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Commit 62217beb authored by Helge Deller's avatar Helge Deller
Browse files

parisc: Add static branch and JUMP_LABEL feature 



Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent bdca5d64

arch/parisc/Kconfig

+2 −0
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@@ -45,6 +45,8 @@ config PARISC 
	select HAVE_DEBUG_STACKOVERFLOW

	select HAVE_ARCH_AUDITSYSCALL

	select HAVE_ARCH_HASH

	select HAVE_ARCH_JUMP_LABEL

	select HAVE_ARCH_JUMP_LABEL_RELATIVE

	select HAVE_ARCH_SECCOMP_FILTER

	select HAVE_ARCH_TRACEHOOK

	select HAVE_REGS_AND_STACK_ACCESS_API

arch/parisc/include/asm/jump_label.h

0 → 100644
+43 −0
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/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _ASM_PARISC_JUMP_LABEL_H

#define _ASM_PARISC_JUMP_LABEL_H



#ifndef __ASSEMBLY__



#include <linux/types.h>

#include <asm/assembly.h>



#define JUMP_LABEL_NOP_SIZE 4



static __always_inline bool arch_static_branch(struct static_key *key, bool branch)

{

	asm_volatile_goto("1:\n\t"

		 "nop\n\t"

		 ".pushsection __jump_table,  \"aw\"\n\t"

		 ".word 1b - ., %l[l_yes] - .\n\t"

		 __stringify(ASM_ULONG_INSN) " %c0 - .\n\t"

		 ".popsection\n\t"

		 : :  "i" (&((char *)key)[branch]) :  : l_yes);



	return false;

l_yes:

	return true;

}



static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)

{

	asm_volatile_goto("1:\n\t"

		 "b,n %l[l_yes]\n\t"

		 ".pushsection __jump_table,  \"aw\"\n\t"

		 ".word 1b - ., %l[l_yes] - .\n\t"

		 __stringify(ASM_ULONG_INSN) " %c0 - .\n\t"

		 ".popsection\n\t"

		 : :  "i" (&((char *)key)[branch]) :  : l_yes);



	return false;

l_yes:

	return true;

}



#endif  /* __ASSEMBLY__ */

#endif

arch/parisc/kernel/Makefile

+1 −0
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@@ -33,5 +33,6 @@ obj-$(CONFIG_64BIT) += perf.o perf_asm.o $(obj64-y) 
obj-$(CONFIG_PARISC_CPU_TOPOLOGY)	+= topology.o

obj-$(CONFIG_FUNCTION_TRACER)		+= ftrace.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o

obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o

obj-$(CONFIG_KGDB)			+= kgdb.o

obj-$(CONFIG_KPROBES)			+= kprobes.o

arch/parisc/kernel/jump_label.c

0 → 100644
+55 −0
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// SPDX-License-Identifier: GPL-2.0+

/*

 * Copyright (C) 2019 Helge Deller <deller@gmx.de>

 *

 * Based on arch/arm64/kernel/jump_label.c

 */

#include <linux/kernel.h>

#include <linux/jump_label.h>

#include <linux/bug.h>

#include <asm/alternative.h>

#include <asm/patch.h>



static inline int reassemble_17(int as17)

{

	return (((as17 & 0x10000) >> 16) |

		((as17 & 0x0f800) << 5) |

		((as17 & 0x00400) >> 8) |

		((as17 & 0x003ff) << 3));

}



void arch_jump_label_transform(struct jump_entry *entry,

			       enum jump_label_type type)

{

	void *addr = (void *)jump_entry_code(entry);

	u32 insn;



	if (type == JUMP_LABEL_JMP) {

		void *target = (void *)jump_entry_target(entry);

		int distance = target - addr;

		/*

		 * Encode the PA1.1 "b,n" instruction with a 17-bit

		 * displacement.  In case we hit the BUG(), we could use

		 * another branch instruction with a 22-bit displacement on

		 * 64-bit CPUs instead. But this seems sufficient for now.

		 */

		distance -= 8;

		BUG_ON(distance > 262143 || distance < -262144);

		insn = 0xe8000002 | reassemble_17(distance >> 2);

	} else {

		insn = INSN_NOP;

	}



	patch_text(addr, insn);

}



void arch_jump_label_transform_static(struct jump_entry *entry,

				      enum jump_label_type type)

{

	/*

	 * We use the architected NOP in arch_static_branch, so there's no

	 * need to patch an identical NOP over the top of it here. The core

	 * will call arch_jump_label_transform from a module notifier if the

	 * NOP needs to be replaced by a branch.

	 */

}

arch/parisc/kernel/vmlinux.lds.S

+3 −0
Original line number Diff line number Diff line
@@ -18,6 +18,9 @@ 
				*(.data..vm0.pgd) \

				*(.data..vm0.pte)



/* No __ro_after_init data in the .rodata section - which will always be ro */

#define RO_AFTER_INIT_DATA



#include <asm-generic/vmlinux.lds.h>



/* needed for the processor specific cache alignment size */