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| author | Ryan Roberts <ryan.roberts@arm.com> | 2024-10-21 15:18:31 +0100 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-10-30 19:41:07 -0400 |
| commit | 2c33155ef678033b8a3105b824cdef930f05b47d (patch) | |
| tree | aadef3fb8d99703fe10594fd451f47811c04bfad /kernel/trace | |
| parent | eb887c4567d1b0e7684c026fe7df44afa96589e6 (diff) | |
| download | lwn-2c33155ef678033b8a3105b824cdef930f05b47d.tar.gz lwn-2c33155ef678033b8a3105b824cdef930f05b47d.zip | |
tracing: Make percpu stack trace buffer invariant to PAGE_SIZE
Previously the size of "struct ftrace_stacks" depended upon PAGE_SIZE.
For the common 4K page size, on a 64-bit system, sizeof(struct
ftrace_stacks) was 32K. But for a 64K page size, sizeof(struct
ftrace_stacks) was 512K.
But ftrace stack usage requirements should be invariant to page size. So
let's redefine FTRACE_KSTACK_ENTRIES so that "struct ftrace_stacks" is
always sized at 32K for 64-bit and 16K for 32-bit.
As a side effect, it removes the PAGE_SIZE compile-time constant
assumption from this code, which is required to reach the goal of
boot-time page size selection.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20241021141832.3668264-1-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index bdb776e6ceb9..f1d613d924e9 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2898,7 +2898,7 @@ trace_function(struct trace_array *tr, unsigned long ip, unsigned long /* Allow 4 levels of nesting: normal, softirq, irq, NMI */ #define FTRACE_KSTACK_NESTING 4 -#define FTRACE_KSTACK_ENTRIES (PAGE_SIZE / FTRACE_KSTACK_NESTING) +#define FTRACE_KSTACK_ENTRIES (SZ_4K / FTRACE_KSTACK_NESTING) struct ftrace_stack { unsigned long calls[FTRACE_KSTACK_ENTRIES]; |