Commit 2e83e0eb authored by Vasily Gorbik's avatar Vasily Gorbik

s390: clean .bss before running uncompressed kernel

Clean uncompressed kernel .bss section in the startup code before
the uncompressed kernel is executed. At this point of time initrd and
certificates have been already rescued. Uncompressed kernel .bss size
is known from vmlinux_info. It is also taken into consideration during
uncompressed kernel positioning by kaslr (so it is safe to clean it).

With that uncompressed kernel is starting with .bss section zeroed and
no .bss section usage restrictions apply. Which makes chkbss checks for
uncompressed kernel objects obsolete and they can be removed.

early_nobss.c is also not needed anymore. Parts of it which are still
relevant are moved to early.c. Kasan initialization code is now called
directly from head64 (early.c is instrumented and should not be
executed before kasan shadow memory is set up).
Reviewed-by: default avatarPhilipp Rudo <prudo@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 19413fe0
...@@ -112,6 +112,11 @@ static void handle_relocs(unsigned long offset) ...@@ -112,6 +112,11 @@ static void handle_relocs(unsigned long offset)
} }
} }
static void clear_bss_section(void)
{
memset((void *)vmlinux.default_lma + vmlinux.image_size, 0, vmlinux.bss_size);
}
void startup_kernel(void) void startup_kernel(void)
{ {
unsigned long random_lma; unsigned long random_lma;
...@@ -151,6 +156,7 @@ void startup_kernel(void) ...@@ -151,6 +156,7 @@ void startup_kernel(void)
} else if (__kaslr_offset) } else if (__kaslr_offset)
memcpy((void *)vmlinux.default_lma, img, vmlinux.image_size); memcpy((void *)vmlinux.default_lma, img, vmlinux.image_size);
clear_bss_section();
copy_bootdata(); copy_bootdata();
if (IS_ENABLED(CONFIG_RELOCATABLE)) if (IS_ENABLED(CONFIG_RELOCATABLE))
handle_relocs(__kaslr_offset); handle_relocs(__kaslr_offset);
......
...@@ -10,20 +10,12 @@ CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE) ...@@ -10,20 +10,12 @@ CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
# Do not trace early setup code # Do not trace early setup code
CFLAGS_REMOVE_early.o = $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_early.o = $(CC_FLAGS_FTRACE)
CFLAGS_REMOVE_early_nobss.o = $(CC_FLAGS_FTRACE)
endif endif
GCOV_PROFILE_early.o := n GCOV_PROFILE_early.o := n
GCOV_PROFILE_early_nobss.o := n
KCOV_INSTRUMENT_early.o := n KCOV_INSTRUMENT_early.o := n
KCOV_INSTRUMENT_early_nobss.o := n
UBSAN_SANITIZE_early.o := n UBSAN_SANITIZE_early.o := n
UBSAN_SANITIZE_early_nobss.o := n
KASAN_SANITIZE_early_nobss.o := n
KASAN_SANITIZE_ipl.o := n KASAN_SANITIZE_ipl.o := n
KASAN_SANITIZE_machine_kexec.o := n KASAN_SANITIZE_machine_kexec.o := n
...@@ -48,7 +40,7 @@ CFLAGS_ptrace.o += -DUTS_MACHINE='"$(UTS_MACHINE)"' ...@@ -48,7 +40,7 @@ CFLAGS_ptrace.o += -DUTS_MACHINE='"$(UTS_MACHINE)"'
obj-y := traps.o time.o process.o base.o early.o setup.o idle.o vtime.o obj-y := traps.o time.o process.o base.o early.o setup.o idle.o vtime.o
obj-y += processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o obj-y += processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o
obj-y += debug.o irq.o ipl.o dis.o diag.o vdso.o early_nobss.o obj-y += debug.o irq.o ipl.o dis.o diag.o vdso.o
obj-y += sysinfo.o lgr.o os_info.o machine_kexec.o pgm_check.o obj-y += sysinfo.o lgr.o os_info.o machine_kexec.o pgm_check.o
obj-y += runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o obj-y += runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
obj-y += entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o obj-y += entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
...@@ -90,6 +82,3 @@ obj-$(CONFIG_TRACEPOINTS) += trace.o ...@@ -90,6 +82,3 @@ obj-$(CONFIG_TRACEPOINTS) += trace.o
# vdso # vdso
obj-y += vdso64/ obj-y += vdso64/
obj-$(CONFIG_COMPAT_VDSO) += vdso32/ obj-$(CONFIG_COMPAT_VDSO) += vdso32/
chkbss := head64.o early_nobss.o
include $(srctree)/arch/s390/scripts/Makefile.chkbss
...@@ -32,6 +32,21 @@ ...@@ -32,6 +32,21 @@
#include <asm/boot_data.h> #include <asm/boot_data.h>
#include "entry.h" #include "entry.h"
static void __init reset_tod_clock(void)
{
u64 time;
if (store_tod_clock(&time) == 0)
return;
/* TOD clock not running. Set the clock to Unix Epoch. */
if (set_tod_clock(TOD_UNIX_EPOCH) != 0 || store_tod_clock(&time) != 0)
disabled_wait();
memset(tod_clock_base, 0, 16);
*(__u64 *) &tod_clock_base[1] = TOD_UNIX_EPOCH;
S390_lowcore.last_update_clock = TOD_UNIX_EPOCH;
}
/* /*
* Initialize storage key for kernel pages * Initialize storage key for kernel pages
*/ */
...@@ -301,6 +316,7 @@ static void __init check_image_bootable(void) ...@@ -301,6 +316,7 @@ static void __init check_image_bootable(void)
void __init startup_init(void) void __init startup_init(void)
{ {
reset_tod_clock();
check_image_bootable(); check_image_bootable();
time_early_init(); time_early_init();
init_kernel_storage_key(); init_kernel_storage_key();
......
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright IBM Corp. 2007, 2018
*/
/*
* Early setup functions which may not rely on an initialized bss
* section. The last thing that is supposed to happen here is
* initialization of the bss section.
*/
#include <linux/processor.h>
#include <linux/string.h>
#include <asm/sections.h>
#include <asm/lowcore.h>
#include <asm/timex.h>
#include <asm/kasan.h>
#include "entry.h"
static void __init reset_tod_clock(void)
{
u64 time;
if (store_tod_clock(&time) == 0)
return;
/* TOD clock not running. Set the clock to Unix Epoch. */
if (set_tod_clock(TOD_UNIX_EPOCH) != 0 || store_tod_clock(&time) != 0)
disabled_wait();
memset(tod_clock_base, 0, 16);
*(__u64 *) &tod_clock_base[1] = TOD_UNIX_EPOCH;
S390_lowcore.last_update_clock = TOD_UNIX_EPOCH;
}
static void __init clear_bss_section(void)
{
memset(__bss_start, 0, __bss_stop - __bss_start);
}
void __init startup_init_nobss(void)
{
reset_tod_clock();
clear_bss_section();
kasan_early_init();
}
...@@ -34,11 +34,9 @@ ENTRY(startup_continue) ...@@ -34,11 +34,9 @@ ENTRY(startup_continue)
larl %r14,init_task larl %r14,init_task
stg %r14,__LC_CURRENT stg %r14,__LC_CURRENT
larl %r15,init_thread_union+THREAD_SIZE-STACK_FRAME_OVERHEAD larl %r15,init_thread_union+THREAD_SIZE-STACK_FRAME_OVERHEAD
# #ifdef CONFIG_KASAN
# Early setup functions that may not rely on an initialized bss section, brasl %r14,kasan_early_init
# like moving the initrd. Returns with an initialized bss section. #endif
#
brasl %r14,startup_init_nobss
# #
# Early machine initialization and detection functions. # Early machine initialization and detection functions.
# #
......
...@@ -11,6 +11,3 @@ lib-$(CONFIG_UPROBES) += probes.o ...@@ -11,6 +11,3 @@ lib-$(CONFIG_UPROBES) += probes.o
# Instrumenting memory accesses to __user data (in different address space) # Instrumenting memory accesses to __user data (in different address space)
# produce false positives # produce false positives
KASAN_SANITIZE_uaccess.o := n KASAN_SANITIZE_uaccess.o := n
chkbss := mem.o
include $(srctree)/arch/s390/scripts/Makefile.chkbss
...@@ -49,6 +49,3 @@ obj-$(CONFIG_CRASH_DUMP) += sclp_sdias.o zcore.o ...@@ -49,6 +49,3 @@ obj-$(CONFIG_CRASH_DUMP) += sclp_sdias.o zcore.o
hmcdrv-objs := hmcdrv_mod.o hmcdrv_dev.o hmcdrv_ftp.o hmcdrv_cache.o diag_ftp.o sclp_ftp.o hmcdrv-objs := hmcdrv_mod.o hmcdrv_dev.o hmcdrv_ftp.o hmcdrv_cache.o diag_ftp.o sclp_ftp.o
obj-$(CONFIG_HMC_DRV) += hmcdrv.o obj-$(CONFIG_HMC_DRV) += hmcdrv.o
chkbss := sclp_early_core.o
include $(srctree)/arch/s390/scripts/Makefile.chkbss
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment