arm64: stacktrace: rework stack boundary discovery

In subsequent patches we'll want to acquire the stack boundaries
ahead-of-time, and we'll need to be able to acquire the relevant
stack_info regardless of whether we have an object the happens to be on
the stack.

This patch replaces the on_XXX_stack() helpers with stackinfo_get_XXX()
helpers, with the caller being responsible for the checking whether an
object is on a relevant stack. For the moment this is moved into the
on_accessible_stack() functions, making these slightly larger;
subsequent patches will remove the on_accessible_stack() functions and
simplify the logic.

The on_irq_stack() and on_task_stack() helpers are kept as these are
used by IRQ entry sequences and stackleak respectively. As they're only
used as predicates, the stack_info pointer parameter is removed in both
cases.

As the on_accessible_stack() functions are always passed a non-NULL info
pointer, these now update info unconditionally. When updating the type
to STACK_TYPE_UNKNOWN, the low/high bounds are also modified, but as
these will not be consumed this should have no adverse affect.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220901130646.1316937-7-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 27 insertions, 10 deletions

diff --git a/arch/arm64/kvm/hyp/nvhe/stacktrace.c b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
index 579b46aa9a55..5da0d44f61b7 100644
--- a/arch/arm64/kvm/hyp/nvhe/stacktrace.c
+++ b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
@@ -39,34 +39,51 @@ static void hyp_prepare_backtrace(unsigned long fp, unsigned long pc)
 
 DEFINE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)], pkvm_stacktrace);
 
-static bool on_overflow_stack(unsigned long sp, unsigned long size,
-			      struct stack_info *info)
+static struct stack_info stackinfo_get_overflow(void)
 {
 	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);
+	return (struct stack_info) {
+		.low = low,
+		.high = high,
+		.type = STACK_TYPE_OVERFLOW,
+	};
 }
 
-static bool on_hyp_stack(unsigned long sp, unsigned long size,
-			      struct stack_info *info)
+static struct stack_info stackinfo_get_hyp(void)
 {
 	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);
+	return (struct stack_info) {
+		.low = low,
+		.high = high,
+		.type = STACK_TYPE_HYP,
+	};
 }
 
 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;
+	struct stack_info tmp;
 
-	return (on_overflow_stack(sp, size, info) ||
-		on_hyp_stack(sp, size, info));
+	tmp = stackinfo_get_overflow();
+	if (stackinfo_on_stack(&tmp, sp, size))
+		goto found;
+
+	tmp = stackinfo_get_hyp();
+	if (stackinfo_on_stack(&tmp, sp, size))
+		goto found;
+
+	*info = stackinfo_get_unknown();
+	return false;
+
+found:
+	*info = tmp;
+	return true;
 }
 
 static int unwind_next(struct unwind_state *state)