kexec: refactor CONFIG_KEXEC/CONFIG_KEXEC_FILE Kconfig

Because there's general code need CONFIG_KEXEC_CORE, so I updated all the architecture Kconfig with a new option KEXEC_CORE, and let KEXEC selects KEXEC_CORE in arch Kconfig. Also updated general kernel code with to kexec_load syscall.

Signed-off-by Dave Young <[email protected]>

---
 arch/arm/Kconfig              |    4 +
 arch/ia64/Kconfig             |    4 +
 arch/m68k/Kconfig             |    4 +
 arch/mips/Kconfig             |    4 +
 arch/powerpc/Kconfig          |    4 +
 arch/sh/Kconfig               |    4 +
 arch/tile/Kconfig             |    4 +
 arch/x86/Kconfig              |    6 +-
 arch/x86/boot/header.S        |    2 +-
 arch/x86/include/asm/kdebug.h |    2 +-
 arch/x86/kernel/Makefile      |    4 +-
 arch/x86/kernel/kvmclock.c    |    4 +-
 arch/x86/kernel/reboot.c      |    4 +-
 arch/x86/kernel/setup.c       |    2 +-
 arch/x86/kernel/vmlinux.lds.S |    2 +-
 arch/x86/kvm/vmx.c            |    8 +-
 arch/x86/platform/efi/efi.c   |    4 +-
 arch/x86/platform/uv/uv_nmi.c |    6 +-
 drivers/firmware/efi/Kconfig  |    2 +-
 drivers/pci/pci-driver.c      |    2 +-
 include/linux/kexec.h         |   12 +-
 init/initramfs.c              |    4 +-
 kernel/Makefile               |    1 +
 kernel/events/core.c          |    2 +-
 kernel/kexec.c                | 1578 +---------------------------------------
 kernel/kexec_core.c           | 1594 +++++++++++++++++++++++++++++++++++++++++
 kernel/ksysfs.c               |    6 +-
 kernel/printk/printk.c        |    2 +-
 kernel/reboot.c               |    2 +-
 kernel/sysctl.c               |    2 +-
 30 files changed, 1668 insertions(+), 1611 deletions(-)
 create mode 100644 kernel/kexec_core.c

arch/arm/Kconfig +1 -0

index 1c50210..20c48b3 100644
@@ -2001,10 +2001,14 @@ config XIP_PHYS_ADDR
          be linked for and stored to.  This address is dependent on your
          own flash usage.
 
+config KEXEC_CORE

Quoted 49 lines · On Mon, Jul 13, 2015 at 4:13 AM, <[email protected]> wrote:

Because there's general code need CONFIG_KEXEC_CORE, so I updated all the architecture Kconfig with a new option KEXEC_CORE, and let KEXEC selects KEXEC_CORE in arch Kconfig. Also updated general kernel code with to kexec_load syscall.

Signed-off-by Dave Young <[email protected]>

---
 arch/arm/Kconfig              |    4 +
 arch/ia64/Kconfig             |    4 +
 arch/m68k/Kconfig             |    4 +
 arch/mips/Kconfig             |    4 +
 arch/powerpc/Kconfig          |    4 +
 arch/sh/Kconfig               |    4 +
 arch/tile/Kconfig             |    4 +
 arch/x86/Kconfig              |    6 +-
 arch/x86/boot/header.S        |    2 +-
 arch/x86/include/asm/kdebug.h |    2 +-
 arch/x86/kernel/Makefile      |    4 +-
 arch/x86/kernel/kvmclock.c    |    4 +-
 arch/x86/kernel/reboot.c      |    4 +-
 arch/x86/kernel/setup.c       |    2 +-
 arch/x86/kernel/vmlinux.lds.S |    2 +-
 arch/x86/kvm/vmx.c            |    8 +-
 arch/x86/platform/efi/efi.c   |    4 +-
 arch/x86/platform/uv/uv_nmi.c |    6 +-
 drivers/firmware/efi/Kconfig  |    2 +-
 drivers/pci/pci-driver.c      |    2 +-
 include/linux/kexec.h         |   12 +-
 init/initramfs.c              |    4 +-
 kernel/Makefile               |    1 +
 kernel/events/core.c          |    2 +-
 kernel/kexec.c                | 1578 +---------------------------------------
 kernel/kexec_core.c           | 1594 +++++++++++++++++++++++++++++++++++++++++
 kernel/ksysfs.c               |    6 +-
 kernel/printk/printk.c        |    2 +-
 kernel/reboot.c               |    2 +-
 kernel/sysctl.c               |    2 +-
 30 files changed, 1668 insertions(+), 1611 deletions(-)
 create mode 100644 kernel/kexec_core.c

arch/arm/Kconfig +1 -0

index 1c50210..20c48b3 100644
@@ -2001,10 +2001,14 @@ config XIP_PHYS_ADDR
          be linked for and stored to.  This address is dependent on your
          own flash usage.
 
+config KEXEC_CORE

arch/arm/Kconfig config XIP_PHYS_ADDR · line 2014

Quoted 10 lines

arch/arm/Kconfig +3 -0

+       bool
+
 config KEXEC
        bool "Kexec system call (EXPERIMENTAL)"
        depends on (!SMP || PM_SLEEP_SMP)
        depends on !CPU_V7M
+       select KEXEC_CORE
        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

As this KEXEC_CORE is appearing in all arch/*/Kconfig files, I think it's time to add an ARCH_HAS_KEXEC symbol (to a common Kconfig file), and let arch/*/Kconfig select that if the architecture has kexec support.

Then KEXEC and KEXEC_CORE can live in the common Kconfig file, without the need to duplicate it.

Quoted 24 lines

Quoted 9 lines

arch/arm/Kconfig +1 -0

index 1c50210..20c48b3 100644
@@ -2001,10 +2001,14 @@ config XIP_PHYS_ADDR
          be linked for and stored to.  This address is dependent on your
          own flash usage.
 
+config KEXEC_CORE

arch/arm/Kconfig config XIP_PHYS_ADDR · line 2014

Quoted 10 lines

arch/arm/Kconfig +3 -0

+       bool
+
 config KEXEC
        bool "Kexec system call (EXPERIMENTAL)"
        depends on (!SMP || PM_SLEEP_SMP)
        depends on !CPU_V7M
+       select KEXEC_CORE
        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

As this KEXEC_CORE is appearing in all arch/*/Kconfig files, I think it's time to add an ARCH_HAS_KEXEC symbol (to a common Kconfig file), and let arch/*/Kconfig select that if the architecture has kexec support.

Quoted 2 lines

Then KEXEC and KEXEC_CORE can live in the common Kconfig file, without the need to duplicate it.

I'm not sure I understand your idea well, do you means like in arch/Kconfig add ARCH_HAS_KEXEC which depends on KEXEC_CORE?

How about simply move below chunk to arch/Kconfig instead of introducing another ARCH_HAS_KEXEC:
config KEXEC_CORE
bool

Hi Dave,

Quoted 27 lines · Dave Young

Quoted 26 lines

Quoted 9 lines

arch/arm/Kconfig +1 -0

index 1c50210..20c48b3 100644
@@ -2001,10 +2001,14 @@ config XIP_PHYS_ADDR
          be linked for and stored to.  This address is dependent on your
          own flash usage.
 
+config KEXEC_CORE

arch/arm/Kconfig config XIP_PHYS_ADDR · line 2014

Quoted 10 lines

arch/arm/Kconfig +3 -0

+       bool
+
 config KEXEC
        bool "Kexec system call (EXPERIMENTAL)"
        depends on (!SMP || PM_SLEEP_SMP)
        depends on !CPU_V7M
+       select KEXEC_CORE
        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

As this KEXEC_CORE is appearing in all arch/*/Kconfig files, I think it's time to add an ARCH_HAS_KEXEC symbol (to a common Kconfig file), and let arch/*/Kconfig select that if the architecture has kexec support.

Then KEXEC and KEXEC_CORE can live in the common Kconfig file, without the need to duplicate it.

Quoted 2 lines

I'm not sure I understand your idea well, do you means like in arch/Kconfig add ARCH_HAS_KEXEC which depends on KEXEC_CORE?

No, ARCH_HAS_KEXEC and all other KEXEC config options in arch/Kconfig. All other KEXEC config options should depend on ARCH_HAS_KEXEC, which can be selected by architectures that support kexec.

Quoted 5 lines

How about simply move below chunk to arch/Kconfig instead of introducing another ARCH_HAS_KEXEC:
config KEXEC_CORE
bool

Not all architectures support kexec, hence my proposed dependency on ARCH_HAS_KEXEC.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

Quoted 28 lines · Geert Uytterhoeven

Quoted 27 lines · Dave Young

Quoted 26 lines

Quoted 9 lines

arch/arm/Kconfig +1 -0

index 1c50210..20c48b3 100644
@@ -2001,10 +2001,14 @@ config XIP_PHYS_ADDR
          be linked for and stored to.  This address is dependent on your
          own flash usage.
 
+config KEXEC_CORE

arch/arm/Kconfig config XIP_PHYS_ADDR · line 2014

Quoted 10 lines

arch/arm/Kconfig +3 -0

+       bool
+
 config KEXEC
        bool "Kexec system call (EXPERIMENTAL)"
        depends on (!SMP || PM_SLEEP_SMP)
        depends on !CPU_V7M
+       select KEXEC_CORE
        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

As this KEXEC_CORE is appearing in all arch/*/Kconfig files, I think it's time to add an ARCH_HAS_KEXEC symbol (to a common Kconfig file), and let arch/*/Kconfig select that if the architecture has kexec support.

Then KEXEC and KEXEC_CORE can live in the common Kconfig file, without the need to duplicate it.

Quoted 6 lines

Quoted 2 lines

I'm not sure I understand your idea well, do you means like in arch/Kconfig add ARCH_HAS_KEXEC which depends on KEXEC_CORE?

No, ARCH_HAS_KEXEC and all other KEXEC config options in arch/Kconfig. All other KEXEC config options should depend on ARCH_HAS_KEXEC, which can be selected by architectures that support kexec.

So it will be like below? problem is KEXEC_FILE is x86 only now, how to handle it then?

arch/Kconfig:
config ARCH_HAS_KEXEC

        ...
config KEXEC_CORE
        ...

config KEXEC

        ...

config KEXEC_FILE

        ...

arch/arm/Kconfig:
select ARCH_HAS_KEXEC

Quoted 7 lines

Quoted 4 lines

How about simply move below chunk to arch/Kconfig instead of introducing another ARCH_HAS_KEXEC:
config KEXEC_CORE
bool

Not all architectures support kexec, hence my proposed dependency on ARCH_HAS_KEXEC.

KEXEC_CORE is not visible in menuconfig, it is selected by KEXEC and KEXEC_FILE so move it in arch/Kconfig is ok?

Hi Dave,

Quoted 39 lines · Dave Young

Quoted 28 lines · Geert Uytterhoeven

Quoted 27 lines · Dave Young

Quoted 26 lines

Quoted 9 lines

arch/arm/Kconfig +1 -0

index 1c50210..20c48b3 100644
@@ -2001,10 +2001,14 @@ config XIP_PHYS_ADDR
          be linked for and stored to.  This address is dependent on your
          own flash usage.
 
+config KEXEC_CORE

arch/arm/Kconfig config XIP_PHYS_ADDR · line 2014

Quoted 10 lines

arch/arm/Kconfig +3 -0

+       bool
+
 config KEXEC
        bool "Kexec system call (EXPERIMENTAL)"
        depends on (!SMP || PM_SLEEP_SMP)
        depends on !CPU_V7M
+       select KEXEC_CORE
        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

As this KEXEC_CORE is appearing in all arch/*/Kconfig files, I think it's time to add an ARCH_HAS_KEXEC symbol (to a common Kconfig file), and let arch/*/Kconfig select that if the architecture has kexec support.

Then KEXEC and KEXEC_CORE can live in the common Kconfig file, without the need to duplicate it.

Quoted 6 lines

Quoted 2 lines

I'm not sure I understand your idea well, do you means like in arch/Kconfig add ARCH_HAS_KEXEC which depends on KEXEC_CORE?

No, ARCH_HAS_KEXEC and all other KEXEC config options in arch/Kconfig. All other KEXEC config options should depend on ARCH_HAS_KEXEC, which can be selected by architectures that support kexec.

So it will be like below? problem is KEXEC_FILE is x86 only now, how to handle it then?

Quoted 6 lines

arch/Kconfig:
config ARCH_HAS_KEXEC

        ...
config KEXEC_CORE
        ...

config KEXEC

depends on ARCH_HAS_KEXEC

Quoted 2 lines

        ...

config KEXEC_FILE

depends on ARCH_HAS_KEXEC

Quoted 5 lines

        ...

arch/arm/Kconfig:
select ARCH_HAS_KEXEC

Right, that's the idea.

(Minor nit: ARM has dependencies for kexec, so it should be
"select ARCH_HAS_KEXEC if (!SMP || PM_SLEEP_SMP) && !CPU_V7M")

Quoted 5 lines

Quoted 5 lines

Quoted 4 lines

How about simply move below chunk to arch/Kconfig instead of introducing another ARCH_HAS_KEXEC:
config KEXEC_CORE
bool

Quoted 5 lines

Quoted 2 lines

Not all architectures support kexec, hence my proposed dependency on ARCH_HAS_KEXEC.

KEXEC_CORE is not visible in menuconfig, it is selected by KEXEC and KEXEC_FILE so move it in arch/Kconfig is ok?

Yes.

Quoted 49 lines · Geert Uytterhoeven

Quoted 39 lines · Dave Young

Quoted 28 lines · Geert Uytterhoeven

Quoted 27 lines · Dave Young

Quoted 26 lines

Quoted 9 lines

arch/arm/Kconfig +1 -0

index 1c50210..20c48b3 100644
@@ -2001,10 +2001,14 @@ config XIP_PHYS_ADDR
          be linked for and stored to.  This address is dependent on your
          own flash usage.
 
+config KEXEC_CORE

arch/arm/Kconfig config XIP_PHYS_ADDR · line 2014

Quoted 10 lines

arch/arm/Kconfig +3 -0

+       bool
+
 config KEXEC
        bool "Kexec system call (EXPERIMENTAL)"
        depends on (!SMP || PM_SLEEP_SMP)
        depends on !CPU_V7M
+       select KEXEC_CORE
        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

As this KEXEC_CORE is appearing in all arch/*/Kconfig files, I think it's time to add an ARCH_HAS_KEXEC symbol (to a common Kconfig file), and let arch/*/Kconfig select that if the architecture has kexec support.

Then KEXEC and KEXEC_CORE can live in the common Kconfig file, without the need to duplicate it.

Quoted 6 lines

Quoted 2 lines

I'm not sure I understand your idea well, do you means like in arch/Kconfig add ARCH_HAS_KEXEC which depends on KEXEC_CORE?

No, ARCH_HAS_KEXEC and all other KEXEC config options in arch/Kconfig. All other KEXEC config options should depend on ARCH_HAS_KEXEC, which can be selected by architectures that support kexec.

So it will be like below? problem is KEXEC_FILE is x86 only now, how to handle it then?

Quoted 6 lines

arch/Kconfig:
config ARCH_HAS_KEXEC

        ...
config KEXEC_CORE
        ...

config KEXEC

depends on ARCH_HAS_KEXEC

Quoted 4 lines

Quoted 2 lines

        ...

config KEXEC_FILE

depends on ARCH_HAS_KEXEC

But only x86 has KEXEC_FILE, if we make this change one will see KEXEC_FILE on arches other than x86..

Hi Dave,

Quoted 53 lines · Dave Young

Quoted 52 lines · Geert Uytterhoeven

Quoted 39 lines · Dave Young

Quoted 28 lines · Geert Uytterhoeven

Quoted 27 lines · Dave Young

Quoted 26 lines

Quoted 9 lines

arch/arm/Kconfig +1 -0

index 1c50210..20c48b3 100644
@@ -2001,10 +2001,14 @@ config XIP_PHYS_ADDR
          be linked for and stored to.  This address is dependent on your
          own flash usage.
 
+config KEXEC_CORE

arch/arm/Kconfig config XIP_PHYS_ADDR · line 2014

Quoted 10 lines

arch/arm/Kconfig +3 -0

+       bool
+
 config KEXEC
        bool "Kexec system call (EXPERIMENTAL)"
        depends on (!SMP || PM_SLEEP_SMP)
        depends on !CPU_V7M
+       select KEXEC_CORE
        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

As this KEXEC_CORE is appearing in all arch/*/Kconfig files, I think it's time to add an ARCH_HAS_KEXEC symbol (to a common Kconfig file), and let arch/*/Kconfig select that if the architecture has kexec support.

Then KEXEC and KEXEC_CORE can live in the common Kconfig file, without the need to duplicate it.

Quoted 6 lines

Quoted 2 lines

I'm not sure I understand your idea well, do you means like in arch/Kconfig add ARCH_HAS_KEXEC which depends on KEXEC_CORE?

No, ARCH_HAS_KEXEC and all other KEXEC config options in arch/Kconfig. All other KEXEC config options should depend on ARCH_HAS_KEXEC, which can be selected by architectures that support kexec.

So it will be like below? problem is KEXEC_FILE is x86 only now, how to handle it then?

Quoted 6 lines

arch/Kconfig:
config ARCH_HAS_KEXEC

        ...
config KEXEC_CORE
        ...

config KEXEC

depends on ARCH_HAS_KEXEC

Quoted 2 lines

        ...

config KEXEC_FILE

Quoted 4 lines

Quoted 1 line

depends on ARCH_HAS_KEXEC

But only x86 has KEXEC_FILE, if we make this change one will see KEXEC_FILE on arches other than x86..

Is there any technical reason why it's limited to x86?

Else we may need ARCH_HAS_KEXEC_FILE, too :-(

Previously Theodore Ts'o brought up an issue about kexec_load syscall bypassing signature verification:
https://lkml.org/lkml/2015/6/14/280

Because we have two kexec load syscall, one kexec_load, another kexec_file_load, the latter one was introduced by Vivek Goyal, it is mainly for supporting UEFI secure boot. kexec_file_load verifies kernel signature, but even if with CONFIG_KEXEC_VERIFY_SIG=y and CONFIG_KEXEC_FILE=y, kexec-tools still can use old syscall and bypass signature verification.

KEXEC_FILE can also be used without UEFI, so kexec can always verify kernel signature for security purpose.

The suggestion in above thread is add a new Kconfig option for kexec common code, here I use KEXEC_CORE, KEXEC and KEXEC_FILE select KEXEC_CORE so one can compile only KEXEC_FILE without old kexec_load syscall.

There's checkpatch warnings and errors, I would like to send furthuer cleanup patches after this series. Please let me know if you have other suggestions. checkpatch errors are for cases such as assign a value to static variables.

PATCH 3/3 can be sort out from the series if people do not like. It is a cleanup for a macro.

Quoted 21 lines · Dave Young

Previously Theodore Ts'o brought up an issue about kexec_load syscall bypassing signature verification:
https://lkml.org/lkml/2015/6/14/280

Because we have two kexec load syscall, one kexec_load, another kexec_file_load, the latter one was introduced by Vivek Goyal, it is mainly for supporting UEFI secure boot. kexec_file_load verifies kernel signature, but even if with CONFIG_KEXEC_VERIFY_SIG=y and CONFIG_KEXEC_FILE=y, kexec-tools still can use old syscall and bypass signature verification.

KEXEC_FILE can also be used without UEFI, so kexec can always verify kernel signature for security purpose.

The suggestion in above thread is add a new Kconfig option for kexec common code, here I use KEXEC_CORE, KEXEC and KEXEC_FILE select KEXEC_CORE so one can compile only KEXEC_FILE without old kexec_load syscall.

There's checkpatch warnings and errors, I would like to send furthuer cleanup patches after this series. Please let me know if you have other suggestions. checkpatch errors are for cases such as assign a value to static variables.

Quoted 2 lines

PATCH 3/3 can be sort out from the series if people do not like. It is a cleanup for a macro.

Since it is not related to the Kconfig cleanup thus I will drop it in next update, will send out as a standalone patch later.

Also there's a kexec-tools patch needed for testing KEXEC_FILE only, I forgot to mention, will take it in cover letter when I repost:

---
 kexec/crashdump-elf.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

kexec/crashdump-elf.c +5 -4

@@ -145,11 +145,12 @@ int FUNC(struct kexec_info *info,
 
 	count_cpu = nr_cpus;
 	for (i = 0; count_cpu > 0; i++) {
-		if (get_note_info(i, &notes_addr, &notes_len) < 0) {
-			/* This cpu is not present. Skip it. */
-			continue;
-		}
+		int ret;
+
+		ret = get_note_info(i, &notes_addr, &notes_len);
 		count_cpu--;
+		if (ret < 0) /* This cpu is not present. Skip it. */
+			continue;
 
 		phdr = (PHDR *) bufp;
 		bufp += sizeof(PHDR);

Thanks
Dave

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