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a450b5b6c0
[ Upstream commit 78cf0eb926cb1abeff2106bae67752e032fe5f3e ]
When update the latest mainline kernel with the following three configs,
the kernel hangs during startup:
(1) CONFIG_FUNCTION_GRAPH_TRACER=y
(2) CONFIG_PREEMPT_TRACER=y
(3) CONFIG_FTRACE_STARTUP_TEST=y
When update the latest mainline kernel with the above two configs (1)
and (2), the kernel starts normally, but it still hangs when execute
the following command:
echo "function_graph" > /sys/kernel/debug/tracing/current_tracer
Without CONFIG_PREEMPT_TRACER=y, the above two kinds of kernel hangs
disappeared, so it seems that CONFIG_PREEMPT_TRACER has some influences
with function_graph tracer at the first glance.
I use ejtag to find out the epc address is related with preempt_enable()
in the file arch/mips/lib/mips-atomic.c, because function tracing can
trace the preempt_{enable,disable} calls that are traced, replace them
with preempt_{enable,disable}_notrace to prevent function tracing from
going into an infinite loop, and then it can fix the kernel hang issue.
By the way, it seems that this commit is a complement and improvement of
commit f93a1a00f2 ("MIPS: Fix crash that occurs when function tracing
is enabled").
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1994, 95, 96, 97, 98, 99, 2003 by Ralf Baechle
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* Copyright (C) 1996 by Paul M. Antoine
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* Copyright (C) 1999 Silicon Graphics
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* Copyright (C) 2000 MIPS Technologies, Inc.
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*/
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#include <asm/irqflags.h>
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#include <asm/hazards.h>
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#include <linux/compiler.h>
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#include <linux/preempt.h>
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#include <linux/export.h>
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#include <linux/stringify.h>
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#if !defined(CONFIG_CPU_MIPSR2) && !defined(CONFIG_CPU_MIPSR6)
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/*
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* For cli() we have to insert nops to make sure that the new value
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* has actually arrived in the status register before the end of this
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* macro.
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* R4000/R4400 need three nops, the R4600 two nops and the R10000 needs
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* no nops at all.
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*/
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/*
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* For TX49, operating only IE bit is not enough.
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*
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* If mfc0 $12 follows store and the mfc0 is last instruction of a
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* page and fetching the next instruction causes TLB miss, the result
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* of the mfc0 might wrongly contain EXL bit.
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*
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* ERT-TX49H2-027, ERT-TX49H3-012, ERT-TX49HL3-006, ERT-TX49H4-008
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*
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* Workaround: mask EXL bit of the result or place a nop before mfc0.
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*/
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notrace void arch_local_irq_disable(void)
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{
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preempt_disable_notrace();
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__asm__ __volatile__(
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" .set push \n"
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" .set noat \n"
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" mfc0 $1,$12 \n"
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" ori $1,0x1f \n"
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" xori $1,0x1f \n"
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" .set noreorder \n"
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" mtc0 $1,$12 \n"
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" " __stringify(__irq_disable_hazard) " \n"
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" .set pop \n"
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: /* no outputs */
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: /* no inputs */
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: "memory");
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preempt_enable_notrace();
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}
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EXPORT_SYMBOL(arch_local_irq_disable);
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notrace unsigned long arch_local_irq_save(void)
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{
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unsigned long flags;
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preempt_disable_notrace();
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__asm__ __volatile__(
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" .set push \n"
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" .set reorder \n"
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" .set noat \n"
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" mfc0 %[flags], $12 \n"
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" ori $1, %[flags], 0x1f \n"
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" xori $1, 0x1f \n"
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" .set noreorder \n"
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" mtc0 $1, $12 \n"
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" " __stringify(__irq_disable_hazard) " \n"
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" .set pop \n"
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: [flags] "=r" (flags)
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: /* no inputs */
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: "memory");
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preempt_enable_notrace();
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return flags;
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}
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EXPORT_SYMBOL(arch_local_irq_save);
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notrace void arch_local_irq_restore(unsigned long flags)
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{
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unsigned long __tmp1;
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preempt_disable_notrace();
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__asm__ __volatile__(
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" .set push \n"
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" .set noreorder \n"
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" .set noat \n"
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" mfc0 $1, $12 \n"
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" andi %[flags], 1 \n"
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" ori $1, 0x1f \n"
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" xori $1, 0x1f \n"
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" or %[flags], $1 \n"
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" mtc0 %[flags], $12 \n"
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" " __stringify(__irq_disable_hazard) " \n"
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" .set pop \n"
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: [flags] "=r" (__tmp1)
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: "0" (flags)
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: "memory");
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preempt_enable_notrace();
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}
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EXPORT_SYMBOL(arch_local_irq_restore);
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#endif /* !CONFIG_CPU_MIPSR2 && !CONFIG_CPU_MIPSR6 */
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