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Date: Mon, 17 Jan 2022 08:56:01 -0600
From: madvenka@...ux.microsoft.com
To: mark.rutland@....com, broonie@...nel.org, jpoimboe@...hat.com,
ardb@...nel.org, nobuta.keiya@...itsu.com,
sjitindarsingh@...il.com, catalin.marinas@....com, will@...nel.org,
jmorris@...ei.org, linux-arm-kernel@...ts.infradead.org,
live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
madvenka@...ux.microsoft.com
Subject: [PATCH v13 04/11] arm64: Split unwind_init()
From: "Madhavan T. Venkataraman" <madvenka@...ux.microsoft.com>
unwind_init() is currently a single function that initializes all of the
unwind state. Split it into the following functions and call them
appropriately:
- unwind_init_from_regs() - initialize from regs passed by caller.
- unwind_init_from_current() - initialize for the current task
from the caller of arch_stack_walk().
- unwind_init_from_task() - initialize from the saved state of a
task other than the current task. In this case, the other
task must not be running.
This is done for two reasons:
- the different ways of initializing are clear
- specialized code can be added to each initializer in the future.
Signed-off-by: Madhavan T. Venkataraman <madvenka@...ux.microsoft.com>
---
arch/arm64/kernel/stacktrace.c | 54 +++++++++++++++++++++++++++-------
1 file changed, 44 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index a1a7ff93b84f..b2b568e5deba 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -33,11 +33,8 @@
*/
-static void unwind_init(struct unwind_state *state, unsigned long fp,
- unsigned long pc)
+static void unwind_init_common(struct unwind_state *state)
{
- state->fp = fp;
- state->pc = pc;
#ifdef CONFIG_KRETPROBES
state->kr_cur = NULL;
#endif
@@ -56,6 +53,46 @@ static void unwind_init(struct unwind_state *state, unsigned long fp,
state->prev_type = STACK_TYPE_UNKNOWN;
}
+/*
+ * TODO: document requirements here.
+ */
+static inline void unwind_init_from_regs(struct unwind_state *state,
+ struct pt_regs *regs)
+{
+ unwind_init_common(state);
+
+ state->fp = regs->regs[29];
+ state->pc = regs->pc;
+}
+
+/*
+ * TODO: document requirements here.
+ *
+ * Note: this is always inlined, and we expect our caller to be a noinline
+ * function, such that this starts from our caller's caller.
+ */
+static __always_inline void unwind_init_from_current(struct unwind_state *state)
+{
+ unwind_init_common(state);
+
+ state->fp = (unsigned long)__builtin_frame_address(1);
+ state->pc = (unsigned long)__builtin_return_address(0);
+}
+
+/*
+ * TODO: document requirements here.
+ *
+ * The caller guarantees that the task is not running.
+ */
+static inline void unwind_init_from_task(struct unwind_state *state,
+ struct task_struct *task)
+{
+ unwind_init_common(state);
+
+ state->fp = thread_saved_fp(task);
+ state->pc = thread_saved_pc(task);
+}
+
/*
* Unwind from one frame record (A) to the next frame record (B).
*
@@ -195,14 +232,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
struct unwind_state state;
if (regs)
- unwind_init(&state, regs->regs[29], regs->pc);
+ unwind_init_from_regs(&state, regs);
else if (task == current)
- unwind_init(&state,
- (unsigned long)__builtin_frame_address(1),
- (unsigned long)__builtin_return_address(0));
+ unwind_init_from_current(&state);
else
- unwind_init(&state, thread_saved_fp(task),
- thread_saved_pc(task));
+ unwind_init_from_task(&state, task);
unwind(task, &state, consume_entry, cookie);
}
--
2.25.1
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