linux/kernel/locking/irqflag-debug.c

// SPDX-License-Identifier: GPL-2.0-only

#include <linux/bug.h>
#include <linux/export.h>
#include <linux/irqflags.h>

noinstr void warn_bogus_irq_restore(void)
{
	instrumentation_begin();
	WARN_ONCE(1, "raw_local_irq_restore() called with IRQs enabled\n");
	instrumentation_end();
}
EXPORT_SYMBOL(warn_bogus_irq_restore);
lockdep: report broken irq restoration We generally expect local_irq_save() and local_irq_restore() to be paired and sanely nested, and so local_irq_restore() expects to be called with irqs disabled. Thus, within local_irq_restore() we only trace irq flag changes when unmasking irqs. This means that a sequence such as: \| local_irq_disable(); \| local_irq_save(flags); \| local_irq_enable(); \| local_irq_restore(flags); ... is liable to break things, as the local_irq_restore() would mask irqs without tracing this change. Similar problems may exist for architectures whose arch_irq_restore() function depends on being called with irqs disabled. We don't consider such sequences to be a good idea, so let's define those as forbidden, and add tooling to detect such broken cases. This patch adds debug code to WARN() when raw_local_irq_restore() is called with irqs enabled. As raw_local_irq_restore() is expected to pair with raw_local_irq_save(), it should never be called with irqs enabled. To avoid the possibility of circular header dependencies between irqflags.h and bug.h, the warning is handled in a separate C file. The new code is all conditional on a new CONFIG_DEBUG_IRQFLAGS symbol which is independent of CONFIG_TRACE_IRQFLAGS. As noted above such cases will confuse lockdep, so CONFIG_DEBUG_LOCKDEP now selects CONFIG_DEBUG_IRQFLAGS. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210111153707.10071-1-mark.rutland@arm.com 2021-01-11 18:37:07 +03:00			`// SPDX-License-Identifier: GPL-2.0-only`

			`#include <linux/bug.h>`
			`#include <linux/export.h>`
			`#include <linux/irqflags.h>`

lockdep: Noinstr annotate warn_bogus_irq_restore() vmlinux.o: warning: objtool: lock_is_held_type()+0x107: call to warn_bogus_irq_restore() leaves .noinstr.text section As per the general rule that WARNs are allowed to violate noinstr to get out, annotate it away. Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Link: https://lkml.kernel.org/r/YCKyYg53mMp4E7YI@hirez.programming.kicks-ass.net 2021-02-09 11:30:03 +03:00			`noinstr void warn_bogus_irq_restore(void)`
lockdep: report broken irq restoration We generally expect local_irq_save() and local_irq_restore() to be paired and sanely nested, and so local_irq_restore() expects to be called with irqs disabled. Thus, within local_irq_restore() we only trace irq flag changes when unmasking irqs. This means that a sequence such as: \| local_irq_disable(); \| local_irq_save(flags); \| local_irq_enable(); \| local_irq_restore(flags); ... is liable to break things, as the local_irq_restore() would mask irqs without tracing this change. Similar problems may exist for architectures whose arch_irq_restore() function depends on being called with irqs disabled. We don't consider such sequences to be a good idea, so let's define those as forbidden, and add tooling to detect such broken cases. This patch adds debug code to WARN() when raw_local_irq_restore() is called with irqs enabled. As raw_local_irq_restore() is expected to pair with raw_local_irq_save(), it should never be called with irqs enabled. To avoid the possibility of circular header dependencies between irqflags.h and bug.h, the warning is handled in a separate C file. The new code is all conditional on a new CONFIG_DEBUG_IRQFLAGS symbol which is independent of CONFIG_TRACE_IRQFLAGS. As noted above such cases will confuse lockdep, so CONFIG_DEBUG_LOCKDEP now selects CONFIG_DEBUG_IRQFLAGS. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210111153707.10071-1-mark.rutland@arm.com 2021-01-11 18:37:07 +03:00			`{`
lockdep: Noinstr annotate warn_bogus_irq_restore() vmlinux.o: warning: objtool: lock_is_held_type()+0x107: call to warn_bogus_irq_restore() leaves .noinstr.text section As per the general rule that WARNs are allowed to violate noinstr to get out, annotate it away. Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Link: https://lkml.kernel.org/r/YCKyYg53mMp4E7YI@hirez.programming.kicks-ass.net 2021-02-09 11:30:03 +03:00			`instrumentation_begin();`
lockdep: report broken irq restoration We generally expect local_irq_save() and local_irq_restore() to be paired and sanely nested, and so local_irq_restore() expects to be called with irqs disabled. Thus, within local_irq_restore() we only trace irq flag changes when unmasking irqs. This means that a sequence such as: \| local_irq_disable(); \| local_irq_save(flags); \| local_irq_enable(); \| local_irq_restore(flags); ... is liable to break things, as the local_irq_restore() would mask irqs without tracing this change. Similar problems may exist for architectures whose arch_irq_restore() function depends on being called with irqs disabled. We don't consider such sequences to be a good idea, so let's define those as forbidden, and add tooling to detect such broken cases. This patch adds debug code to WARN() when raw_local_irq_restore() is called with irqs enabled. As raw_local_irq_restore() is expected to pair with raw_local_irq_save(), it should never be called with irqs enabled. To avoid the possibility of circular header dependencies between irqflags.h and bug.h, the warning is handled in a separate C file. The new code is all conditional on a new CONFIG_DEBUG_IRQFLAGS symbol which is independent of CONFIG_TRACE_IRQFLAGS. As noted above such cases will confuse lockdep, so CONFIG_DEBUG_LOCKDEP now selects CONFIG_DEBUG_IRQFLAGS. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210111153707.10071-1-mark.rutland@arm.com 2021-01-11 18:37:07 +03:00			`WARN_ONCE(1, "raw_local_irq_restore() called with IRQs enabled\n");`
lockdep: Noinstr annotate warn_bogus_irq_restore() vmlinux.o: warning: objtool: lock_is_held_type()+0x107: call to warn_bogus_irq_restore() leaves .noinstr.text section As per the general rule that WARNs are allowed to violate noinstr to get out, annotate it away. Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Link: https://lkml.kernel.org/r/YCKyYg53mMp4E7YI@hirez.programming.kicks-ass.net 2021-02-09 11:30:03 +03:00			`instrumentation_end();`
lockdep: report broken irq restoration We generally expect local_irq_save() and local_irq_restore() to be paired and sanely nested, and so local_irq_restore() expects to be called with irqs disabled. Thus, within local_irq_restore() we only trace irq flag changes when unmasking irqs. This means that a sequence such as: \| local_irq_disable(); \| local_irq_save(flags); \| local_irq_enable(); \| local_irq_restore(flags); ... is liable to break things, as the local_irq_restore() would mask irqs without tracing this change. Similar problems may exist for architectures whose arch_irq_restore() function depends on being called with irqs disabled. We don't consider such sequences to be a good idea, so let's define those as forbidden, and add tooling to detect such broken cases. This patch adds debug code to WARN() when raw_local_irq_restore() is called with irqs enabled. As raw_local_irq_restore() is expected to pair with raw_local_irq_save(), it should never be called with irqs enabled. To avoid the possibility of circular header dependencies between irqflags.h and bug.h, the warning is handled in a separate C file. The new code is all conditional on a new CONFIG_DEBUG_IRQFLAGS symbol which is independent of CONFIG_TRACE_IRQFLAGS. As noted above such cases will confuse lockdep, so CONFIG_DEBUG_LOCKDEP now selects CONFIG_DEBUG_IRQFLAGS. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210111153707.10071-1-mark.rutland@arm.com 2021-01-11 18:37:07 +03:00			`}`
			`EXPORT_SYMBOL(warn_bogus_irq_restore);`