Commit 6b27edd7 authored by Joerg Roedel's avatar Joerg Roedel Committed by Borislav Petkov
Browse files

x86/dumpstack/64: Add noinstr version of get_stack_info() 



The get_stack_info() functionality is needed in the entry code for the
#VC exception handler. Provide a version of it in the .text.noinstr
section which can be called safely from there.

Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-45-joro@8bytes.org
parent 315562c9

arch/x86/include/asm/stacktrace.h

+2 −0
Original line number Diff line number Diff line
@@ -35,6 +35,8 @@ bool in_entry_stack(unsigned long *stack, struct stack_info *info); 


int get_stack_info(unsigned long *stack, struct task_struct *task,

		   struct stack_info *info, unsigned long *visit_mask);

bool get_stack_info_noinstr(unsigned long *stack, struct task_struct *task,

			    struct stack_info *info);



const char *stack_type_name(enum stack_type type);

arch/x86/kernel/dumpstack.c

+4 −3
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ static int die_counter; 


static struct pt_regs exec_summary_regs;



bool in_task_stack(unsigned long *stack, struct task_struct *task,

bool noinstr in_task_stack(unsigned long *stack, struct task_struct *task,

			   struct stack_info *info)

{

	unsigned long *begin = task_stack_page(task);
@@ -46,7 +46,8 @@ bool in_task_stack(unsigned long *stack, struct task_struct *task, 
	return true;

}



bool in_entry_stack(unsigned long *stack, struct stack_info *info)

/* Called from get_stack_info_noinstr - so must be noinstr too */

bool noinstr in_entry_stack(unsigned long *stack, struct stack_info *info)

{

	struct entry_stack *ss = cpu_entry_stack(smp_processor_id());

arch/x86/kernel/dumpstack_64.c

+22 −16
Original line number Diff line number Diff line
@@ -85,7 +85,7 @@ struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = { 
	EPAGERANGE(VC2),

};



static bool in_exception_stack(unsigned long *stack, struct stack_info *info)

static __always_inline bool in_exception_stack(unsigned long *stack, struct stack_info *info)

{

	unsigned long begin, end, stk = (unsigned long)stack;

	const struct estack_pages *ep;
@@ -126,7 +126,7 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info) 
	return true;

}



static bool in_irq_stack(unsigned long *stack, struct stack_info *info)

static __always_inline bool in_irq_stack(unsigned long *stack, struct stack_info *info)

{

	unsigned long *end   = (unsigned long *)this_cpu_read(hardirq_stack_ptr);

	unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
@@ -151,32 +151,38 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info) 
	return true;

}



int get_stack_info(unsigned long *stack, struct task_struct *task,

		   struct stack_info *info, unsigned long *visit_mask)

bool noinstr get_stack_info_noinstr(unsigned long *stack, struct task_struct *task,

				    struct stack_info *info)

{

	if (!stack)

		goto unknown;



	task = task ? : current;



	if (in_task_stack(stack, task, info))

		goto recursion_check;

		return true;



	if (task != current)

		goto unknown;

		return false;



	if (in_exception_stack(stack, info))

		goto recursion_check;

		return true;



	if (in_irq_stack(stack, info))

		goto recursion_check;

		return true;



	if (in_entry_stack(stack, info))

		goto recursion_check;

		return true;



	return false;

}



int get_stack_info(unsigned long *stack, struct task_struct *task,

		   struct stack_info *info, unsigned long *visit_mask)

{

	task = task ? : current;



	if (!stack)

		goto unknown;



	if (!get_stack_info_noinstr(stack, task, info))

		goto unknown;



recursion_check:

	/*

	 * Make sure we don't iterate through any given stack more than once.

	 * If it comes up a second time then there's something wrong going on:

arch/x86/mm/cpu_entry_area.c

+2 −1
Original line number Diff line number Diff line
@@ -21,7 +21,8 @@ DEFINE_PER_CPU(struct cea_exception_stacks*, cea_exception_stacks); 
DECLARE_PER_CPU_PAGE_ALIGNED(struct doublefault_stack, doublefault_stack);

#endif



struct cpu_entry_area *get_cpu_entry_area(int cpu)

/* Is called from entry code, so must be noinstr */

noinstr struct cpu_entry_area *get_cpu_entry_area(int cpu)

{

	unsigned long va = CPU_ENTRY_AREA_PER_CPU + cpu * CPU_ENTRY_AREA_SIZE;

	BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE != 0);