Commit 88485be5 authored by Will Deacon's avatar Will Deacon
Browse files

scs: Move scs_overflow_check() out of architecture code 



There is nothing architecture-specific about scs_overflow_check() as
it's just a trivial wrapper around scs_corrupted().

For parity with task_stack_end_corrupted(), rename scs_corrupted() to
task_scs_end_corrupted() and call it from schedule_debug() when
CONFIG_SCHED_STACK_END_CHECK_is enabled, which better reflects its
purpose as a debug feature to catch inadvertent overflow of the SCS.
Finally, remove the unused scs_overflow_check() function entirely.

This has absolutely no impact on architectures that do not support SCS
(currently arm64 only).

Tested-by: default avatarSami Tolvanen <samitolvanen@google.com>
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 711e8b0d

arch/arm64/include/asm/scs.h

+0 −18
Original line number Diff line number Diff line
@@ -24,24 +24,6 @@ 
	.endm

#endif /* CONFIG_SHADOW_CALL_STACK */



#else /* __ASSEMBLY__ */



#include <linux/scs.h>



#ifdef CONFIG_SHADOW_CALL_STACK



static inline void scs_overflow_check(struct task_struct *tsk)

{

	if (unlikely(scs_corrupted(tsk)))

		panic("corrupted shadow stack detected inside scheduler\n");

}



#else /* CONFIG_SHADOW_CALL_STACK */



static inline void scs_overflow_check(struct task_struct *tsk) {}



#endif /* CONFIG_SHADOW_CALL_STACK */



#endif /* __ASSEMBLY __ */



#endif /* _ASM_SCS_H */

arch/arm64/kernel/process.c

+0 −2
Original line number Diff line number Diff line
@@ -52,7 +52,6 @@ 
#include <asm/mmu_context.h>

#include <asm/processor.h>

#include <asm/pointer_auth.h>

#include <asm/scs.h>

#include <asm/stacktrace.h>



#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
@@ -516,7 +515,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, 
	entry_task_switch(next);

	uao_thread_switch(next);

	ssbs_thread_switch(next);

	scs_overflow_check(next);



	/*

	 * Complete any pending TLB or cache maintenance on this CPU in case

arch/arm64/kernel/scs.c

+1 −1
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ 
 */



#include <linux/percpu.h>

#include <asm/scs.h>

#include <linux/scs.h>



/* Allocate a static per-CPU shadow stack */

#define DEFINE_SCS(name)						\

include/linux/scs.h

+2 −2
Original line number Diff line number Diff line
@@ -47,7 +47,7 @@ static inline unsigned long *__scs_magic(void *s) 
	return (unsigned long *)(s + SCS_SIZE) - 1;

}



static inline bool scs_corrupted(struct task_struct *tsk)

static inline bool task_scs_end_corrupted(struct task_struct *tsk)

{

	unsigned long *magic = __scs_magic(task_scs(tsk));

	unsigned long sz = task_scs_sp(tsk) - task_scs(tsk);
@@ -60,8 +60,8 @@ static inline bool scs_corrupted(struct task_struct *tsk) 
static inline void scs_init(void) {}

static inline void scs_task_reset(struct task_struct *tsk) {}

static inline int scs_prepare(struct task_struct *tsk, int node) { return 0; }

static inline bool scs_corrupted(struct task_struct *tsk) { return false; }

static inline void scs_release(struct task_struct *tsk) {}

static inline bool task_scs_end_corrupted(struct task_struct *tsk) { return false; }



#endif /* CONFIG_SHADOW_CALL_STACK */

kernel/sched/core.c

+3 −0
Original line number Diff line number Diff line
@@ -3878,6 +3878,9 @@ static inline void schedule_debug(struct task_struct *prev, bool preempt) 
#ifdef CONFIG_SCHED_STACK_END_CHECK

	if (task_stack_end_corrupted(prev))

		panic("corrupted stack end detected inside scheduler\n");



	if (task_scs_end_corrupted(prev))

		panic("corrupted shadow stack detected inside scheduler\n");

#endif



#ifdef CONFIG_DEBUG_ATOMIC_SLEEP

CRA Git | Maintained and supported by SUSTech CRA and CCSE