Commit c6089061 authored by Russell King's avatar Russell King
Browse files

ARM: probes: avoid adding kprobes to sensitive kernel-entry/exit code 



Avoid adding kprobes to any of the kernel entry/exit or startup
assembly code, or code in the identity-mapped region.  This code does
not conform to the standard C conventions, which means that the
expectations of the kprobes code is not forfilled.

Placing kprobes at some of these locations results in the kernel trying
to return to userspace addresses while retaining the CPU in kernel mode.

Tested-by: default avatarNaresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent 75fea300

arch/arm/include/asm/exception.h

+1 −2
Original line number Diff line number Diff line
@@ -10,11 +10,10 @@ 


#include <linux/interrupt.h>



#define __exception	__attribute__((section(".exception.text")))

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

#define __exception_irq_entry	__irq_entry

#else

#define __exception_irq_entry	__exception

#define __exception_irq_entry

#endif



#endif /* __ASM_ARM_EXCEPTION_H */

arch/arm/include/asm/sections.h

+21 −0
Original line number Diff line number Diff line
@@ -6,4 +6,25 @@ 


extern char _exiprom[];



extern char __idmap_text_start[];

extern char __idmap_text_end[];

extern char __entry_text_start[];

extern char __entry_text_end[];

extern char __hyp_idmap_text_start[];

extern char __hyp_idmap_text_end[];



static inline bool in_entry_text(unsigned long addr)

{

	return memory_contains(__entry_text_start, __entry_text_end,

			       (void *)addr, 1);

}



static inline bool in_idmap_text(unsigned long addr)

{

	void *a = (void *)addr;

	return memory_contains(__idmap_text_start, __idmap_text_end, a, 1) ||

	       memory_contains(__hyp_idmap_text_start, __hyp_idmap_text_end,

			       a, 1);

}



#endif	/* _ASM_ARM_SECTIONS_H */

arch/arm/include/asm/traps.h

+0 −12
Original line number Diff line number Diff line
@@ -28,18 +28,6 @@ static inline int __in_irqentry_text(unsigned long ptr) 
	       ptr < (unsigned long)&__irqentry_text_end;

}



static inline int in_exception_text(unsigned long ptr)

{

	extern char __exception_text_start[];

	extern char __exception_text_end[];

	int in;



	in = ptr >= (unsigned long)&__exception_text_start &&

	     ptr < (unsigned long)&__exception_text_end;



	return in ? : __in_irqentry_text(ptr);

}



extern void __init early_trap_init(void *);

extern void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame);

extern void ptrace_break(struct task_struct *tsk, struct pt_regs *regs);

arch/arm/kernel/entry-armv.S

+1 −5
Original line number Diff line number Diff line
@@ -82,11 +82,7 @@ 
#endif

	.endm



#ifdef CONFIG_KPROBES

	.section	.kprobes.text,"ax",%progbits

#else

	.text

#endif

	.section	.entry.text,"ax",%progbits



/*

 * Invalid mode handlers

arch/arm/kernel/entry-common.S

+1 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ saved_pc .req lr 
#define TRACE(x...)

#endif



	.section .entry.text,"ax",%progbits

	.align	5

#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING))

/*

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