diff options
Diffstat (limited to 'debian/patches-rt/0078-printk-nbcon-Add-buffer-management.patch')
| -rw-r--r-- | debian/patches-rt/0078-printk-nbcon-Add-buffer-management.patch | 311 |
1 files changed, 0 insertions, 311 deletions
diff --git a/debian/patches-rt/0078-printk-nbcon-Add-buffer-management.patch b/debian/patches-rt/0078-printk-nbcon-Add-buffer-management.patch deleted file mode 100644 index ea96abd7e..000000000 --- a/debian/patches-rt/0078-printk-nbcon-Add-buffer-management.patch +++ /dev/null @@ -1,311 +0,0 @@ -From: Thomas Gleixner <tglx@linutronix.de> -Date: Sat, 16 Sep 2023 21:26:03 +0206 -Subject: [PATCH 078/134] printk: nbcon: Add buffer management -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz - -In case of hostile takeovers it must be ensured that the previous -owner cannot scribble over the output buffer of the emergency/panic -context. This is achieved by: - - - Adding a global output buffer instance for the panic context. - This is the only situation where hostile takeovers can occur and - there is always at most 1 panic context. - - - Allocating an output buffer per non-boot console upon console - registration. This buffer is used by the console owner when not - in panic context. (For boot consoles, the existing shared global - legacy output buffer is used instead. Boot console printing will - be synchronized with legacy console printing.) - - - Choosing the appropriate buffer is handled in the acquire/release - functions. - -Co-developed-by: John Ogness <john.ogness@linutronix.de> -Signed-off-by: John Ogness <john.ogness@linutronix.de> -Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> -Reviewed-by: Petr Mladek <pmladek@suse.com> -Signed-off-by: Petr Mladek <pmladek@suse.com> -Link: https://lore.kernel.org/r/20230916192007.608398-5-john.ogness@linutronix.de -Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> ---- - include/linux/console.h | 7 ++++ - kernel/printk/internal.h | 12 ++++++- - kernel/printk/nbcon.c | 73 +++++++++++++++++++++++++++++++++++++++++++---- - kernel/printk/printk.c | 22 +++++++++----- - 4 files changed, 99 insertions(+), 15 deletions(-) - ---- a/include/linux/console.h -+++ b/include/linux/console.h -@@ -231,6 +231,7 @@ enum nbcon_prio { - }; - - struct console; -+struct printk_buffers; - - /** - * struct nbcon_context - Context for console acquire/release -@@ -241,6 +242,7 @@ struct console; - * be used only with NBCON_PRIO_PANIC @prio. It - * might cause a system freeze when the console - * is used later. -+ * @pbufs: Pointer to the text buffer for this context - */ - struct nbcon_context { - /* members set by caller */ -@@ -248,6 +250,9 @@ struct nbcon_context { - unsigned int spinwait_max_us; - enum nbcon_prio prio; - unsigned int allow_unsafe_takeover : 1; -+ -+ /* members set by acquire */ -+ struct printk_buffers *pbufs; - }; - - /** -@@ -271,6 +276,7 @@ struct nbcon_context { - * @node: hlist node for the console list - * - * @nbcon_state: State for nbcon consoles -+ * @pbufs: Pointer to nbcon private buffer - */ - struct console { - char name[16]; -@@ -293,6 +299,7 @@ struct console { - - /* nbcon console specific members */ - atomic_t __private nbcon_state; -+ struct printk_buffers *pbufs; - }; - - #ifdef CONFIG_LOCKDEP ---- a/kernel/printk/internal.h -+++ b/kernel/printk/internal.h -@@ -13,6 +13,12 @@ int devkmsg_sysctl_set_loglvl(struct ctl - #define printk_sysctl_init() do { } while (0) - #endif - -+#define con_printk(lvl, con, fmt, ...) \ -+ printk(lvl pr_fmt("%s%sconsole [%s%d] " fmt), \ -+ (con->flags & CON_NBCON) ? "" : "legacy ", \ -+ (con->flags & CON_BOOT) ? "boot" : "", \ -+ con->name, con->index, ##__VA_ARGS__) -+ - #ifdef CONFIG_PRINTK - - #ifdef CONFIG_PRINTK_CALLER -@@ -63,8 +69,9 @@ void defer_console_output(void); - u16 printk_parse_prefix(const char *text, int *level, - enum printk_info_flags *flags); - -+bool nbcon_alloc(struct console *con); - void nbcon_init(struct console *con); --void nbcon_cleanup(struct console *con); -+void nbcon_free(struct console *con); - - #else - -@@ -81,8 +88,9 @@ void nbcon_cleanup(struct console *con); - #define printk_safe_exit_irqrestore(flags) local_irq_restore(flags) - - static inline bool printk_percpu_data_ready(void) { return false; } -+static inline bool nbcon_alloc(struct console *con) { return false; } - static inline void nbcon_init(struct console *con) { } --static inline void nbcon_cleanup(struct console *con) { } -+static inline void nbcon_free(struct console *con) { } - - #endif /* CONFIG_PRINTK */ - ---- a/kernel/printk/nbcon.c -+++ b/kernel/printk/nbcon.c -@@ -5,6 +5,7 @@ - #include <linux/kernel.h> - #include <linux/console.h> - #include <linux/delay.h> -+#include <linux/slab.h> - #include "internal.h" - /* - * Printk console printing implementation for consoles which does not depend -@@ -70,6 +71,10 @@ - * console is an unsafe state. It is used only in panic() by the final - * attempt to flush consoles in a try and hope mode. - * -+ * Note that separate record buffers are used in panic(). As a result, -+ * the messages can be read and formatted without any risk even after -+ * using the hostile takeover in unsafe state. -+ * - * The release function simply clears the 'prio' field. - * - * All operations on @console::nbcon_state are atomic cmpxchg based to -@@ -459,6 +464,8 @@ static int nbcon_context_try_acquire_hos - return 0; - } - -+static struct printk_buffers panic_nbcon_pbufs; -+ - /** - * nbcon_context_try_acquire - Try to acquire nbcon console - * @ctxt: The context of the caller -@@ -473,6 +480,7 @@ static int nbcon_context_try_acquire_hos - __maybe_unused - static bool nbcon_context_try_acquire(struct nbcon_context *ctxt) - { -+ unsigned int cpu = smp_processor_id(); - struct console *con = ctxt->console; - struct nbcon_state cur; - int err; -@@ -491,7 +499,18 @@ static bool nbcon_context_try_acquire(st - - err = nbcon_context_try_acquire_hostile(ctxt, &cur); - out: -- return !err; -+ if (err) -+ return false; -+ -+ /* Acquire succeeded. */ -+ -+ /* Assign the appropriate buffer for this context. */ -+ if (atomic_read(&panic_cpu) == cpu) -+ ctxt->pbufs = &panic_nbcon_pbufs; -+ else -+ ctxt->pbufs = con->pbufs; -+ -+ return true; - } - - static bool nbcon_owner_matches(struct nbcon_state *cur, int expected_cpu, -@@ -530,7 +549,7 @@ static void nbcon_context_release(struct - - do { - if (!nbcon_owner_matches(&cur, cpu, ctxt->prio)) -- return; -+ break; - - new.atom = cur.atom; - new.prio = NBCON_PRIO_NONE; -@@ -542,26 +561,70 @@ static void nbcon_context_release(struct - new.unsafe |= cur.unsafe_takeover; - - } while (!nbcon_state_try_cmpxchg(con, &cur, &new)); -+ -+ ctxt->pbufs = NULL; -+} -+ -+/** -+ * nbcon_alloc - Allocate buffers needed by the nbcon console -+ * @con: Console to allocate buffers for -+ * -+ * Return: True on success. False otherwise and the console cannot -+ * be used. -+ * -+ * This is not part of nbcon_init() because buffer allocation must -+ * be performed earlier in the console registration process. -+ */ -+bool nbcon_alloc(struct console *con) -+{ -+ if (con->flags & CON_BOOT) { -+ /* -+ * Boot console printing is synchronized with legacy console -+ * printing, so boot consoles can share the same global printk -+ * buffers. -+ */ -+ con->pbufs = &printk_shared_pbufs; -+ } else { -+ con->pbufs = kmalloc(sizeof(*con->pbufs), GFP_KERNEL); -+ if (!con->pbufs) { -+ con_printk(KERN_ERR, con, "failed to allocate printing buffer\n"); -+ return false; -+ } -+ } -+ -+ return true; - } - - /** - * nbcon_init - Initialize the nbcon console specific data - * @con: Console to initialize -+ * -+ * nbcon_alloc() *must* be called and succeed before this function -+ * is called. - */ - void nbcon_init(struct console *con) - { - struct nbcon_state state = { }; - -+ /* nbcon_alloc() must have been called and successful! */ -+ BUG_ON(!con->pbufs); -+ - nbcon_state_set(con, &state); - } - - /** -- * nbcon_cleanup - Cleanup the nbcon console specific data -- * @con: Console to cleanup -+ * nbcon_free - Free and cleanup the nbcon console specific data -+ * @con: Console to free/cleanup nbcon data - */ --void nbcon_cleanup(struct console *con) -+void nbcon_free(struct console *con) - { - struct nbcon_state state = { }; - - nbcon_state_set(con, &state); -+ -+ /* Boot consoles share global printk buffers. */ -+ if (!(con->flags & CON_BOOT)) -+ kfree(con->pbufs); -+ -+ con->pbufs = NULL; - } ---- a/kernel/printk/printk.c -+++ b/kernel/printk/printk.c -@@ -3331,12 +3331,6 @@ static void try_enable_default_console(s - newcon->flags |= CON_CONSDEV; - } - --#define con_printk(lvl, con, fmt, ...) \ -- printk(lvl pr_fmt("%s%sconsole [%s%d] " fmt), \ -- (con->flags & CON_NBCON) ? "" : "legacy ", \ -- (con->flags & CON_BOOT) ? "boot" : "", \ -- con->name, con->index, ##__VA_ARGS__) -- - static void console_init_seq(struct console *newcon, bool bootcon_registered) - { - struct console *con; -@@ -3450,6 +3444,15 @@ void register_console(struct console *ne - goto unlock; - } - -+ if (newcon->flags & CON_NBCON) { -+ /* -+ * Ensure the nbcon console buffers can be allocated -+ * before modifying any global data. -+ */ -+ if (!nbcon_alloc(newcon)) -+ goto unlock; -+ } -+ - /* - * See if we want to enable this console driver by default. - * -@@ -3477,8 +3480,11 @@ void register_console(struct console *ne - err = try_enable_preferred_console(newcon, false); - - /* printk() messages are not printed to the Braille console. */ -- if (err || newcon->flags & CON_BRL) -+ if (err || newcon->flags & CON_BRL) { -+ if (newcon->flags & CON_NBCON) -+ nbcon_free(newcon); - goto unlock; -+ } - - /* - * If we have a bootconsole, and are switching to a real console, -@@ -3589,7 +3595,7 @@ static int unregister_console_locked(str - synchronize_srcu(&console_srcu); - - if (console->flags & CON_NBCON) -- nbcon_cleanup(console); -+ nbcon_free(console); - - console_sysfs_notify(); - |