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x86/entry: Unbreak __irqentry_text_start/end magic

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The entry rework moved interrupt entry code from the irqentry to the
noinstr section which made the irqentry section empty.

This breaks boundary checks which rely on the __irqentry_text_start/end
markers to find out whether a function in a stack trace is
interrupt/exception entry code. This affects the function graph tracer and
filter_irq_stacks().

As the IDT entry points are all sequentialy emitted this is rather simple
to unbreak by injecting __irqentry_text_start/end as global labels.

To make this work correctly:

  - Remove the IRQENTRY_TEXT section from the x86 linker script
  - Define __irqentry so it breaks the build if it's used
  - Adjust the entry mirroring in PTI
  - Remove the redundant kprobes and unwinder bound checks

Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner
2020-06-10 08:37:01 +02:00
parent 2823e83a3d
commit f0178fc01f
9 changed files with 36 additions and 25 deletions
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8
include/linux/interrupt.h
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@@ -760,8 +760,10 @@ extern int arch_early_irq_init(void);
/*
* We want to know which function is an entrypoint of a hardirq or a softirq.
*/
#define __irq_entry __attribute__((__section__(".irqentry.text")))
#define __softirq_entry \
__attribute__((__section__(".softirqentry.text")))
#ifndef __irq_entry
# define __irq_entry __attribute__((__section__(".irqentry.text")))
#endif
#define __softirq_entry __attribute__((__section__(".softirqentry.text")))
#endif