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https://github.com/OpenVoiceOS/OpenVoiceOS
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106 lines
3.6 KiB
Diff
106 lines
3.6 KiB
Diff
From 56ceb90cac5939a9e30555e91c08a1a1dcf6ddae Mon Sep 17 00:00:00 2001
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From: John Ogness <john.ogness@linutronix.de>
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Date: Fri, 20 Oct 2023 10:03:42 +0000
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Subject: [PATCH 137/198] printk: nbcon: Add unsafe flushing on panic
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Add nbcon_atomic_flush_unsafe() to flush all nbcon consoles
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using the write_atomic() callback and allowing unsafe hostile
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takeovers. Call this at the end of panic() as a final attempt
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to flush any pending messages.
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Note that legacy consoles use unsafe methods for flushing
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from the beginning of panic (see bust_spinlocks()). Therefore,
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systems using both legacy and nbcon consoles may still fail to
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see panic messages due to unsafe legacy console usage.
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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include/linux/printk.h | 5 +++++
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kernel/panic.c | 1 +
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kernel/printk/nbcon.c | 18 ++++++++++++++++--
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3 files changed, 22 insertions(+), 2 deletions(-)
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diff --git a/include/linux/printk.h b/include/linux/printk.h
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index 2aa57a870caf..e26dcf63efb1 100644
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--- a/include/linux/printk.h
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+++ b/include/linux/printk.h
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@@ -199,6 +199,7 @@ extern asmlinkage void dump_stack(void) __cold;
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void printk_trigger_flush(void);
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extern void nbcon_acquire(struct uart_port *up);
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extern void nbcon_release(struct uart_port *up);
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+void nbcon_atomic_flush_unsafe(void);
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#else
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static inline __printf(1, 0)
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int vprintk(const char *s, va_list args)
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@@ -287,6 +288,10 @@ static inline void nbcon_release(struct uart_port *up)
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{
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}
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+static inline void nbcon_atomic_flush_unsafe(void)
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+{
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+}
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+
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#endif
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#ifdef CONFIG_SMP
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diff --git a/kernel/panic.c b/kernel/panic.c
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index ef9f9a4e928d..219b69fbe829 100644
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--- a/kernel/panic.c
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+++ b/kernel/panic.c
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@@ -449,6 +449,7 @@ void panic(const char *fmt, ...)
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* Explicitly flush the kernel log buffer one last time.
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*/
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console_flush_on_panic(CONSOLE_FLUSH_PENDING);
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+ nbcon_atomic_flush_unsafe();
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local_irq_enable();
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for (i = 0; ; i += PANIC_TIMER_STEP) {
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diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
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index 3e999784ba5c..1c01f88d596d 100644
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--- a/kernel/printk/nbcon.c
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+++ b/kernel/printk/nbcon.c
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@@ -1030,8 +1030,9 @@ bool nbcon_atomic_emit_next_record(struct console *con, bool *handover, int cook
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* __nbcon_atomic_flush_all - Flush all nbcon consoles using their
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* write_atomic() callback
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* @stop_seq: Flush up until this record
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+ * @allow_unsafe_takeover: True, to allow unsafe hostile takeovers
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*/
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-static void __nbcon_atomic_flush_all(u64 stop_seq)
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+static void __nbcon_atomic_flush_all(u64 stop_seq, bool allow_unsafe_takeover)
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{
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struct nbcon_write_context wctxt = { };
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struct nbcon_context *ctxt = &ACCESS_PRIVATE(&wctxt, ctxt);
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@@ -1059,6 +1060,7 @@ static void __nbcon_atomic_flush_all(u64 stop_seq)
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memset(ctxt, 0, sizeof(*ctxt));
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ctxt->console = con;
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ctxt->spinwait_max_us = 2000;
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+ ctxt->allow_unsafe_takeover = allow_unsafe_takeover;
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/*
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* Atomic flushing does not use console driver
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@@ -1093,7 +1095,19 @@ static void __nbcon_atomic_flush_all(u64 stop_seq)
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*/
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void nbcon_atomic_flush_all(void)
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{
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- __nbcon_atomic_flush_all(prb_next_reserve_seq(prb));
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+ __nbcon_atomic_flush_all(prb_next_reserve_seq(prb), false);
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+}
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+
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+/**
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+ * nbcon_atomic_flush_unsafe - Flush all nbcon consoles using their
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+ * write_atomic() callback and allowing unsafe hostile takeovers
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+ *
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+ * Flush the backlog up through the currently newest record. Unsafe hostile
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+ * takeovers will be performed, if necessary.
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+ */
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+void nbcon_atomic_flush_unsafe(void)
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+{
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+ __nbcon_atomic_flush_all(prb_next_reserve_seq(prb), true);
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}
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/**
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--
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2.44.0
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