From 2e83e0eb85ca62985406920f97ece36d822d421f Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Sun, 11 Aug 2019 20:55:18 +0200 Subject: [PATCH] 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: Philipp Rudo Signed-off-by: Vasily Gorbik --- arch/s390/boot/startup.c | 6 +++++ arch/s390/kernel/Makefile | 13 +--------- arch/s390/kernel/early.c | 16 ++++++++++++ arch/s390/kernel/early_nobss.c | 45 ---------------------------------- arch/s390/kernel/head64.S | 8 +++--- arch/s390/lib/Makefile | 3 --- drivers/s390/char/Makefile | 3 --- 7 files changed, 26 insertions(+), 68 deletions(-) delete mode 100644 arch/s390/kernel/early_nobss.c diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index 7b0d05414618..596ca7cc4d7b 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -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) { unsigned long random_lma; @@ -151,6 +156,7 @@ void startup_kernel(void) } else if (__kaslr_offset) memcpy((void *)vmlinux.default_lma, img, vmlinux.image_size); + clear_bss_section(); copy_bootdata(); if (IS_ENABLED(CONFIG_RELOCATABLE)) handle_relocs(__kaslr_offset); diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile index 0f255b54b051..7edbbcd8228a 100644 --- a/arch/s390/kernel/Makefile +++ b/arch/s390/kernel/Makefile @@ -10,20 +10,12 @@ CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE) # Do not trace early setup code CFLAGS_REMOVE_early.o = $(CC_FLAGS_FTRACE) -CFLAGS_REMOVE_early_nobss.o = $(CC_FLAGS_FTRACE) endif GCOV_PROFILE_early.o := n -GCOV_PROFILE_early_nobss.o := n - KCOV_INSTRUMENT_early.o := n -KCOV_INSTRUMENT_early_nobss.o := n - UBSAN_SANITIZE_early.o := n -UBSAN_SANITIZE_early_nobss.o := n - -KASAN_SANITIZE_early_nobss.o := n KASAN_SANITIZE_ipl.o := n KASAN_SANITIZE_machine_kexec.o := n @@ -48,7 +40,7 @@ CFLAGS_ptrace.o += -DUTS_MACHINE='"$(UTS_MACHINE)"' obj-y := traps.o time.o process.o base.o early.o setup.o idle.o vtime.o obj-y += 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 += 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 @@ -90,6 +82,3 @@ obj-$(CONFIG_TRACEPOINTS) += trace.o # vdso obj-y += vdso64/ obj-$(CONFIG_COMPAT_VDSO) += vdso32/ - -chkbss := head64.o early_nobss.o -include $(srctree)/arch/s390/scripts/Makefile.chkbss diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c index 6312fed48530..b432d63d0b37 100644 --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -32,6 +32,21 @@ #include #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 */ @@ -301,6 +316,7 @@ static void __init check_image_bootable(void) void __init startup_init(void) { + reset_tod_clock(); check_image_bootable(); time_early_init(); init_kernel_storage_key(); diff --git a/arch/s390/kernel/early_nobss.c b/arch/s390/kernel/early_nobss.c deleted file mode 100644 index 52a3ef959341..000000000000 --- a/arch/s390/kernel/early_nobss.c +++ /dev/null @@ -1,45 +0,0 @@ -// 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 -#include -#include -#include -#include -#include -#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(); -} diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S index 5aea1a527443..143ed71221fe 100644 --- a/arch/s390/kernel/head64.S +++ b/arch/s390/kernel/head64.S @@ -34,11 +34,9 @@ ENTRY(startup_continue) larl %r14,init_task stg %r14,__LC_CURRENT larl %r15,init_thread_union+THREAD_SIZE-STACK_FRAME_OVERHEAD -# -# Early setup functions that may not rely on an initialized bss section, -# like moving the initrd. Returns with an initialized bss section. -# - brasl %r14,startup_init_nobss +#ifdef CONFIG_KASAN + brasl %r14,kasan_early_init +#endif # # Early machine initialization and detection functions. # diff --git a/arch/s390/lib/Makefile b/arch/s390/lib/Makefile index a1ec63abfb95..d7c218e8b559 100644 --- a/arch/s390/lib/Makefile +++ b/arch/s390/lib/Makefile @@ -11,6 +11,3 @@ lib-$(CONFIG_UPROBES) += probes.o # Instrumenting memory accesses to __user data (in different address space) # produce false positives KASAN_SANITIZE_uaccess.o := n - -chkbss := mem.o -include $(srctree)/arch/s390/scripts/Makefile.chkbss diff --git a/drivers/s390/char/Makefile b/drivers/s390/char/Makefile index b8a8816d94e7..845e12ac5954 100644 --- a/drivers/s390/char/Makefile +++ b/drivers/s390/char/Makefile @@ -49,6 +49,3 @@ obj-$(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 obj-$(CONFIG_HMC_DRV) += hmcdrv.o - -chkbss := sclp_early_core.o -include $(srctree)/arch/s390/scripts/Makefile.chkbss -- GitLab