Commit 8404410b authored by Michael Ellerman's avatar Michael Ellerman
Browse files

Merge branch 'topic/livepatch' into next 

Merge the support for live patching on ppc64le using mprofile-kernel.
This branch has also been merged into the livepatching tree for v4.7.
parents 1050e689 85baa095

arch/powerpc/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -160,6 +160,7 @@ config PPC 
	select HAVE_ARCH_SECCOMP_FILTER

	select ARCH_HAS_UBSAN_SANITIZE_ALL

	select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT

	select HAVE_LIVEPATCH if HAVE_DYNAMIC_FTRACE_WITH_REGS



config GENERIC_CSUM

	def_bool CPU_LITTLE_ENDIAN
@@ -1107,3 +1108,5 @@ config PPC_LIB_RHEAP 
	bool



source "arch/powerpc/kvm/Kconfig"



source "kernel/livepatch/Kconfig"

arch/powerpc/include/asm/livepatch.h

0 → 100644
+62 −0
Original line number Diff line number Diff line 
/*

 * livepatch.h - powerpc-specific Kernel Live Patching Core

 *

 * Copyright (C) 2015-2016, SUSE, IBM Corp.

 *

 * 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_POWERPC_LIVEPATCH_H

#define _ASM_POWERPC_LIVEPATCH_H



#include <linux/module.h>

#include <linux/ftrace.h>



#ifdef CONFIG_LIVEPATCH

static inline int klp_check_compiler_support(void)

{

	return 0;

}



static inline int klp_write_module_reloc(struct module *mod, unsigned long

		type, unsigned long loc, unsigned long value)

{

	/* This requires infrastructure changes; we need the loadinfos. */

	return -ENOSYS;

}



static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)

{

	regs->nip = ip;

}



#define klp_get_ftrace_location klp_get_ftrace_location

static inline unsigned long klp_get_ftrace_location(unsigned long faddr)

{

	/*

	 * Live patch works only with -mprofile-kernel on PPC. In this case,

	 * the ftrace location is always within the first 16 bytes.

	 */

	return ftrace_location_range(faddr, faddr + 16);

}



static inline void klp_init_thread_info(struct thread_info *ti)

{

	/* + 1 to account for STACK_END_MAGIC */

	ti->livepatch_sp = (unsigned long *)(ti + 1) + 1;

}

#else

static void klp_init_thread_info(struct thread_info *ti) { }

#endif /* CONFIG_LIVEPATCH */



#endif /* _ASM_POWERPC_LIVEPATCH_H */

arch/powerpc/include/asm/thread_info.h

+3 −1
Original line number Diff line number Diff line
@@ -43,7 +43,9 @@ struct thread_info { 
	int		preempt_count;		/* 0 => preemptable,

						   <0 => BUG */

	unsigned long	local_flags;		/* private flags for thread */



#ifdef CONFIG_LIVEPATCH

	unsigned long *livepatch_sp;

#endif

	/* low level flags - has atomic operations done on it */

	unsigned long	flags ____cacheline_aligned_in_smp;

};

arch/powerpc/kernel/asm-offsets.c

+4 −0
Original line number Diff line number Diff line
@@ -86,6 +86,10 @@ int main(void) 
	DEFINE(KSP_LIMIT, offsetof(struct thread_struct, ksp_limit));

#endif /* CONFIG_PPC64 */



#ifdef CONFIG_LIVEPATCH

	DEFINE(TI_livepatch_sp, offsetof(struct thread_info, livepatch_sp));

#endif



	DEFINE(KSP, offsetof(struct thread_struct, ksp));

	DEFINE(PT_REGS, offsetof(struct thread_struct, regs));

#ifdef CONFIG_BOOKE

arch/powerpc/kernel/entry_64.S

+97 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 


#include <linux/errno.h>

#include <linux/err.h>

#include <linux/magic.h>

#include <asm/unistd.h>

#include <asm/processor.h>

#include <asm/page.h>
@@ -1248,6 +1249,9 @@ _GLOBAL(ftrace_caller) 
	addi	r3,r3,function_trace_op@toc@l

	ld	r5,0(r3)



#ifdef CONFIG_LIVEPATCH

	mr	r14,r7		/* remember old NIP */

#endif

	/* Calculate ip from nip-4 into r3 for call below */

	subi    r3, r7, MCOUNT_INSN_SIZE
@@ -1272,6 +1276,9 @@ ftrace_call: 
	/* Load ctr with the possibly modified NIP */

	ld	r3, _NIP(r1)

	mtctr	r3

#ifdef CONFIG_LIVEPATCH

	cmpd	r14,r3		/* has NIP been altered? */

#endif



	/* Restore gprs */

	REST_8GPRS(0,r1)
@@ -1289,6 +1296,11 @@ ftrace_call: 
	ld	r0, LRSAVE(r1)

	mtlr	r0



#ifdef CONFIG_LIVEPATCH

        /* Based on the cmpd above, if the NIP was altered handle livepatch */

	bne-	livepatch_handler

#endif



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	stdu	r1, -112(r1)

.globl ftrace_graph_call
@@ -1305,6 +1317,91 @@ _GLOBAL(ftrace_graph_stub) 


_GLOBAL(ftrace_stub)

	blr



#ifdef CONFIG_LIVEPATCH

	/*

	 * This function runs in the mcount context, between two functions. As

	 * such it can only clobber registers which are volatile and used in

	 * function linkage.

	 *

	 * We get here when a function A, calls another function B, but B has

	 * been live patched with a new function C.

	 *

	 * On entry:

	 *  - we have no stack frame and can not allocate one

	 *  - LR points back to the original caller (in A)

	 *  - CTR holds the new NIP in C

	 *  - r0 & r12 are free

	 *

	 * r0 can't be used as the base register for a DS-form load or store, so

	 * we temporarily shuffle r1 (stack pointer) into r0 and then put it back.

	 */

livepatch_handler:

	CURRENT_THREAD_INFO(r12, r1)



	/* Save stack pointer into r0 */

	mr	r0, r1



	/* Allocate 3 x 8 bytes */

	ld	r1, TI_livepatch_sp(r12)

	addi	r1, r1, 24

	std	r1, TI_livepatch_sp(r12)



	/* Save toc & real LR on livepatch stack */

	std	r2,  -24(r1)

	mflr	r12

	std	r12, -16(r1)



	/* Store stack end marker */

	lis     r12, STACK_END_MAGIC@h

	ori     r12, r12, STACK_END_MAGIC@l

	std	r12, -8(r1)



	/* Restore real stack pointer */

	mr	r1, r0



	/* Put ctr in r12 for global entry and branch there */

	mfctr	r12

	bctrl



	/*

	 * Now we are returning from the patched function to the original

	 * caller A. We are free to use r0 and r12, and we can use r2 until we

	 * restore it.

	 */



	CURRENT_THREAD_INFO(r12, r1)



	/* Save stack pointer into r0 */

	mr	r0, r1



	ld	r1, TI_livepatch_sp(r12)



	/* Check stack marker hasn't been trashed */

	lis     r2,  STACK_END_MAGIC@h

	ori     r2,  r2, STACK_END_MAGIC@l

	ld	r12, -8(r1)

1:	tdne	r12, r2

	EMIT_BUG_ENTRY 1b, __FILE__, __LINE__ - 1, 0



	/* Restore LR & toc from livepatch stack */

	ld	r12, -16(r1)

	mtlr	r12

	ld	r2,  -24(r1)



	/* Pop livepatch stack frame */

	CURRENT_THREAD_INFO(r12, r0)

	subi	r1, r1, 24

	std	r1, TI_livepatch_sp(r12)



	/* Restore real stack pointer */

	mr	r1, r0



	/* Return to original caller of live patched function */

	blr

#endif





#else

_GLOBAL_TOC(_mcount)

	/* Taken from output of objdump from lib64/glibc */