add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/kernel/printk/printk_safe.c
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@@ -1,27 +1,17 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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  * printk_safe.c - Safe printk for printk-deadlock-prone contexts
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- *
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- * This program is free software; you can redistribute it and/or
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- * modify it under the terms of the GNU General Public License
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- * as published by the Free Software Foundation; either version 2
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- * of the License, or (at your option) any later version.
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- *
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- * This program is distributed in the hope that it will be useful,
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- * but WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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- * GNU General Public License for more details.
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- *
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- * You should have received a copy of the GNU General Public License
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- * along with this program; if not, see <http://www.gnu.org/licenses/>.
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  */
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 #include <linux/preempt.h>
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 #include <linux/spinlock.h>
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 #include <linux/debug_locks.h>
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+#include <linux/kdb.h>
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 #include <linux/smp.h>
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 #include <linux/cpumask.h>
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 #include <linux/irq_work.h>
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 #include <linux/printk.h>
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+#include <linux/kprobes.h>
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15
 
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 #include "internal.h"
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@@ -32,7 +22,7 @@
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  * is later flushed into the main ring buffer via IRQ work.
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  *
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  * The alternative implementation is chosen transparently
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- * by examinig current printk() context mask stored in @printk_context
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+ * by examining current printk() context mask stored in @printk_context
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  * per-CPU variable.
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  *
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  * The implementation allows to flush the strings also from another CPU.
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@@ -313,14 +303,14 @@
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 	return printk_safe_log_store(s, fmt, args);
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 }
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-void notrace printk_nmi_enter(void)
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+void noinstr printk_nmi_enter(void)
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 {
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-	this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK);
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+	this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET);
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 }
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-void notrace printk_nmi_exit(void)
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+void noinstr printk_nmi_exit(void)
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 {
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-	this_cpu_and(printk_context, ~PRINTK_NMI_CONTEXT_MASK);
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+	this_cpu_sub(printk_context, PRINTK_NMI_CONTEXT_OFFSET);
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 }
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 /*
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@@ -379,6 +369,12 @@
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 __printf(1, 0) int vprintk_func(const char *fmt, va_list args)
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 {
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+#ifdef CONFIG_KGDB_KDB
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+	/* Allow to pass printk() to kdb but avoid a recursion. */
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+	if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0))
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+		return vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
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+#endif
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+
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 	/*
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 	 * Try to use the main logbuf even in NMI. But avoid calling console
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 	 * drivers that might have their own locks.
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@@ -387,7 +383,7 @@
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 	    raw_spin_trylock(&logbuf_lock)) {
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 		int len;
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-		len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
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+		len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
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 		raw_spin_unlock(&logbuf_lock);
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 		defer_console_output();
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 		return len;