder.

At the same time, this patch consolidates the generation of the stack
addresses behind the stackinfo_get_*() helpers.

Signed-off-by: Mark Rutland <[e-mail]>
Reviewed-by: Kalesh Singh <[e-mail]>
Reviewed-by: Madhavan T. Venkataraman <[e-mail]>
Reviewed-by: Mark Brown <[e-mail]>
Cc: Fuad Tabba <[e-mail]>
Cc: Marc Zyngier <[e-mail]>
Cc: Will Deacon <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Catalin Marinas <[e-mail]>

arch/arm64/include/asm/stacktrace/common.h

···
 	state->stack = stackinfo_get_unknown();
 }
 
-/**
- * typedef stack_trace_translate_fp_fn() - Translates a non-kernel frame
- * pointer to a kernel address.
- *
- * @fp:   the frame pointer to be updated to its kernel address.
- *
- * Return: true if the VA can be translated, false otherwise.
- *
- * Upon success @fp is updated to the corresponding kernel virtual address.
- */
-typedef bool (*stack_trace_translate_fp_fn)(unsigned long *fp);
-
 static struct stack_info *unwind_find_next_stack(const struct unwind_state *state,
 						 unsigned long sp,
 						 unsigned long size)
···
  * unwind_next_frame_record() - Unwind to the next frame record.
  *
  * @state:        the current unwind state.
- * @translate_fp: translates the fp prior to access (may be NULL)
  *
  * Return: 0 upon success, an error code otherwise.
  */
 static inline int
-unwind_next_frame_record(struct unwind_state *state,
-			 stack_trace_translate_fp_fn translate_fp)
+unwind_next_frame_record(struct unwind_state *state)
 {
-	unsigned long fp = state->fp, kern_fp = fp;
+	unsigned long fp = state->fp;
 	int err;
 
 	if (fp & 0x7)
···
 		return err;
 
 	/*
-	 * If fp is not from the current address space perform the necessary
-	 * translation before dereferencing it to get the next fp.
-	 */
-	if (translate_fp && !translate_fp(&kern_fp))
-		return -EINVAL;
-
-	/*
 	 * Record this frame record's values.
 	 */
-	state->fp = READ_ONCE(*(unsigned long *)(kern_fp));
-	state->pc = READ_ONCE(*(unsigned long *)(kern_fp + 8));
+	state->fp = READ_ONCE(*(unsigned long *)(fp));
+	state->pc = READ_ONCE(*(unsigned long *)(fp + 8));
 
 	return 0;
 }

arch/arm64/kernel/stacktrace.c

···
 	if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
 		return -ENOENT;
 
-	err = unwind_next_frame_record(state, NULL);
+	err = unwind_next_frame_record(state);
 	if (err)
 		return err;
 

arch/arm64/kvm/hyp/nvhe/stacktrace.c

···
 
 static int unwind_next(struct unwind_state *state)
 {
-	return unwind_next_frame_record(state, NULL);
+	return unwind_next_frame_record(state);
 }
 
 static void notrace unwind(struct unwind_state *state,

arch/arm64/kvm/stacktrace.c

···
 	};
 }
 
+static struct stack_info stackinfo_get_overflow_kern_va(void)
+{
+	unsigned long low = (unsigned long)this_cpu_ptr_nvhe_sym(overflow_stack);
+	unsigned long high = low + OVERFLOW_STACK_SIZE;
+
+	return (struct stack_info) {
+		.low = low,
+		.high = high,
+	};
+}
+
 static struct stack_info stackinfo_get_hyp(void)
 {
 	struct kvm_nvhe_stacktrace_info *stacktrace_info
 				= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
 	unsigned long low = (unsigned long)stacktrace_info->stack_base;
+	unsigned long high = low + PAGE_SIZE;
+
+	return (struct stack_info) {
+		.low = low,
+		.high = high,
+	};
+}
+
+static struct stack_info stackinfo_get_hyp_kern_va(void)
+{
+	unsigned long low = (unsigned long)*this_cpu_ptr(&kvm_arm_hyp_stack_page);
 	unsigned long high = low + PAGE_SIZE;
 
 	return (struct stack_info) {
···
  */
 static bool kvm_nvhe_stack_kern_va(unsigned long *addr, unsigned long size)
 {
-	struct kvm_nvhe_stacktrace_info *stacktrace_info;
-	unsigned long hyp_base, kern_base, hyp_offset;
-	struct stack_info stack;
+	struct stack_info stack_hyp, stack_kern;
 
-	stacktrace_info = this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
-
-	stack = stackinfo_get_hyp();
-	if (stackinfo_on_stack(&stack, *addr, size)) {
-		kern_base = (unsigned long)*this_cpu_ptr(&kvm_arm_hyp_stack_page);
-		hyp_base = (unsigned long)stacktrace_info->stack_base;
+	stack_hyp = stackinfo_get_hyp();
+	stack_kern = stackinfo_get_hyp_kern_va();
+	if (stackinfo_on_stack(&stack_hyp, *addr, size))
 		goto found;
-	}
 
-	stack = stackinfo_get_overflow();
-	if (stackinfo_on_stack(&stack, *addr, size)) {
-		kern_base = (unsigned long)this_cpu_ptr_nvhe_sym(overflow_stack);
-		hyp_base = (unsigned long)stacktrace_info->overflow_stack_base;
+	stack_hyp = stackinfo_get_overflow();
+	stack_kern = stackinfo_get_overflow_kern_va();
+	if (stackinfo_on_stack(&stack_hyp, *addr, size))
 		goto found;
-	}
 
 	return false;
 
 found:
-	hyp_offset = *addr - hyp_base;
-
-	*addr = kern_base + hyp_offset;
-
+	*addr = *addr - stack_hyp.low + stack_kern.low;
 	return true;
 }
 
···
 
 static int unwind_next(struct unwind_state *state)
 {
-	return unwind_next_frame_record(state, kvm_nvhe_stack_kern_record_va);
+	/*
+	 * The FP is in the hypervisor VA space. Convert it to the kernel VA
+	 * space so it can be unwound by the regular unwind functions.
+	 */
+	if (!kvm_nvhe_stack_kern_record_va(&state->fp))
+		return -EINVAL;
+
+	return unwind_next_frame_record(state);
 }
 
 static void unwind(struct unwind_state *state,
···
 {
 	struct kvm_nvhe_stacktrace_info *stacktrace_info;
 	struct stack_info stacks[] = {
-		stackinfo_get_overflow(),
-		stackinfo_get_hyp(),
+		stackinfo_get_overflow_kern_va(),
+		stackinfo_get_hyp_kern_va(),
 	};
 	struct unwind_state state = {
 		.stacks = stacks,