x86/entry: Unbreak __irqentry_text_start/end magic
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>
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 8ecaeee..d2a00c9 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -478,10 +478,19 @@
/*
* Include the defines which emit the idt entries which are shared
- * shared between 32 and 64 bit.
+ * shared between 32 and 64 bit and emit the __irqentry_text_* markers
+ * so the stacktrace boundary checks work.
*/
+ .align 16
+ .globl __irqentry_text_start
+__irqentry_text_start:
+
#include <asm/idtentry.h>
+ .align 16
+ .globl __irqentry_text_end
+__irqentry_text_end:
+
SYM_CODE_START_LOCAL(common_interrupt_return)
SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL)
#ifdef CONFIG_DEBUG_ENTRY
