diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2023-09-16 22:20:03 +0300 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2023-09-18 18:03:45 +0300 |
| commit | 5634c90fd8553de7cbafecd048d0273690a2e84e (patch) | |
| tree | c5c9c0698e4b3a1d727fb8cc6067169aa89cebff /include | |
| parent | d818b56f77521ecc5e3eda71dc9b2beb3d6681e3 (diff) | |
| download | linux-5634c90fd8553de7cbafecd048d0273690a2e84e.tar.xz | |
printk: nbcon: Add buffer management
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
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/console.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/console.h b/include/linux/console.h index 98210fd01f18..ca1ef8700e55 100644 --- 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 |