KVM: arm64: Make unwind()/on_accessible_stack() per-unwinder functions

Having multiple versions of on_accessible_stack() (one per unwinder)
makes it very hard to reason about what is used where due to the
complexity of the various includes, the forward declarations, and
the reliance on everything being 'inline'.

Instead, move the code back where it should be. Each unwinder
implements:

- on_accessible_stack() as well as the helpers it depends on,

- unwind()/unwind_next(), as they pass on_accessible_stack as
  a parameter to unwind_next_common() (which is the only common
  code here)

This hardly results in any duplication, and makes it much
easier to reason about the code.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20220727142906.1856759-4-maz@kernel.org

1 files changed, 55 insertions, 0 deletions

diff --git a/arch/arm64/kvm/stacktrace.c b/arch/arm64/kvm/stacktrace.c
index 9812aefdcfb4..4d5fec3175ff 100644
--- a/arch/arm64/kvm/stacktrace.c
+++ b/arch/arm64/kvm/stacktrace.c
@@ -21,6 +21,61 @@
 
 #include <asm/stacktrace/nvhe.h>
 
+static bool on_overflow_stack(unsigned long sp, unsigned long size,
+			      struct stack_info *info)
+{
+	struct kvm_nvhe_stacktrace_info *stacktrace_info
+				= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
+	unsigned long low = (unsigned long)stacktrace_info->overflow_stack_base;
+	unsigned long high = low + OVERFLOW_STACK_SIZE;
+
+	return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);
+}
+
+static bool on_hyp_stack(unsigned long sp, unsigned long size,
+			 struct stack_info *info)
+{
+	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 on_stack(sp, size, low, high, STACK_TYPE_HYP, info);
+}
+
+static bool on_accessible_stack(const struct task_struct *tsk,
+				unsigned long sp, unsigned long size,
+				struct stack_info *info)
+{
+	if (info)
+		info->type = STACK_TYPE_UNKNOWN;
+
+	return (on_overflow_stack(sp, size, info) ||
+		on_hyp_stack(sp, size, info));
+}
+
+static int unwind_next(struct unwind_state *state)
+{
+	struct stack_info info;
+
+	return unwind_next_common(state, &info, on_accessible_stack,
+				  kvm_nvhe_stack_kern_va);
+}
+
+static void unwind(struct unwind_state *state,
+		   stack_trace_consume_fn consume_entry, void *cookie)
+{
+	while (1) {
+		int ret;
+
+		if (!consume_entry(cookie, state->pc))
+			break;
+		ret = unwind_next(state);
+		if (ret < 0)
+			break;
+	}
+}
+
 /*
  * kvm_nvhe_dump_backtrace_entry - Symbolize and print an nVHE backtrace entry
  *