Commit 8977ab65 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Heiko Carstens
Browse files

s390/decompressor: add stacktrace support 



Decompressor works on a single statically allocated stack. Stacktrace
implementation with -mbackchain just takes few lines of code.

Linux version 5.10.0-rc3-22793-g0f84a355b776-dirty (gor@tuxmaker) #27 SMP PREEMPT Mon Nov 9 17:30:18 CET 2020
Kernel fault: interruption code 0005 ilc:2
PSW : 0000000180000000 0000000000012f92 (parse_boot_command_line+0x27a/0x46c)
      R:0 T:0 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:0 CC:0 PM:0 RI:0 EA:3
GPRS: 0000000000000000 00ffffffffffffff 0000000000000000 000000000001a62c
      000000000000bf60 0000000000000000 00000000000003c0 0000000000000000
      0000000000000080 000000000002322d 000000007f29ef20 0000000000efd018
      000000000311c000 0000000000010070 0000000000012f82 000000000000bea8
Call Trace:
(sp:000000000000bea8 [<000000000002016e>] 000000000002016e)
 sp:000000000000bf18 [<0000000000012408>] startup_kernel+0x88/0x2fc
 sp:000000000000bf60 [<00000000000100c4>] startup_normal+0xb0/0xb0

Reviewed-by: default avatarAlexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 24621896

arch/s390/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ KBUILD_AFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -D__ASSEMBLY__ 
KBUILD_AFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),$(aflags_dwarf))

KBUILD_CFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -O2

KBUILD_CFLAGS_DECOMPRESSOR += -DDISABLE_BRANCH_PROFILING -D__NO_FORTIFY

KBUILD_CFLAGS_DECOMPRESSOR += -fno-delete-null-pointer-checks -msoft-float

KBUILD_CFLAGS_DECOMPRESSOR += -fno-delete-null-pointer-checks -msoft-float -mbackchain

KBUILD_CFLAGS_DECOMPRESSOR += -fno-asynchronous-unwind-tables

KBUILD_CFLAGS_DECOMPRESSOR += -ffreestanding

KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, address-of-packed-member)

arch/s390/boot/boot.h

+5 −0
Original line number Diff line number Diff line
@@ -4,6 +4,10 @@ 


#include <linux/types.h>



#define BOOT_STACK_OFFSET 0x8000



#ifndef __ASSEMBLY__



#include <linux/compiler.h>



void startup_kernel(void);
@@ -25,4 +29,5 @@ extern int kaslr_enabled; 


unsigned long read_ipl_report(unsigned long safe_offset);



#endif /* __ASSEMBLY__ */

#endif /* BOOT_BOOT_H */

arch/s390/boot/head.S

+2 −1
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <asm/thread_info.h>

#include <asm/page.h>

#include <asm/ptrace.h>

#include "boot.h"



#define ARCH_OFFSET	4
@@ -325,7 +326,7 @@ SYM_CODE_START_LOCAL(startup_normal) 
SYM_CODE_END(startup_normal)



.Lstack:

	.long	0x8000 + (1<<(PAGE_SHIFT+BOOT_STACK_ORDER)) - STACK_FRAME_OVERHEAD

	.long	BOOT_STACK_OFFSET + BOOT_STACK_SIZE - STACK_FRAME_OVERHEAD

	.align	8

6:	.long	0x7fffffff,0xffffffff

.Lext_new_psw:

arch/s390/boot/pgm_check_info.c

+23 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#include <linux/kernel.h>

#include <linux/string.h>

#include <linux/ctype.h>

#include <asm/stacktrace.h>

#include <asm/lowcore.h>

#include <asm/setup.h>

#include <asm/sclp.h>
@@ -121,6 +122,27 @@ void decompressor_printk(const char *fmt, ...) 
	sclp_early_printk(buf);

}



static noinline void print_stacktrace(void)

{

	struct stack_info boot_stack = { STACK_TYPE_TASK, BOOT_STACK_OFFSET,

					 BOOT_STACK_OFFSET + BOOT_STACK_SIZE };

	unsigned long sp = S390_lowcore.gpregs_save_area[15];

	bool first = true;



	decompressor_printk("Call Trace:\n");

	while (!(sp & 0x7) && on_stack(&boot_stack, sp, sizeof(struct stack_frame))) {

		struct stack_frame *sf = (struct stack_frame *)sp;



		decompressor_printk(first ? "(sp:%016lx [<%016lx>] %pS)\n" :

					    " sp:%016lx [<%016lx>] %pS\n",

				    sp, sf->gprs[8], (void *)sf->gprs[8]);

		if (sf->back_chain <= sp)

			break;

		sp = sf->back_chain;

		first = false;

	}

}



void print_pgm_check_info(void)

{

	unsigned long *gpregs = (unsigned long *)S390_lowcore.gpregs_save_area;
@@ -148,4 +170,5 @@ void print_pgm_check_info(void) 
			    gpregs[8], gpregs[9], gpregs[10], gpregs[11]);

	decompressor_printk("      %016lx %016lx %016lx %016lx\n",

			    gpregs[12], gpregs[13], gpregs[14], gpregs[15]);

	print_stacktrace();

}

arch/s390/include/asm/thread_info.h

+1 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ 
#else

#define THREAD_SIZE_ORDER 2

#endif

#define BOOT_STACK_ORDER  2

#define BOOT_STACK_SIZE (PAGE_SIZE << 2)

#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)



#ifndef __ASSEMBLY__