Commit 74ca317c authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
Browse files

kexec: create a new config option CONFIG_KEXEC_FILE for new syscall 



Currently new system call kexec_file_load() and all the associated code
compiles if CONFIG_KEXEC=y.  But new syscall also compiles purgatory
code which currently uses gcc option -mcmodel=large.  This option seems
to be available only gcc 4.4 onwards.

Hiding new functionality behind a new config option will not break
existing users of old gcc.  Those who wish to enable new functionality
will require new gcc.  Having said that, I am trying to figure out how
can I move away from using -mcmodel=large but that can take a while.

I think there are other advantages of introducing this new config
option.  As this option will be enabled only on x86_64, other arches
don't have to compile generic kexec code which will never be used.  This
new code selects CRYPTO=y and CRYPTO_SHA256=y.  And all other arches had
to do this for CONFIG_KEXEC.  Now with introduction of new config
option, we can remove crypto dependency from other arches.

Now CONFIG_KEXEC_FILE is available only on x86_64.  So whereever I had
CONFIG_X86_64 defined, I got rid of that.

For CONFIG_KEXEC_FILE, instead of doing select CRYPTO=y, I changed it to
"depends on CRYPTO=y".  This should be safer as "select" is not
recursive.

Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Tested-by: default avatarShaun Ruffell <sruffell@digium.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b38af472

arch/x86/Kbuild

+1 −3
Original line number Diff line number Diff line
@@ -17,6 +17,4 @@ obj-$(CONFIG_IA32_EMULATION) += ia32/ 
obj-y += platform/

obj-y += net/



ifeq ($(CONFIG_X86_64),y)

obj-$(CONFIG_KEXEC) += purgatory/

endif
 
obj-$(CONFIG_KEXEC_FILE) += purgatory/

arch/x86/Kconfig

+14 −4
Original line number Diff line number Diff line
@@ -1585,9 +1585,6 @@ source kernel/Kconfig.hz 


config KEXEC

	bool "kexec system call"

	select BUILD_BIN2C

	select CRYPTO

	select CRYPTO_SHA256

	---help---

	  kexec is a system call that implements the ability to shutdown your

	  current kernel, and to start another kernel.  It is like a reboot
@@ -1602,9 +1599,22 @@ config KEXEC 
	  interface is strongly in flux, so no good recommendation can be

	  made.



config KEXEC_FILE

	bool "kexec file based system call"

	select BUILD_BIN2C

	depends on KEXEC

	depends on X86_64

	depends on CRYPTO=y

	depends on CRYPTO_SHA256=y

	---help---

	  This is new version of kexec system call. This system call is

	  file based and takes file descriptors as system call argument

	  for kernel and initramfs as opposed to list of segments as

	  accepted by previous system call.



config KEXEC_VERIFY_SIG

	bool "Verify kernel signature during kexec_file_load() syscall"

	depends on KEXEC

	depends on KEXEC_FILE

	---help---

	  This option makes kernel signature verification mandatory for

	  kexec_file_load() syscall. If kernel is signature can not be

arch/x86/Makefile

+1 −4
Original line number Diff line number Diff line
@@ -184,12 +184,9 @@ archheaders: 
	$(Q)$(MAKE) $(build)=arch/x86/syscalls all



archprepare:

ifeq ($(CONFIG_KEXEC),y)

# Build only for 64bit. No loaders for 32bit yet.

 ifeq ($(CONFIG_X86_64),y)

ifeq ($(CONFIG_KEXEC_FILE),y)

	$(Q)$(MAKE) $(build)=arch/x86/purgatory arch/x86/purgatory/kexec-purgatory.c

endif

endif



###

# Kernel objects

arch/x86/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o 
obj-$(CONFIG_X86_TSC)		+= trace_clock.o

obj-$(CONFIG_KEXEC)		+= machine_kexec_$(BITS).o

obj-$(CONFIG_KEXEC)		+= relocate_kernel_$(BITS).o crash.o

obj-$(CONFIG_KEXEC_FILE)	+= kexec-bzimage64.o

obj-$(CONFIG_CRASH_DUMP)	+= crash_dump_$(BITS).o

obj-y				+= kprobes/

obj-$(CONFIG_MODULES)		+= module.o
@@ -118,5 +119,4 @@ ifeq ($(CONFIG_X86_64),y) 


	obj-$(CONFIG_PCI_MMCONFIG)	+= mmconf-fam10h_64.o

	obj-y				+= vsmp_64.o

	obj-$(CONFIG_KEXEC)		+= kexec-bzimage64.o

endif

arch/x86/kernel/crash.c

+2 −4
Original line number Diff line number Diff line
@@ -182,8 +182,7 @@ void native_machine_crash_shutdown(struct pt_regs *regs) 
	crash_save_cpu(regs, safe_smp_processor_id());

}



#ifdef CONFIG_X86_64



#ifdef CONFIG_KEXEC_FILE

static int get_nr_ram_ranges_callback(unsigned long start_pfn,

				unsigned long nr_pfn, void *arg)

{
@@ -696,5 +695,4 @@ int crash_load_segments(struct kimage *image) 


	return ret;

}



#endif /* CONFIG_X86_64 */
 
#endif /* CONFIG_KEXEC_FILE */

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