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Commit 78c98f90 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/unwind: introduce stack unwind API 



Rework the dump_trace() stack unwinder interface to support different
unwinding algorithms. The new interface looks like this:

	struct unwind_state state;
	unwind_for_each_frame(&state, task, regs, start_stack)
		do_something(state.sp, state.ip, state.reliable);

The unwind_bc.c file contains the implementation for the classic
back-chain unwinder.

One positive side effect of the new code is it now handles ftraced
functions gracefully. It prints the real name of the return function
instead of 'return_to_handler'.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 1c705ad5

arch/s390/include/asm/processor.h

+0 −72
Original line number Diff line number Diff line
@@ -156,25 +156,6 @@ struct thread_struct { 


typedef struct thread_struct thread_struct;



/*

 * Stack layout of a C stack frame.

 */

#ifndef __PACK_STACK

struct stack_frame {

	unsigned long back_chain;

	unsigned long empty1[5];

	unsigned long gprs[10];

	unsigned int  empty2[8];

};

#else

struct stack_frame {

	unsigned long empty1[5];

	unsigned int  empty2[8];

	unsigned long gprs[10];

	unsigned long back_chain;

};

#endif



#define ARCH_MIN_TASKALIGN	8



#define INIT_THREAD {							\
@@ -206,11 +187,7 @@ struct mm_struct; 
struct seq_file;

struct pt_regs;



typedef int (*dump_trace_func_t)(void *data, unsigned long address, int reliable);

void dump_trace(dump_trace_func_t func, void *data,

		struct task_struct *task, unsigned long sp);

void show_registers(struct pt_regs *regs);



void show_cacheinfo(struct seq_file *m);



/* Free all resources held by a thread. */
@@ -244,55 +221,6 @@ static __no_kasan_or_inline unsigned short stap(void) 
	return cpu_address;

}



#define CALL_ARGS_0()							\

	register unsigned long r2 asm("2")

#define CALL_ARGS_1(arg1)						\

	register unsigned long r2 asm("2") = (unsigned long)(arg1)

#define CALL_ARGS_2(arg1, arg2)						\

	CALL_ARGS_1(arg1);						\

	register unsigned long r3 asm("3") = (unsigned long)(arg2)

#define CALL_ARGS_3(arg1, arg2, arg3)					\

	CALL_ARGS_2(arg1, arg2);					\

	register unsigned long r4 asm("4") = (unsigned long)(arg3)

#define CALL_ARGS_4(arg1, arg2, arg3, arg4)				\

	CALL_ARGS_3(arg1, arg2, arg3);					\

	register unsigned long r4 asm("5") = (unsigned long)(arg4)

#define CALL_ARGS_5(arg1, arg2, arg3, arg4, arg5)			\

	CALL_ARGS_4(arg1, arg2, arg3, arg4);				\

	register unsigned long r4 asm("6") = (unsigned long)(arg5)



#define CALL_FMT_0 "=&d" (r2) :

#define CALL_FMT_1 "+&d" (r2) :

#define CALL_FMT_2 CALL_FMT_1 "d" (r3),

#define CALL_FMT_3 CALL_FMT_2 "d" (r4),

#define CALL_FMT_4 CALL_FMT_3 "d" (r5),

#define CALL_FMT_5 CALL_FMT_4 "d" (r6),



#define CALL_CLOBBER_5 "0", "1", "14", "cc", "memory"

#define CALL_CLOBBER_4 CALL_CLOBBER_5

#define CALL_CLOBBER_3 CALL_CLOBBER_4, "5"

#define CALL_CLOBBER_2 CALL_CLOBBER_3, "4"

#define CALL_CLOBBER_1 CALL_CLOBBER_2, "3"

#define CALL_CLOBBER_0 CALL_CLOBBER_1



#define CALL_ON_STACK(fn, stack, nr, args...)				\

({									\

	CALL_ARGS_##nr(args);						\

	unsigned long prev;						\

									\

	asm volatile(							\

		"	la	%[_prev],0(15)\n"			\

		"	la	15,0(%[_stack])\n"			\

		"	stg	%[_prev],%[_bc](15)\n"			\

		"	brasl	14,%[_fn]\n"				\

		"	la	15,0(%[_prev])\n"			\

		: [_prev] "=&a" (prev), CALL_FMT_##nr			\

		  [_stack] "a" (stack),					\

		  [_bc] "i" (offsetof(struct stack_frame, back_chain)),	\

		  [_fn] "X" (fn) : CALL_CLOBBER_##nr);			\

	r2;								\

})



/*

 * Give up the time slice of the virtual PU.

 */

arch/s390/include/asm/stacktrace.h

0 → 100644
+114 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _ASM_S390_STACKTRACE_H

#define _ASM_S390_STACKTRACE_H



#include <linux/uaccess.h>

#include <linux/ptrace.h>

#include <asm/switch_to.h>



enum stack_type {

	STACK_TYPE_UNKNOWN,

	STACK_TYPE_TASK,

	STACK_TYPE_IRQ,

	STACK_TYPE_NODAT,

	STACK_TYPE_RESTART,

};



struct stack_info {

	enum stack_type type;

	unsigned long begin, end;

};



const char *stack_type_name(enum stack_type type);

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

		   struct stack_info *info, unsigned long *visit_mask);



static inline bool on_stack(struct stack_info *info,

			    unsigned long addr, size_t len)

{

	if (info->type == STACK_TYPE_UNKNOWN)

		return false;

	if (addr + len < addr)

		return false;

	return addr >= info->begin && addr + len < info->end;

}



static inline unsigned long get_stack_pointer(struct task_struct *task,

					      struct pt_regs *regs)

{

	if (regs)

		return (unsigned long) kernel_stack_pointer(regs);

	if (task == current)

		return current_stack_pointer();

	return (unsigned long) task->thread.ksp;

}



/*

 * Stack layout of a C stack frame.

 */

#ifndef __PACK_STACK

struct stack_frame {

	unsigned long back_chain;

	unsigned long empty1[5];

	unsigned long gprs[10];

	unsigned int  empty2[8];

};

#else

struct stack_frame {

	unsigned long empty1[5];

	unsigned int  empty2[8];

	unsigned long gprs[10];

	unsigned long back_chain;

};

#endif



#define CALL_ARGS_0()							\

	register unsigned long r2 asm("2")

#define CALL_ARGS_1(arg1)						\

	register unsigned long r2 asm("2") = (unsigned long)(arg1)

#define CALL_ARGS_2(arg1, arg2)						\

	CALL_ARGS_1(arg1);						\

	register unsigned long r3 asm("3") = (unsigned long)(arg2)

#define CALL_ARGS_3(arg1, arg2, arg3)					\

	CALL_ARGS_2(arg1, arg2);					\

	register unsigned long r4 asm("4") = (unsigned long)(arg3)

#define CALL_ARGS_4(arg1, arg2, arg3, arg4)				\

	CALL_ARGS_3(arg1, arg2, arg3);					\

	register unsigned long r4 asm("5") = (unsigned long)(arg4)

#define CALL_ARGS_5(arg1, arg2, arg3, arg4, arg5)			\

	CALL_ARGS_4(arg1, arg2, arg3, arg4);				\

	register unsigned long r4 asm("6") = (unsigned long)(arg5)



#define CALL_FMT_0 "=&d" (r2) :

#define CALL_FMT_1 "+&d" (r2) :

#define CALL_FMT_2 CALL_FMT_1 "d" (r3),

#define CALL_FMT_3 CALL_FMT_2 "d" (r4),

#define CALL_FMT_4 CALL_FMT_3 "d" (r5),

#define CALL_FMT_5 CALL_FMT_4 "d" (r6),



#define CALL_CLOBBER_5 "0", "1", "14", "cc", "memory"

#define CALL_CLOBBER_4 CALL_CLOBBER_5

#define CALL_CLOBBER_3 CALL_CLOBBER_4, "5"

#define CALL_CLOBBER_2 CALL_CLOBBER_3, "4"

#define CALL_CLOBBER_1 CALL_CLOBBER_2, "3"

#define CALL_CLOBBER_0 CALL_CLOBBER_1



#define CALL_ON_STACK(fn, stack, nr, args...)				\

({									\

	CALL_ARGS_##nr(args);						\

	unsigned long prev;						\

									\

	asm volatile(							\

		"	la	%[_prev],0(15)\n"			\

		"	la	15,0(%[_stack])\n"			\

		"	stg	%[_prev],%[_bc](15)\n"			\

		"	brasl	14,%[_fn]\n"				\

		"	la	15,0(%[_prev])\n"			\

		: [_prev] "=&a" (prev), CALL_FMT_##nr			\

		  [_stack] "a" (stack),					\

		  [_bc] "i" (offsetof(struct stack_frame, back_chain)),	\

		  [_fn] "X" (fn) : CALL_CLOBBER_##nr);			\

	r2;								\

})



#endif /* _ASM_S390_STACKTRACE_H */

arch/s390/include/asm/unwind.h

0 → 100644
+101 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _ASM_S390_UNWIND_H

#define _ASM_S390_UNWIND_H



#include <linux/sched.h>

#include <linux/ftrace.h>

#include <asm/ptrace.h>

#include <asm/stacktrace.h>



/*

 * To use the stack unwinder it has to be initialized with unwind_start.

 * There four combinations for task and regs:

 * 1) task==NULL, regs==NULL: the unwind starts for the task that is currently

 *    running, sp/ip picked up from the CPU registers

 * 2) task==NULL, regs!=NULL: the unwind starts from the sp/ip found in

 *    the struct pt_regs of an interrupt frame for the current task

 * 3) task!=NULL, regs==NULL: the unwind starts for an inactive task with

 *    the sp picked up from task->thread.ksp and the ip picked up from the

 *    return address stored by __switch_to

 * 4) task!=NULL, regs!=NULL: the sp/ip are picked up from the interrupt

 *    frame 'regs' of a inactive task

 * If 'first_frame' is not zero unwind_start skips unwind frames until it

 * reaches the specified stack pointer.

 * The end of the unwinding is indicated with unwind_done, this can be true

 * right after unwind_start, e.g. with first_frame!=0 that can not be found.

 * unwind_next_frame skips to the next frame.

 * Once the unwind is completed unwind_error() can be used to check if there

 * has been a situation where the unwinder could not correctly understand

 * the tasks call chain.

 */



struct unwind_state {

	struct stack_info stack_info;

	unsigned long stack_mask;

	struct task_struct *task;

	struct pt_regs *regs;

	unsigned long sp, ip;

	int graph_idx;

	bool reliable;

	bool error;

};



void __unwind_start(struct unwind_state *state, struct task_struct *task,

		    struct pt_regs *regs, unsigned long first_frame);

bool unwind_next_frame(struct unwind_state *state);

unsigned long unwind_get_return_address(struct unwind_state *state);



static inline bool unwind_done(struct unwind_state *state)

{

	return state->stack_info.type == STACK_TYPE_UNKNOWN;

}



static inline bool unwind_error(struct unwind_state *state)

{

	return state->error;

}



static inline void unwind_start(struct unwind_state *state,

				struct task_struct *task,

				struct pt_regs *regs,

				unsigned long sp)

{

	sp = sp ? : get_stack_pointer(task, regs);

	__unwind_start(state, task, regs, sp);

}



static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)

{

	return unwind_done(state) ? NULL : state->regs;

}



#define unwind_for_each_frame(state, task, regs, first_frame)	\

	for (unwind_start(state, task, regs, first_frame);	\

	     !unwind_done(state);				\

	     unwind_next_frame(state))



static inline void unwind_init(void) {}

static inline void unwind_module_init(struct module *mod, void *orc_ip,

				      size_t orc_ip_size, void *orc,

				      size_t orc_size) {}



#ifdef CONFIG_KASAN

/*

 * This disables KASAN checking when reading a value from another task's stack,

 * since the other task could be running on another CPU and could have poisoned

 * the stack in the meantime.

 */

#define READ_ONCE_TASK_STACK(task, x)			\

({							\

	unsigned long val;				\

	if (task == current)				\

		val = READ_ONCE(x);			\

	else						\

		val = READ_ONCE_NOCHECK(x);		\

	val;						\

})

#else

#define READ_ONCE_TASK_STACK(task, x) READ_ONCE(x)

#endif



#endif /* _ASM_S390_UNWIND_H */

arch/s390/kernel/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ CFLAGS_smp.o := -Wno-nonnull 
#

CFLAGS_stacktrace.o	+= -fno-optimize-sibling-calls

CFLAGS_dumpstack.o	+= -fno-optimize-sibling-calls

CFLAGS_unwind_bc.o	+= -fno-optimize-sibling-calls



#

# Pass UTS_MACHINE for user_regset definition
@@ -51,7 +52,7 @@ obj-y += debug.o irq.o ipl.o dis.o diag.o vdso.o early_nobss.o 
obj-y	+= sysinfo.o lgr.o os_info.o machine_kexec.o pgm_check.o

obj-y	+= runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o

obj-y	+= entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o

obj-y	+= nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o

obj-y	+= nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o unwind_bc.o



extra-y				+= head64.o vmlinux.lds

arch/s390/kernel/asm-offsets.c

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <asm/pgtable.h>

#include <asm/gmap.h>

#include <asm/nmi.h>

#include <asm/stacktrace.h>



int main(void)

{