[RFC PATCH 03/32] fgraph: Use BUILD_BUG_ON() to make sure we have structures divisible by long
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: 2023-11-05 16:07:21
Also in:
bpf, lkml
Subsystem:
function hooks (ftrace), the rest, tracing · Maintainers:
Steven Rostedt, Masami Hiramatsu, Linus Torvalds
From: Steven Rostedt (VMware) <rostedt@goodmis.org> Instead of using "ALIGN()", use BUILD_BUG_ON() as the structures should always be divisible by sizeof(long). Link: http://lkml.kernel.org/r/20190524111144.GI2589@hirez.programming.kicks-ass.net Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> --- kernel/trace/fgraph.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 30edeb6d4aa9..837daf929d2a 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c@@ -26,10 +26,9 @@ #endif #define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack) -#define FGRAPH_RET_INDEX (ALIGN(FGRAPH_RET_SIZE, sizeof(long)) / sizeof(long)) +#define FGRAPH_RET_INDEX (FGRAPH_RET_SIZE / sizeof(long)) #define SHADOW_STACK_SIZE (PAGE_SIZE) -#define SHADOW_STACK_INDEX \ - (ALIGN(SHADOW_STACK_SIZE, sizeof(long)) / sizeof(long)) +#define SHADOW_STACK_INDEX (SHADOW_STACK_SIZE / sizeof(long)) /* Leave on a buffer at the end */ #define SHADOW_STACK_MAX_INDEX (SHADOW_STACK_INDEX - FGRAPH_RET_INDEX)
@@ -91,6 +90,8 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, if (!current->ret_stack) return -EBUSY; + BUILD_BUG_ON(SHADOW_STACK_SIZE % sizeof(long)); + /* * We must make sure the ret_stack is tested before we read * anything else.
@@ -325,6 +326,8 @@ ftrace_graph_get_ret_stack(struct task_struct *task, int idx) { int index = task->curr_ret_stack; + BUILD_BUG_ON(FGRAPH_RET_SIZE % sizeof(long)); + index -= FGRAPH_RET_INDEX * (idx + 1); if (index < 0) return NULL;