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

2 files changed, 16 insertions, 123 deletions

diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h
index 3ebb69ea374a..18046a7248a2 100644
--- a/arch/arm64/include/asm/stacktrace/common.h
+++ b/arch/arm64/include/asm/stacktrace/common.h
@@ -79,15 +79,6 @@ struct unwind_state {
 	struct task_struct *task;
 };
 
-static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
-				     struct stack_info *info);
-
-static inline bool on_accessible_stack(const struct task_struct *tsk,
-				       unsigned long sp, unsigned long size,
-				       struct stack_info *info);
-
-static inline int unwind_next(struct unwind_state *state);
-
 static inline bool on_stack(unsigned long sp, unsigned long size,
 			    unsigned long low, unsigned long high,
 			    enum stack_type type, struct stack_info *info)
@@ -106,21 +97,6 @@ static inline bool on_stack(unsigned long sp, unsigned long size,
 	return true;
 }
 
-static inline bool on_accessible_stack_common(const struct task_struct *tsk,
-					      unsigned long sp,
-					      unsigned long size,
-					      struct stack_info *info)
-{
-	if (info)
-		info->type = STACK_TYPE_UNKNOWN;
-
-	/*
-	 * Both the kernel and nvhe hypervisor make use of
-	 * an overflow_stack
-	 */
-	return on_overflow_stack(sp, size, info);
-}
-
 static inline void unwind_init_common(struct unwind_state *state,
 				      struct task_struct *task)
 {
@@ -156,8 +132,22 @@ static inline void unwind_init_common(struct unwind_state *state,
 typedef bool (*stack_trace_translate_fp_fn)(unsigned long *fp,
 					    enum stack_type type);
 
+/*
+ * on_accessible_stack_fn() - Check whether a stack range is on any
+ * of the possible stacks.
+ *
+ * @tsk:  task whose stack is being unwound
+ * @sp:   stack address being checked
+ * @size: size of the stack range being checked
+ * @info: stack unwinding context
+ */
+typedef bool (*on_accessible_stack_fn)(const struct task_struct *tsk,
+				       unsigned long sp, unsigned long size,
+				       struct stack_info *info);
+
 static inline int unwind_next_common(struct unwind_state *state,
 				     struct stack_info *info,
+				     on_accessible_stack_fn accessible,
 				     stack_trace_translate_fp_fn translate_fp)
 {
 	unsigned long fp = state->fp, kern_fp = fp;
@@ -166,7 +156,7 @@ static inline int unwind_next_common(struct unwind_state *state,
 	if (fp & 0x7)
 		return -EINVAL;
 
-	if (!on_accessible_stack(tsk, fp, 16, info))
+	if (!accessible(tsk, fp, 16, info))
 		return -EINVAL;
 
 	if (test_bit(info->type, state->stacks_done))
@@ -212,19 +202,4 @@ static inline int unwind_next_common(struct unwind_state *state,
 	return 0;
 }
 
-static inline void notrace 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;
-	}
-}
-NOKPROBE_SYMBOL(unwind);
 #endif	/* __ASM_STACKTRACE_COMMON_H */
diff --git a/arch/arm64/include/asm/stacktrace/nvhe.h b/arch/arm64/include/asm/stacktrace/nvhe.h
index 8a5cb96d7143..a096216d8970 100644
--- a/arch/arm64/include/asm/stacktrace/nvhe.h
+++ b/arch/arm64/include/asm/stacktrace/nvhe.h
@@ -37,59 +37,7 @@ static inline void kvm_nvhe_unwind_init(struct unwind_state *state,
 	state->pc = pc;
 }
 
-static inline bool on_hyp_stack(unsigned long sp, unsigned long size,
-				struct stack_info *info);
-
-static inline bool on_accessible_stack(const struct task_struct *tsk,
-				       unsigned long sp, unsigned long size,
-				       struct stack_info *info)
-{
-	if (on_accessible_stack_common(tsk, sp, size, info))
-		return true;
-
-	if (on_hyp_stack(sp, size, info))
-		return true;
-
-	return false;
-}
-
-#ifdef __KVM_NVHE_HYPERVISOR__
-/*
- * Protected nVHE HYP stack unwinder
- *
- * In protected mode, the unwinding is done by the hypervisor in EL2.
- */
-
-#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE
-static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
-				     struct stack_info *info)
-{
-	unsigned long low = (unsigned long)this_cpu_ptr(overflow_stack);
-	unsigned long high = low + OVERFLOW_STACK_SIZE;
-
-	return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);
-}
-
-static inline bool on_hyp_stack(unsigned long sp, unsigned long size,
-				struct stack_info *info)
-{
-	struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
-	unsigned long high = params->stack_hyp_va;
-	unsigned long low = high - PAGE_SIZE;
-
-	return on_stack(sp, size, low, high, STACK_TYPE_HYP, info);
-}
-
-static inline int notrace unwind_next(struct unwind_state *state)
-{
-	struct stack_info info;
-
-	return unwind_next_common(state, &info, NULL);
-}
-NOKPROBE_SYMBOL(unwind_next);
-#endif	/* CONFIG_PROTECTED_NVHE_STACKTRACE */
-
-#else	/* !__KVM_NVHE_HYPERVISOR__ */
+#ifndef __KVM_NVHE_HYPERVISOR__
 /*
  * Conventional (non-protected) nVHE HYP stack unwinder
  *
@@ -142,36 +90,6 @@ static inline bool kvm_nvhe_stack_kern_va(unsigned long *addr,
 	return true;
 }
 
-static inline 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 inline 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 inline int notrace unwind_next(struct unwind_state *state)
-{
-	struct stack_info info;
-
-	return unwind_next_common(state, &info, kvm_nvhe_stack_kern_va);
-}
-NOKPROBE_SYMBOL(unwind_next);
-
 void kvm_nvhe_dump_backtrace(unsigned long hyp_offset);
 
 #endif	/* __KVM_NVHE_HYPERVISOR__ */