From: Steven Rostedt <rostedt@xxxxxxxxxxx> [ Upstream commit c44a14f216f45d8bf1634b52854a699d7090f1e8 ] Enforce that the address and the size of the memory used by the persistent ring buffer is page aligned. Also update the documentation to reflect this requirement. Link: https://lore.kernel.org/all/CAHk-=whUOfVucfJRt7E0AH+GV41ELmS4wJqxHDnui6Giddfkzw@xxxxxxxxxxxxxx/ Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Vincent Donnefort <vdonnefort@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Link: https://lore.kernel.org/20250402144953.412882844@xxxxxxxxxxx Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- Documentation/admin-guide/kernel-parameters.txt | 2 ++ Documentation/trace/debugging.rst | 2 ++ kernel/trace/trace.c | 10 ++++++++++ 3 files changed, 14 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb8752b42ec85..71861643ef143 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -7241,6 +7241,8 @@ This is just one of many ways that can clear memory. Make sure your system keeps the content of memory across reboots before relying on this option. + NB: Both the mapped address and size must be page aligned for the architecture. + See also Documentation/trace/debugging.rst diff --git a/Documentation/trace/debugging.rst b/Documentation/trace/debugging.rst index 54fb16239d703..d54bc500af80b 100644 --- a/Documentation/trace/debugging.rst +++ b/Documentation/trace/debugging.rst @@ -136,6 +136,8 @@ kernel, so only the same kernel is guaranteed to work if the mapping is preserved. Switching to a different kernel version may find a different layout and mark the buffer as invalid. +NB: Both the mapped address and size must be page aligned for the architecture. + Using trace_printk() in the boot instance ----------------------------------------- By default, the content of trace_printk() goes into the top level tracing diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0e6d517e74e0f..50aa6d5908329 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10427,6 +10427,16 @@ __init static void enable_instances(void) } if (start) { + /* Start and size must be page aligned */ + if (start & ~PAGE_MASK) { + pr_warn("Tracing: mapping start addr %pa is not page aligned\n", &start); + continue; + } + if (size & ~PAGE_MASK) { + pr_warn("Tracing: mapping size %pa is not page aligned\n", &size); + continue; + } + addr = map_pages(start, size); if (addr) { pr_info("Tracing: mapped boot instance %s at physical memory %pa of size 0x%lx\n", -- 2.39.5
