Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b99610fb authored by Matt Fleming's avatar Matt Fleming Committed by Paul Mundt
Browse files

sh: Provide diagnostic kernel stack checks 



Enable kernel stack checking code in both the dynamic ftrace and mcount
code paths. Check the stack to see if it's overflowing and make sure
that the stack pointer contains an address that's either in init_stack
or after the bss.

Signed-off-by: default avatarMatt Fleming <matt@console-pimps.org>
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent c652d780

arch/sh/Kconfig.debug

+11 −0
Original line number Diff line number Diff line
@@ -123,4 +123,15 @@ config SH64_SR_WATCH 
	bool "Debug: set SR.WATCH to enable hardware watchpoints and trace"

	depends on SUPERH64



config STACK_DEBUG

	bool "Enable diagnostic checks of the kernel stack"

	depends on FUNCTION_TRACER

	select DEBUG_STACKOVERFLOW

	default n

	help

	  This option allows checks to be performed on the kernel stack

	  at runtime. Saying Y here will add overhead to every function

	  call and will therefore incur a major performance hit. Most

	  users should say N.



endmenu

arch/sh/kernel/asm-offsets.c

+1 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ int main(void) 
	DEFINE(TI_CPU,		offsetof(struct thread_info, cpu));

	DEFINE(TI_PRE_COUNT,	offsetof(struct thread_info, preempt_count));

	DEFINE(TI_RESTART_BLOCK,offsetof(struct thread_info, restart_block));

	DEFINE(TI_SIZE,		sizeof(struct thread_info));



#ifdef CONFIG_HIBERNATION

	DEFINE(PBE_ADDRESS, offsetof(struct pbe, address));

arch/sh/lib/mcount.S

+85 −0
Original line number Diff line number Diff line
@@ -9,6 +9,8 @@ 
 * for more details.

 */

#include <asm/ftrace.h>

#include <asm/thread_info.h>

#include <asm/asm-offsets.h>



#define MCOUNT_ENTER()		\

	mov.l	r4, @-r15;	\
@@ -28,6 +30,55 @@ 
	rts;			\

	 mov.l	@r15+, r4



#ifdef CONFIG_STACK_DEBUG

/*

 * Perform diagnostic checks on the state of the kernel stack.

 *

 * Check for stack overflow. If there is less than 1KB free

 * then it has overflowed.

 *

 * Make sure the stack pointer contains a valid address. Valid

 * addresses for kernel stacks are anywhere after the bss

 * (after _ebss) and anywhere in init_thread_union (init_stack).

 */

#define STACK_CHECK()					\

	mov	#(THREAD_SIZE >> 10), r0;		\

	shll8	r0;					\

	shll2	r0;					\

							\

	/* r1 = sp & (THREAD_SIZE - 1) */		\

	mov	#-1, r1;				\

	add	r0, r1;					\

	and	r15, r1;				\

							\

	mov	#TI_SIZE, r3;				\

	mov	#(STACK_WARN >> 8), r2;			\

	shll8	r2;					\

	add	r3, r2;					\

							\

	/* Is the stack overflowing? */			\

	cmp/hi	r2, r1;					\

	bf	stack_panic;				\

							\

	/* If sp > _ebss then we're OK. */		\

	mov.l	.L_ebss, r1;				\

	cmp/hi	r1, r15;				\

	bt	1f;					\

							\

	/* If sp < init_stack, we're not OK. */		\

	mov.l	.L_init_thread_union, r1;		\

	cmp/hs	r1, r15;				\

	bf	stack_panic;				\

							\

	/* If sp > init_stack && sp < _ebss, not OK. */	\

	add	r0, r1;					\

	cmp/hs	r1, r15;				\

	bt	stack_panic;				\

1:

#else

#define STACK_CHECK()

#endif /* CONFIG_STACK_DEBUG */



	.align 2

	.globl	_mcount

	.type	_mcount,@function
@@ -41,6 +92,8 @@ mcount: 
	tst	r0, r0

	bf	ftrace_stub

#endif

	STACK_CHECK()



	MCOUNT_ENTER()



#ifdef CONFIG_DYNAMIC_FTRACE
@@ -73,6 +126,8 @@ ftrace_caller: 
	tst	r0, r0

	bf	ftrace_stub



	STACK_CHECK()



	MCOUNT_ENTER()



	.globl ftrace_call
@@ -100,6 +155,36 @@ ftrace_stub: 
	rts

	 nop



#ifdef CONFIG_STACK_DEBUG

	.globl	stack_panic

stack_panic:

	mov.l	.Ldump_stack, r0

	jsr	@r0

	 nop



	mov.l	.Lpanic, r0

	jsr	@r0

	 mov.l	.Lpanic_s, r4



	rts

	 nop



	.align 2

.Lfunction_trace_stop:

	.long	function_trace_stop

.L_ebss:

	.long	_ebss

.L_init_thread_union:

	.long	init_thread_union

.Lpanic:

	.long	panic

.Lpanic_s:

	.long	.Lpanic_str

.Ldump_stack:

	.long	dump_stack



	.section	.rodata

	.align 2

.Lpanic_str:

	.string "Stack error"

#endif /* CONFIG_STACK_DEBUG */