diff mbox

[1/7] arm: Add livepatch arch specific code

Message ID 1481043967-15602-2-git-send-email-abelvesa@linux.com (mailing list archive)
State New, archived
Headers show

Commit Message

Abel Vesa Dec. 6, 2016, 5:06 p.m. UTC 
klp_get_ftrace_location is used by ftrace to get the entry for a
specific function from the mcount list. klp_arch_set_pc is used
to set the pc from the regs passed as an argument to the
ftrace_ops_no_ops function to the starting address of the patched
function. klp_write_module_reloc is not doing anything at this
moment.

Signed-off-by: Abel Vesa <abelvesa@linux.com>
---
 MAINTAINERS                      |  3 +++
 arch/arm/include/asm/livepatch.h | 46 ++++++++++++++++++++++++++++++++++++++++
 arch/arm/kernel/livepatch.c      | 43 +++++++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 arch/arm/include/asm/livepatch.h
 create mode 100644 arch/arm/kernel/livepatch.c

Comments

Miroslav Benes Jan. 16, 2017, 4:47 p.m. UTC | #1 
On Tue, 6 Dec 2016, Abel Vesa wrote:

> klp_get_ftrace_location is used by ftrace to get the entry for a
> specific function from the mcount list. klp_arch_set_pc is used
> to set the pc from the regs passed as an argument to the
> ftrace_ops_no_ops function to the starting address of the patched
> function. klp_write_module_reloc is not doing anything at this
> moment.
> 
> Signed-off-by: Abel Vesa <abelvesa@linux.com>
> ---
>  MAINTAINERS                      |  3 +++
>  arch/arm/include/asm/livepatch.h | 46 ++++++++++++++++++++++++++++++++++++++++
>  arch/arm/kernel/livepatch.c      | 43 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 92 insertions(+)
>  create mode 100644 arch/arm/include/asm/livepatch.h
>  create mode 100644 arch/arm/kernel/livepatch.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index bd182a1..d43b790 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7466,12 +7466,15 @@ M:	Josh Poimboeuf <jpoimboe@redhat.com>
>  M:	Jessica Yu <jeyu@redhat.com>
>  M:	Jiri Kosina <jikos@kernel.org>
>  M:	Miroslav Benes <mbenes@suse.cz>
> +M:	Abel Vesa <abelvesa@linux.com>
>  R:	Petr Mladek <pmladek@suse.com>
>  S:	Maintained
>  F:	kernel/livepatch/
>  F:	include/linux/livepatch.h
>  F:	arch/x86/include/asm/livepatch.h
>  F:	arch/x86/kernel/livepatch.c
> +F:	arch/arm/include/asm/livepatch.h
> +F:	arch/arm/kernel/livepatch.c
>  F:	Documentation/livepatch/
>  F:	Documentation/ABI/testing/sysfs-kernel-livepatch
>  F:	samples/livepatch/

Thanks for the offer but I think we manage quite well ;)

> diff --git a/arch/arm/include/asm/livepatch.h b/arch/arm/include/asm/livepatch.h
> new file mode 100644
> index 0000000..d4e3ff0
> --- /dev/null
> +++ b/arch/arm/include/asm/livepatch.h
> @@ -0,0 +1,46 @@
> +/*
> + * livepatch.h - arm specific Kernel Live Patching Core
> + *
> + * Copyright (C) 2016 Abel Vesa <abelvesa@linux.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef _ASM_ARM_LIVEPATCH_H
> +#define _ASM_ARM_LIVEPATCH_H
> +
> +#include <asm/setup.h>
> +#include <linux/module.h>
> +#include <linux/ftrace.h>
> +
> +static inline int klp_check_compiler_support(void)
> +{
> +	return 0;
> +}
> +
> +int klp_write_module_reloc(struct module *mod, unsigned long type,
> +			   unsigned long loc, unsigned long value);

This is not needed. See below.

> +
> +static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
> +{
> +	regs->uregs[15] = ip;
> +}
> +
> +#define klp_get_ftrace_location klp_get_ftrace_location
> +static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
> +{
> +	return ftrace_location_range(faddr, faddr + 24);

Comment here about +24 would be great. See similar in powerpc header file.

> +}
> +
> +#endif /* _ASM_ARM_LIVEPATCH_H */
> diff --git a/arch/arm/kernel/livepatch.c b/arch/arm/kernel/livepatch.c
> new file mode 100644
> index 0000000..0656cd6
> --- /dev/null
> +++ b/arch/arm/kernel/livepatch.c
> @@ -0,0 +1,43 @@
> +/*
> + * livepatch.c - arm specific Kernel Live Patching Core
> + *
> + * Copyright (C) 2016 Abel Vesa <abelvesa@linux.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/uaccess.h>
> +#include <linux/ftrace.h>
> +#include <asm/elf.h>
> +#include <asm/livepatch.h>
> +#include <asm/insn.h>
> +#include <asm/ftrace.h>
> +
> +/**
> + * klp_write_module_reloc() - write a relocation in a module
> + * @mod:	module in which the section to be modified is found
> + * @type:	ELF relocation type (see asm/elf.h)
> + * @loc:	address that the relocation should be written to
> + * @value:	relocation value (sym address + addend)
> + *
> + * This function writes a relocation to the specified location for
> + * a particular module.
> + */
> +int klp_write_module_reloc(struct module *mod, unsigned long type,
> +			   unsigned long loc, unsigned long value)
> +{
> +	/* Not implemented yet */
> +	return 0;
> +}

This whole file is not needed. Livepatching uses kernel's internal 
apply_relocate_add() for dealing with relocations. The only thing you need 
to do is to make sure that all needed arch-specific info is preserved 
during a module loading. Specifically mod_arch_specific structure needs to 
be examined in this respect.

See commit f31e0960f395 ("module: s390: keep mod_arch_specific for 
livepatch modules") for s390 case.

But apply_relocate_add() is not implemented on arm yet. I guess it would 
nice to have it... otherwise we could get to an unpleasant situation. 
Livepatch module can rely on its livepatching relocations (that is, there 
are some). apply_relocate_add() returns 0 on arm, so everything seems to 
be nice and then boom some time later.

The question is what happens with normal modules. There are no SHT_RELA 
records probably.

Miroslav
Jessica Yu Jan. 17, 2017, 12:22 a.m. UTC | #2 
+++ Miroslav Benes [16/01/17 17:47 +0100]:
>On Tue, 6 Dec 2016, Abel Vesa wrote:
>
>> klp_get_ftrace_location is used by ftrace to get the entry for a
>> specific function from the mcount list. klp_arch_set_pc is used
>> to set the pc from the regs passed as an argument to the
>> ftrace_ops_no_ops function to the starting address of the patched
>> function. klp_write_module_reloc is not doing anything at this
>> moment.
>>
>> Signed-off-by: Abel Vesa <abelvesa@linux.com>
>> ---
>>  MAINTAINERS                      |  3 +++
>>  arch/arm/include/asm/livepatch.h | 46 ++++++++++++++++++++++++++++++++++++++++
>>  arch/arm/kernel/livepatch.c      | 43 +++++++++++++++++++++++++++++++++++++
>>  3 files changed, 92 insertions(+)
>>  create mode 100644 arch/arm/include/asm/livepatch.h
>>  create mode 100644 arch/arm/kernel/livepatch.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index bd182a1..d43b790 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -7466,12 +7466,15 @@ M:	Josh Poimboeuf <jpoimboe@redhat.com>
>>  M:	Jessica Yu <jeyu@redhat.com>
>>  M:	Jiri Kosina <jikos@kernel.org>
>>  M:	Miroslav Benes <mbenes@suse.cz>
>> +M:	Abel Vesa <abelvesa@linux.com>
>>  R:	Petr Mladek <pmladek@suse.com>
>>  S:	Maintained
>>  F:	kernel/livepatch/
>>  F:	include/linux/livepatch.h
>>  F:	arch/x86/include/asm/livepatch.h
>>  F:	arch/x86/kernel/livepatch.c
>> +F:	arch/arm/include/asm/livepatch.h
>> +F:	arch/arm/kernel/livepatch.c
>>  F:	Documentation/livepatch/
>>  F:	Documentation/ABI/testing/sysfs-kernel-livepatch
>>  F:	samples/livepatch/
>
>Thanks for the offer but I think we manage quite well ;)
>
>> diff --git a/arch/arm/include/asm/livepatch.h b/arch/arm/include/asm/livepatch.h
>> new file mode 100644
>> index 0000000..d4e3ff0
>> --- /dev/null
>> +++ b/arch/arm/include/asm/livepatch.h
>> @@ -0,0 +1,46 @@
>> +/*
>> + * livepatch.h - arm specific Kernel Live Patching Core
>> + *
>> + * Copyright (C) 2016 Abel Vesa <abelvesa@linux.com>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License
>> + * as published by the Free Software Foundation; either version 2
>> + * of the License, or (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#ifndef _ASM_ARM_LIVEPATCH_H
>> +#define _ASM_ARM_LIVEPATCH_H
>> +
>> +#include <asm/setup.h>
>> +#include <linux/module.h>
>> +#include <linux/ftrace.h>
>> +
>> +static inline int klp_check_compiler_support(void)
>> +{
>> +	return 0;
>> +}
>> +
>> +int klp_write_module_reloc(struct module *mod, unsigned long type,
>> +			   unsigned long loc, unsigned long value);
>
>This is not needed. See below.
>
>> +
>> +static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
>> +{
>> +	regs->uregs[15] = ip;
>> +}
>> +
>> +#define klp_get_ftrace_location klp_get_ftrace_location
>> +static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
>> +{
>> +	return ftrace_location_range(faddr, faddr + 24);
>
>Comment here about +24 would be great. See similar in powerpc header file.
>
>> +}
>> +
>> +#endif /* _ASM_ARM_LIVEPATCH_H */
>> diff --git a/arch/arm/kernel/livepatch.c b/arch/arm/kernel/livepatch.c
>> new file mode 100644
>> index 0000000..0656cd6
>> --- /dev/null
>> +++ b/arch/arm/kernel/livepatch.c
>> @@ -0,0 +1,43 @@
>> +/*
>> + * livepatch.c - arm specific Kernel Live Patching Core
>> + *
>> + * Copyright (C) 2016 Abel Vesa <abelvesa@linux.com>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License
>> + * as published by the Free Software Foundation; either version 2
>> + * of the License, or (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/uaccess.h>
>> +#include <linux/ftrace.h>
>> +#include <asm/elf.h>
>> +#include <asm/livepatch.h>
>> +#include <asm/insn.h>
>> +#include <asm/ftrace.h>
>> +
>> +/**
>> + * klp_write_module_reloc() - write a relocation in a module
>> + * @mod:	module in which the section to be modified is found
>> + * @type:	ELF relocation type (see asm/elf.h)
>> + * @loc:	address that the relocation should be written to
>> + * @value:	relocation value (sym address + addend)
>> + *
>> + * This function writes a relocation to the specified location for
>> + * a particular module.
>> + */
>> +int klp_write_module_reloc(struct module *mod, unsigned long type,
>> +			   unsigned long loc, unsigned long value)
>> +{
>> +	/* Not implemented yet */
>> +	return 0;
>> +}
>
>This whole file is not needed. Livepatching uses kernel's internal
>apply_relocate_add() for dealing with relocations. The only thing you need
>to do is to make sure that all needed arch-specific info is preserved
>during a module loading. Specifically mod_arch_specific structure needs to
>be examined in this respect.

Yup. Since we rely on apply_relocate_add() to apply relocations, just
make sure that you preserve anything (e.g., plt tables) you need to
make that call post-module init. In the case of s390, we needed to
make sure we kept mod->arch.syminfo, so that the call to
apply_relocate_add() would succeed.

>But apply_relocate_add() is not implemented on arm yet. I guess it would
>nice to have it... otherwise we could get to an unpleasant situation.
>Livepatch module can rely on its livepatching relocations (that is, there
>are some). apply_relocate_add() returns 0 on arm, so everything seems to
>be nice and then boom some time later.

Doesn't it return -ENOEXEC? MODULES_USE_ELF_RELA is not defined
on arm, I think (see moduleloader.h).

>The question is what happens with normal modules. There are no SHT_RELA
>records probably.

For arm, I think there are only SHT_REL relocation sections
(MODULES_USE_ELF_REL is set instead of MODULES_USE_ELF_RELA), so
during apply_relocations() in load_module(), only apply_relocate()
should be called, and not apply_relocate_add().

Hm, I guess that means if we want livepatch support for the
architectures that don't support RELA relocations, we would have to
check if the section is SHT_REL or SHT_RELA before calling the right
apply_relocate* function.

Jessica
Jessica Yu Jan. 17, 2017, 2:27 a.m. UTC | #3 
+++ Jessica Yu [16/01/17 19:22 -0500]:
>+++ Miroslav Benes [16/01/17 17:47 +0100]:
>>On Tue, 6 Dec 2016, Abel Vesa wrote:
>>
>>>klp_get_ftrace_location is used by ftrace to get the entry for a
>>>specific function from the mcount list. klp_arch_set_pc is used
>>>to set the pc from the regs passed as an argument to the
>>>ftrace_ops_no_ops function to the starting address of the patched
>>>function. klp_write_module_reloc is not doing anything at this
>>>moment.
>>>
>>>Signed-off-by: Abel Vesa <abelvesa@linux.com>
>>>---
>>> MAINTAINERS                      |  3 +++
>>> arch/arm/include/asm/livepatch.h | 46 ++++++++++++++++++++++++++++++++++++++++
>>> arch/arm/kernel/livepatch.c      | 43 +++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 92 insertions(+)
>>> create mode 100644 arch/arm/include/asm/livepatch.h
>>> create mode 100644 arch/arm/kernel/livepatch.c
>>>
>>>diff --git a/MAINTAINERS b/MAINTAINERS
>>>index bd182a1..d43b790 100644
>>>--- a/MAINTAINERS
>>>+++ b/MAINTAINERS
>>>@@ -7466,12 +7466,15 @@ M:	Josh Poimboeuf <jpoimboe@redhat.com>
>>> M:	Jessica Yu <jeyu@redhat.com>
>>> M:	Jiri Kosina <jikos@kernel.org>
>>> M:	Miroslav Benes <mbenes@suse.cz>
>>>+M:	Abel Vesa <abelvesa@linux.com>
>>> R:	Petr Mladek <pmladek@suse.com>
>>> S:	Maintained
>>> F:	kernel/livepatch/
>>> F:	include/linux/livepatch.h
>>> F:	arch/x86/include/asm/livepatch.h
>>> F:	arch/x86/kernel/livepatch.c
>>>+F:	arch/arm/include/asm/livepatch.h
>>>+F:	arch/arm/kernel/livepatch.c
>>> F:	Documentation/livepatch/
>>> F:	Documentation/ABI/testing/sysfs-kernel-livepatch
>>> F:	samples/livepatch/
>>
>>Thanks for the offer but I think we manage quite well ;)
>>
>>>diff --git a/arch/arm/include/asm/livepatch.h b/arch/arm/include/asm/livepatch.h
>>>new file mode 100644
>>>index 0000000..d4e3ff0
>>>--- /dev/null
>>>+++ b/arch/arm/include/asm/livepatch.h
>>>@@ -0,0 +1,46 @@
>>>+/*
>>>+ * livepatch.h - arm specific Kernel Live Patching Core
>>>+ *
>>>+ * Copyright (C) 2016 Abel Vesa <abelvesa@linux.com>
>>>+ *
>>>+ * This program is free software; you can redistribute it and/or
>>>+ * modify it under the terms of the GNU General Public License
>>>+ * as published by the Free Software Foundation; either version 2
>>>+ * of the License, or (at your option) any later version.
>>>+ *
>>>+ * This program is distributed in the hope that it will be useful,
>>>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>>+ * GNU General Public License for more details.
>>>+ *
>>>+ * You should have received a copy of the GNU General Public License
>>>+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
>>>+ */
>>>+
>>>+#ifndef _ASM_ARM_LIVEPATCH_H
>>>+#define _ASM_ARM_LIVEPATCH_H
>>>+
>>>+#include <asm/setup.h>
>>>+#include <linux/module.h>
>>>+#include <linux/ftrace.h>
>>>+
>>>+static inline int klp_check_compiler_support(void)
>>>+{
>>>+	return 0;
>>>+}
>>>+
>>>+int klp_write_module_reloc(struct module *mod, unsigned long type,
>>>+			   unsigned long loc, unsigned long value);
>>
>>This is not needed. See below.
>>
>>>+
>>>+static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
>>>+{
>>>+	regs->uregs[15] = ip;
>>>+}
>>>+
>>>+#define klp_get_ftrace_location klp_get_ftrace_location
>>>+static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
>>>+{
>>>+	return ftrace_location_range(faddr, faddr + 24);
>>
>>Comment here about +24 would be great. See similar in powerpc header file.
>>
>>>+}
>>>+
>>>+#endif /* _ASM_ARM_LIVEPATCH_H */
>>>diff --git a/arch/arm/kernel/livepatch.c b/arch/arm/kernel/livepatch.c
>>>new file mode 100644
>>>index 0000000..0656cd6
>>>--- /dev/null
>>>+++ b/arch/arm/kernel/livepatch.c
>>>@@ -0,0 +1,43 @@
>>>+/*
>>>+ * livepatch.c - arm specific Kernel Live Patching Core
>>>+ *
>>>+ * Copyright (C) 2016 Abel Vesa <abelvesa@linux.com>
>>>+ *
>>>+ * This program is free software; you can redistribute it and/or
>>>+ * modify it under the terms of the GNU General Public License
>>>+ * as published by the Free Software Foundation; either version 2
>>>+ * of the License, or (at your option) any later version.
>>>+ *
>>>+ * This program is distributed in the hope that it will be useful,
>>>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>>+ * GNU General Public License for more details.
>>>+ *
>>>+ * You should have received a copy of the GNU General Public License
>>>+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
>>>+ */
>>>+
>>>+#include <linux/module.h>
>>>+#include <linux/uaccess.h>
>>>+#include <linux/ftrace.h>
>>>+#include <asm/elf.h>
>>>+#include <asm/livepatch.h>
>>>+#include <asm/insn.h>
>>>+#include <asm/ftrace.h>
>>>+
>>>+/**
>>>+ * klp_write_module_reloc() - write a relocation in a module
>>>+ * @mod:	module in which the section to be modified is found
>>>+ * @type:	ELF relocation type (see asm/elf.h)
>>>+ * @loc:	address that the relocation should be written to
>>>+ * @value:	relocation value (sym address + addend)
>>>+ *
>>>+ * This function writes a relocation to the specified location for
>>>+ * a particular module.
>>>+ */
>>>+int klp_write_module_reloc(struct module *mod, unsigned long type,
>>>+			   unsigned long loc, unsigned long value)
>>>+{
>>>+	/* Not implemented yet */
>>>+	return 0;
>>>+}
>>
>>This whole file is not needed. Livepatching uses kernel's internal
>>apply_relocate_add() for dealing with relocations. The only thing you need
>>to do is to make sure that all needed arch-specific info is preserved
>>during a module loading. Specifically mod_arch_specific structure needs to
>>be examined in this respect.
>
>Yup. Since we rely on apply_relocate_add() to apply relocations, just
>make sure that you preserve anything (e.g., plt tables) you need to
>make that call post-module init. In the case of s390, we needed to
>make sure we kept mod->arch.syminfo, so that the call to
>apply_relocate_add() would succeed.
>
>>But apply_relocate_add() is not implemented on arm yet. I guess it would
>>nice to have it... otherwise we could get to an unpleasant situation.
>>Livepatch module can rely on its livepatching relocations (that is, there
>>are some). apply_relocate_add() returns 0 on arm, so everything seems to
>>be nice and then boom some time later.
>
>Doesn't it return -ENOEXEC? MODULES_USE_ELF_RELA is not defined
>on arm, I think (see moduleloader.h).

...And I should have looked at the whole patchset first before
replying :-) I see now that a placeholder was added in patch 3/7.

Jessica
Miroslav Benes Jan. 17, 2017, 1:53 p.m. UTC | #4 
> > But apply_relocate_add() is not implemented on arm yet. I guess it would
> > nice to have it... otherwise we could get to an unpleasant situation.
> > Livepatch module can rely on its livepatching relocations (that is, there
> > are some). apply_relocate_add() returns 0 on arm, so everything seems to
> > be nice and then boom some time later.
> 
> Doesn't it return -ENOEXEC? MODULES_USE_ELF_RELA is not defined
> on arm, I think (see moduleloader.h).

You're right. It confused me too.
 
> > The question is what happens with normal modules. There are no SHT_RELA
> > records probably.
> 
> For arm, I think there are only SHT_REL relocation sections
> (MODULES_USE_ELF_REL is set instead of MODULES_USE_ELF_RELA), so
> during apply_relocations() in load_module(), only apply_relocate()
> should be called, and not apply_relocate_add().

True.

> Hm, I guess that means if we want livepatch support for the
> architectures that don't support RELA relocations, we would have to
> check if the section is SHT_REL or SHT_RELA before calling the right
> apply_relocate* function.

Agreed.

Miroslav
diff mbox

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index bd182a1..d43b790 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7466,12 +7466,15 @@  M:	Josh Poimboeuf <jpoimboe@redhat.com>
 M:	Jessica Yu <jeyu@redhat.com>
 M:	Jiri Kosina <jikos@kernel.org>
 M:	Miroslav Benes <mbenes@suse.cz>
+M:	Abel Vesa <abelvesa@linux.com>
 R:	Petr Mladek <pmladek@suse.com>
 S:	Maintained
 F:	kernel/livepatch/
 F:	include/linux/livepatch.h
 F:	arch/x86/include/asm/livepatch.h
 F:	arch/x86/kernel/livepatch.c
+F:	arch/arm/include/asm/livepatch.h
+F:	arch/arm/kernel/livepatch.c
 F:	Documentation/livepatch/
 F:	Documentation/ABI/testing/sysfs-kernel-livepatch
 F:	samples/livepatch/
diff --git a/arch/arm/include/asm/livepatch.h b/arch/arm/include/asm/livepatch.h
new file mode 100644
index 0000000..d4e3ff0
--- /dev/null
+++ b/arch/arm/include/asm/livepatch.h
@@ -0,0 +1,46 @@ 
+/*
+ * livepatch.h - arm specific Kernel Live Patching Core
+ *
+ * Copyright (C) 2016 Abel Vesa <abelvesa@linux.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _ASM_ARM_LIVEPATCH_H
+#define _ASM_ARM_LIVEPATCH_H
+
+#include <asm/setup.h>
+#include <linux/module.h>
+#include <linux/ftrace.h>
+
+static inline int klp_check_compiler_support(void)
+{
+	return 0;
+}
+
+int klp_write_module_reloc(struct module *mod, unsigned long type,
+			   unsigned long loc, unsigned long value);
+
+static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
+{
+	regs->uregs[15] = ip;
+}
+
+#define klp_get_ftrace_location klp_get_ftrace_location
+static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
+{
+	return ftrace_location_range(faddr, faddr + 24);
+}
+
+#endif /* _ASM_ARM_LIVEPATCH_H */
diff --git a/arch/arm/kernel/livepatch.c b/arch/arm/kernel/livepatch.c
new file mode 100644
index 0000000..0656cd6
--- /dev/null
+++ b/arch/arm/kernel/livepatch.c
@@ -0,0 +1,43 @@ 
+/*
+ * livepatch.c - arm specific Kernel Live Patching Core
+ *
+ * Copyright (C) 2016 Abel Vesa <abelvesa@linux.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <asm/elf.h>
+#include <asm/livepatch.h>
+#include <asm/insn.h>
+#include <asm/ftrace.h>
+
+/**
+ * klp_write_module_reloc() - write a relocation in a module
+ * @mod:	module in which the section to be modified is found
+ * @type:	ELF relocation type (see asm/elf.h)
+ * @loc:	address that the relocation should be written to
+ * @value:	relocation value (sym address + addend)
+ *
+ * This function writes a relocation to the specified location for
+ * a particular module.
+ */
+int klp_write_module_reloc(struct module *mod, unsigned long type,
+			   unsigned long loc, unsigned long value)
+{
+	/* Not implemented yet */
+	return 0;
+}