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Fri, 06 Mar 2026 06:36:09 -0800 (PST) Date: Fri, 6 Mar 2026 14:35:21 +0000 In-Reply-To: <20260306143536.339777-1-vdonnefort@google.com> Mime-Version: 1.0 References: <20260306143536.339777-1-vdonnefort@google.com> X-Mailer: git-send-email 2.53.0.473.g4a7958ca14-goog Message-ID: <20260306143536.339777-18-vdonnefort@google.com> Subject: [PATCH v13 17/32] tracing: load/unload page callbacks for simple_ring_buffer From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260306_063612_106980_6E2F089A X-CRM114-Status: GOOD ( 16.19 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort diff --git a/include/linux/simple_ring_buffer.h b/include/linux/simple_ring_buffer.h index 2c4c0ae336bc..21aec556293e 100644 --- a/include/linux/simple_ring_buffer.h +++ b/include/linux/simple_ring_buffer.h @@ -54,4 +54,12 @@ int simple_ring_buffer_reset(struct simple_rb_per_cpu *cpu_buffer); int simple_ring_buffer_swap_reader_page(struct simple_rb_per_cpu *cpu_buffer); +int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer, + struct simple_buffer_page *bpages, + const struct ring_buffer_desc *desc, + void *(*load_page)(unsigned long va), + void (*unload_page)(void *va)); + +void simple_ring_buffer_unload_mm(struct simple_rb_per_cpu *cpu_buffer, + void (*unload_page)(void *)); #endif diff --git a/kernel/trace/simple_ring_buffer.c b/kernel/trace/simple_ring_buffer.c index 15df9781411b..02af2297ae5a 100644 --- a/kernel/trace/simple_ring_buffer.c +++ b/kernel/trace/simple_ring_buffer.c @@ -71,7 +71,7 @@ static void simple_bpage_reset(struct simple_buffer_page *bpage) local_set(&bpage->page->commit, 0); } -static void simple_bpage_init(struct simple_buffer_page *bpage, unsigned long page) +static void simple_bpage_init(struct simple_buffer_page *bpage, void *page) { INIT_LIST_HEAD(&bpage->link); bpage->page = (struct buffer_data_page *)page; @@ -372,18 +372,15 @@ int simple_ring_buffer_reset(struct simple_rb_per_cpu *cpu_buffer) } EXPORT_SYMBOL_GPL(simple_ring_buffer_reset); -/** - * simple_ring_buffer_init - Init @cpu_buffer based on @desc - * @cpu_buffer: A simple_rb_per_cpu buffer to init, allocated by the caller. - * @bpages: Array of simple_buffer_pages, with as many elements as @desc->nr_page_va - * @desc: A ring_buffer_desc - * - * Returns 0 on success or -EINVAL if the content of @desc is invalid - */ -int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_buffer_page *bpages, - const struct ring_buffer_desc *desc) +int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer, + struct simple_buffer_page *bpages, + const struct ring_buffer_desc *desc, + void *(*load_page)(unsigned long va), + void (*unload_page)(void *va)) { struct simple_buffer_page *bpage = bpages; + int ret = 0; + void *page; int i; /* At least 1 reader page and two pages in the ring-buffer */ @@ -392,15 +389,22 @@ int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_ memset(cpu_buffer, 0, sizeof(*cpu_buffer)); - cpu_buffer->bpages = bpages; + cpu_buffer->meta = load_page(desc->meta_va); + if (!cpu_buffer->meta) + return -EINVAL; - cpu_buffer->meta = (void *)desc->meta_va; memset(cpu_buffer->meta, 0, sizeof(*cpu_buffer->meta)); cpu_buffer->meta->meta_page_size = PAGE_SIZE; cpu_buffer->meta->nr_subbufs = cpu_buffer->nr_pages; /* The reader page is not part of the ring initially */ - simple_bpage_init(bpage, desc->page_va[0]); + page = load_page(desc->page_va[0]); + if (!page) { + unload_page(cpu_buffer->meta); + return -EINVAL; + } + + simple_bpage_init(bpage, page); bpage->id = 0; cpu_buffer->nr_pages = 1; @@ -410,7 +414,13 @@ int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_ cpu_buffer->head_page = bpage + 1; for (i = 1; i < desc->nr_page_va; i++) { - simple_bpage_init(++bpage, desc->page_va[i]); + page = load_page(desc->page_va[i]); + if (!page) { + ret = -EINVAL; + break; + } + + simple_bpage_init(++bpage, page); bpage->link.next = &(bpage + 1)->link; bpage->link.prev = &(bpage - 1)->link; @@ -419,6 +429,14 @@ int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_ cpu_buffer->nr_pages = i + 1; } + if (ret) { + for (i--; i >= 0; i--) + unload_page((void *)desc->page_va[i]); + unload_page(cpu_buffer->meta); + + return ret; + } + /* Close the ring */ bpage->link.next = &cpu_buffer->tail_page->link; cpu_buffer->tail_page->link.prev = &bpage->link; @@ -426,23 +444,58 @@ int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_ /* The last init'ed page points to the head page */ simple_bpage_set_head_link(bpage); + cpu_buffer->bpages = bpages; + return 0; } -EXPORT_SYMBOL_GPL(simple_ring_buffer_init); + +static void *__load_page(unsigned long page) +{ + return (void *)page; +} + +static void __unload_page(void *page) { } /** - * simple_ring_buffer_unload - Prepare @cpu_buffer for deletion - * @cpu_buffer: A simple_rb_per_cpu that will be deleted. + * simple_ring_buffer_init - Init @cpu_buffer based on @desc + * @cpu_buffer: A simple_rb_per_cpu buffer to init, allocated by the caller. + * @bpages: Array of simple_buffer_pages, with as many elements as @desc->nr_page_va + * @desc: A ring_buffer_desc + * + * Returns 0 on success or -EINVAL if the content of @desc is invalid */ -void simple_ring_buffer_unload(struct simple_rb_per_cpu *cpu_buffer) +int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_buffer_page *bpages, + const struct ring_buffer_desc *desc) +{ + return simple_ring_buffer_init_mm(cpu_buffer, bpages, desc, __load_page, __unload_page); +} +EXPORT_SYMBOL_GPL(simple_ring_buffer_init); + +void simple_ring_buffer_unload_mm(struct simple_rb_per_cpu *cpu_buffer, + void (*unload_page)(void *)) { + int p; + if (!simple_rb_loaded(cpu_buffer)) return; simple_rb_enable_tracing(cpu_buffer, false); + unload_page(cpu_buffer->meta); + for (p = 0; p < cpu_buffer->nr_pages; p++) + unload_page(cpu_buffer->bpages[p].page); + cpu_buffer->bpages = NULL; } + +/** + * simple_ring_buffer_unload - Prepare @cpu_buffer for deletion + * @cpu_buffer: A simple_rb_per_cpu that will be deleted. + */ +void simple_ring_buffer_unload(struct simple_rb_per_cpu *cpu_buffer) +{ + return simple_ring_buffer_unload_mm(cpu_buffer, __unload_page); +} EXPORT_SYMBOL_GPL(simple_ring_buffer_unload); /** -- 2.53.0.473.g4a7958ca14-goog