Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
tracing: load/unload page callbacks for simple_ring_buffer
Add load/unload callback used for each admitted page in the ring-buffer.
This will be later useful for the pKVM hypervisor which uses a different
VA space and need to dynamically map/unmap the ring-buffer pages.
Link: https://patch.msgid.link/20260309162516.2623589-18-vdonnefort@google.com
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
authored by
Vincent Donnefort
and committed by
Steven Rostedt (Google)
63592308
c88d5105
+112
-51
+8
include/linux/simple_ring_buffer.h
+8
include/linux/simple_ring_buffer.h
···
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int simple_ring_buffer_swap_reader_page(struct simple_rb_per_cpu *cpu_buffer);
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int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer,
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struct simple_buffer_page *bpages,
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const struct ring_buffer_desc *desc,
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void *(*load_page)(unsigned long va),
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void (*unload_page)(void *va));
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void simple_ring_buffer_unload_mm(struct simple_rb_per_cpu *cpu_buffer,
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void (*unload_page)(void *));
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#endif
+104
-51
kernel/trace/simple_ring_buffer.c
+104
-51
kernel/trace/simple_ring_buffer.c
···
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local_set(&bpage->page->commit, 0);
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}
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-
static void simple_bpage_init(struct simple_buffer_page *bpage, unsigned long page)
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static void simple_bpage_init(struct simple_buffer_page *bpage, void *page)
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{
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INIT_LIST_HEAD(&bpage->link);
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bpage->page = (struct buffer_data_page *)page;
···
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}
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EXPORT_SYMBOL_GPL(simple_ring_buffer_reset);
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int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer,
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struct simple_buffer_page *bpages,
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const struct ring_buffer_desc *desc,
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void *(*load_page)(unsigned long va),
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void (*unload_page)(void *va))
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{
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struct simple_buffer_page *bpage = bpages;
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int ret = 0;
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void *page;
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int i;
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/* At least 1 reader page and two pages in the ring-buffer */
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if (desc->nr_page_va < 3)
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return -EINVAL;
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memset(cpu_buffer, 0, sizeof(*cpu_buffer));
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cpu_buffer->meta = load_page(desc->meta_va);
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if (!cpu_buffer->meta)
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return -EINVAL;
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memset(cpu_buffer->meta, 0, sizeof(*cpu_buffer->meta));
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cpu_buffer->meta->meta_page_size = PAGE_SIZE;
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cpu_buffer->meta->nr_subbufs = cpu_buffer->nr_pages;
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/* The reader page is not part of the ring initially */
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page = load_page(desc->page_va[0]);
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if (!page) {
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unload_page(cpu_buffer->meta);
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return -EINVAL;
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}
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simple_bpage_init(bpage, page);
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bpage->id = 0;
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cpu_buffer->nr_pages = 1;
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cpu_buffer->reader_page = bpage;
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cpu_buffer->tail_page = bpage + 1;
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cpu_buffer->head_page = bpage + 1;
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for (i = 1; i < desc->nr_page_va; i++) {
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page = load_page(desc->page_va[i]);
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if (!page) {
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ret = -EINVAL;
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break;
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}
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simple_bpage_init(++bpage, page);
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bpage->link.next = &(bpage + 1)->link;
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bpage->link.prev = &(bpage - 1)->link;
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bpage->id = i;
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cpu_buffer->nr_pages = i + 1;
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}
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if (ret) {
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for (i--; i >= 0; i--)
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unload_page((void *)desc->page_va[i]);
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unload_page(cpu_buffer->meta);
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return ret;
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}
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/* Close the ring */
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bpage->link.next = &cpu_buffer->tail_page->link;
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cpu_buffer->tail_page->link.prev = &bpage->link;
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/* The last init'ed page points to the head page */
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simple_bpage_set_head_link(bpage);
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cpu_buffer->bpages = bpages;
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return 0;
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}
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static void *__load_page(unsigned long page)
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{
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return (void *)page;
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}
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static void __unload_page(void *page) { }
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/**
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* simple_ring_buffer_init - Init @cpu_buffer based on @desc
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* @cpu_buffer: A simple_rb_per_cpu buffer to init, allocated by the caller.
···
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int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_buffer_page *bpages,
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const struct ring_buffer_desc *desc)
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{
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struct simple_buffer_page *bpage = bpages;
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int i;
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/* At least 1 reader page and two pages in the ring-buffer */
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if (desc->nr_page_va < 3)
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return -EINVAL;
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memset(cpu_buffer, 0, sizeof(*cpu_buffer));
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cpu_buffer->bpages = bpages;
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cpu_buffer->meta = (void *)desc->meta_va;
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memset(cpu_buffer->meta, 0, sizeof(*cpu_buffer->meta));
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cpu_buffer->meta->meta_page_size = PAGE_SIZE;
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cpu_buffer->meta->nr_subbufs = cpu_buffer->nr_pages;
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/* The reader page is not part of the ring initially */
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simple_bpage_init(bpage, desc->page_va[0]);
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bpage->id = 0;
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cpu_buffer->nr_pages = 1;
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cpu_buffer->reader_page = bpage;
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cpu_buffer->tail_page = bpage + 1;
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cpu_buffer->head_page = bpage + 1;
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for (i = 1; i < desc->nr_page_va; i++) {
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simple_bpage_init(++bpage, desc->page_va[i]);
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bpage->link.next = &(bpage + 1)->link;
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bpage->link.prev = &(bpage - 1)->link;
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bpage->id = i;
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cpu_buffer->nr_pages = i + 1;
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}
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/* Close the ring */
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bpage->link.next = &cpu_buffer->tail_page->link;
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cpu_buffer->tail_page->link.prev = &bpage->link;
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/* The last init'ed page points to the head page */
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simple_bpage_set_head_link(bpage);
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return 0;
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return simple_ring_buffer_init_mm(cpu_buffer, bpages, desc, __load_page, __unload_page);
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}
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EXPORT_SYMBOL_GPL(simple_ring_buffer_init);
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void simple_ring_buffer_unload_mm(struct simple_rb_per_cpu *cpu_buffer,
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void (*unload_page)(void *))
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{
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int p;
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if (!simple_rb_loaded(cpu_buffer))
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return;
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simple_rb_enable_tracing(cpu_buffer, false);
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unload_page(cpu_buffer->meta);
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for (p = 0; p < cpu_buffer->nr_pages; p++)
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unload_page(cpu_buffer->bpages[p].page);
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cpu_buffer->bpages = NULL;
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}
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/**
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* simple_ring_buffer_unload - Prepare @cpu_buffer for deletion
···
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*/
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void simple_ring_buffer_unload(struct simple_rb_per_cpu *cpu_buffer)
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{
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if (!simple_rb_loaded(cpu_buffer))
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return;
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simple_rb_enable_tracing(cpu_buffer, false);
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cpu_buffer->bpages = NULL;
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return simple_ring_buffer_unload_mm(cpu_buffer, __unload_page);
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}
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EXPORT_SYMBOL_GPL(simple_ring_buffer_unload);
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