s390/boot: make stacks part of the decompressor's image

Instead of using constant addresses for the normal and dump-info stacks,
allocate both stacks in the decompressor's image and load the stack register
in a position-independent manner.

This will allow loading and entering the decompressor at an arbitrary
memory address without corrupting the content at the fixed addresses
used until now for both stacks. This is one of the prerequisites
for being able to kexec the decompressor from its load address without
relocating it first.

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/boot/boot.h b/arch/s390/boot/boot.h
index 937dbdd0ef4350257ddce7b9156e6a61d5d24462..3d7d5ef4d16900374fd758afd719c37574bde73d 100644 (file)
--- a/arch/s390/boot/boot.h
+++ b/arch/s390/boot/boot.h
@@ -2,13 +2,8 @@
 #ifndef BOOT_BOOT_H
 #define BOOT_BOOT_H
 
-#include <linux/types.h>
-
-#define BOOT_STACK_OFFSET 0x8000
-
-#ifndef __ASSEMBLY__
-
 #include <asm/extable.h>
+#include <linux/types.h>
 
 void startup_kernel(void);
 unsigned long detect_memory(void);
@@ -35,8 +30,8 @@ extern char _stext_dma[], _etext_dma[];
 extern struct exception_table_entry _start_dma_ex_table[];
 extern struct exception_table_entry _stop_dma_ex_table[];
 extern char _decompressor_syms_start[], _decompressor_syms_end[];
+extern char _stack_start[], _stack_end[];
 
 unsigned long read_ipl_report(unsigned long safe_offset);
 
-#endif /* __ASSEMBLY__ */
 #endif /* BOOT_BOOT_H */

diff --git a/arch/s390/boot/compressed/vmlinux.lds.S b/arch/s390/boot/compressed/vmlinux.lds.S
index 27a09c1c78f6a701fac12b0f9d9150a389675ad6..0bd8aaaa4b3326215b46a34b8ace66fd33667622 100644 (file)
--- a/arch/s390/boot/compressed/vmlinux.lds.S
+++ b/arch/s390/boot/compressed/vmlinux.lds.S
@@ -1,6 +1,8 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <asm-generic/vmlinux.lds.h>
 #include <asm/vmlinux.lds.h>
+#include <asm/thread_info.h>
+#include <asm/page.h>
 
 OUTPUT_FORMAT("elf64-s390", "elf64-s390", "elf64-s390")
 OUTPUT_ARCH(s390:64-bit)
@@ -69,6 +71,17 @@ SECTIONS
                *(.bss)
                *(.bss.*)
                *(COMMON)
+               /*
+                * Stacks for the decompressor
+                */
+               . = ALIGN(PAGE_SIZE);
+               _dump_info_stack_start = .;
+               . += PAGE_SIZE;
+               _dump_info_stack_end = .;
+               . = ALIGN(PAGE_SIZE);
+               _stack_start = .;
+               . += BOOT_STACK_SIZE;
+               _stack_end = .;
                _ebss = .;
        }
 

diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
index 51693cfb65c2c3b35c9fcd87d6e19e6404876462..cafe454703b82648b39574f18cf8565cded19e9d 100644 (file)
--- a/arch/s390/boot/head.S
+++ b/arch/s390/boot/head.S
@@ -25,10 +25,8 @@
 #include <linux/init.h>
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
-#include <asm/thread_info.h>
 #include <asm/page.h>
 #include <asm/ptrace.h>
-#include "boot.h"
 
 #define ARCH_OFFSET    4
 
@@ -320,13 +318,11 @@ SYM_CODE_START_LOCAL(startup_normal)
        mvc     __LC_LAST_UPDATE_CLOCK(8),__LC_BOOT_CLOCK+1
        spt     6f-.LPG0(%r13)
        mvc     __LC_LAST_UPDATE_TIMER(8),6f-.LPG0(%r13)
-       l       %r15,.Lstack-.LPG0(%r13)
+       larl    %r15,_stack_end-STACK_FRAME_OVERHEAD
        brasl   %r14,verify_facilities
        brasl   %r14,startup_kernel
 SYM_CODE_END(startup_normal)
 
-.Lstack:
-       .long   BOOT_STACK_OFFSET + BOOT_STACK_SIZE - STACK_FRAME_OVERHEAD
        .align  8
 6:     .long   0x7fffffff,0xffffffff
 .Lext_new_psw:
@@ -386,15 +382,13 @@ SYM_CODE_START_LOCAL(startup_pgm_check_handler)
        oi      __LC_RETURN_PSW+1,0x2   # set wait state bit
        larl    %r9,.Lold_psw_disabled_wait
        stg     %r9,__LC_PGM_NEW_PSW+8
-       l       %r15,.Ldump_info_stack-.Lold_psw_disabled_wait(%r9)
+       larl    %r15,_dump_info_stack_end-STACK_FRAME_OVERHEAD
        brasl   %r14,print_pgm_check_info
 .Lold_psw_disabled_wait:
        la      %r8,4095
        lmg     %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r8)
        lpswe   __LC_RETURN_PSW         # disabled wait
 SYM_CODE_END(startup_pgm_check_handler)
-.Ldump_info_stack:
-       .long   0x5000 + PAGE_SIZE - STACK_FRAME_OVERHEAD
 
 #
 # params at 10400 (setup.h)

diff --git a/arch/s390/boot/pgm_check_info.c b/arch/s390/boot/pgm_check_info.c
index 7126a1b3293deb9c3295a586cf6508bb4c2c9cf1..209f6ae5a1972b5f7cf74dca8ab63c22b7b38995 100644 (file)
--- a/arch/s390/boot/pgm_check_info.c
+++ b/arch/s390/boot/pgm_check_info.c
@@ -125,8 +125,8 @@ out:
 
 static noinline void print_stacktrace(void)
 {
-       struct stack_info boot_stack = { STACK_TYPE_TASK, BOOT_STACK_OFFSET,
-                                        BOOT_STACK_OFFSET + BOOT_STACK_SIZE };
+       struct stack_info boot_stack = { STACK_TYPE_TASK, (unsigned long)_stack_start,
+                                        (unsigned long)_stack_end };
        unsigned long sp = S390_lowcore.gpregs_save_area[15];
        bool first = true;