From 394f3f02de5311ea976dd8046304194d22329bbc Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Apr 2025 10:49:06 -0400 Subject: [PATCH] tracing: Use vmap_page_range() to map memmap ring buffer The code to map the physical memory retrieved by memmap currently allocates an array of pages to cover the physical memory and then calls vmap() to map it to a virtual address. Instead of using this temporary array of struct page descriptors, simply use vmap_page_range() that can directly map the contiguous physical memory to a virtual address. Link: https://lore.kernel.org/all/CAHk-=whUOfVucfJRt7E0AH+GV41ELmS4wJqxHDnui6Giddfkzw@mail.gmail.com/ Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Vincent Donnefort Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Jann Horn Link: https://lore.kernel.org/20250402144953.754618481@goodmis.org Suggested-by: Linus Torvalds Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 33 ++++++++++++++++----------------- 1 file changed, 16 insertions(+), 17 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e58b72e61573..f6531cd3176b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -50,6 +50,7 @@ #include #include #include +#include /* vmap_page_range() */ #include /* COMMAND_LINE_SIZE */ @@ -9796,29 +9797,27 @@ static int instance_mkdir(const char *name) return ret; } -static u64 map_pages(u64 start, u64 size) +static u64 map_pages(unsigned long start, unsigned long size) { - struct page **pages; - phys_addr_t page_start; - unsigned int page_count; - unsigned int i; - void *vaddr; - - page_count = DIV_ROUND_UP(size, PAGE_SIZE); + unsigned long vmap_start, vmap_end; + struct vm_struct *area; + int ret; - page_start = start; - pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL); - if (!pages) + area = get_vm_area(size, VM_IOREMAP); + if (!area) return 0; - for (i = 0; i < page_count; i++) { - phys_addr_t addr = page_start + i * PAGE_SIZE; - pages[i] = pfn_to_page(addr >> PAGE_SHIFT); + vmap_start = (unsigned long) area->addr; + vmap_end = vmap_start + size; + + ret = vmap_page_range(vmap_start, vmap_end, + start, pgprot_nx(PAGE_KERNEL)); + if (ret < 0) { + free_vm_area(area); + return 0; } - vaddr = vmap(pages, page_count, VM_MAP, PAGE_KERNEL); - kfree(pages); - return (u64)(unsigned long)vaddr; + return (u64)vmap_start; } /**