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Commit 8cc28269 authored by Helge Deller's avatar Helge Deller
Browse files

parisc: Split out alternative live patching code 



Move the alternative implemenation coding to alternative.c and add code to
patch modules while loading.

Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent 40e020c1

arch/parisc/include/asm/alternative.h

+4 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#ifndef __ASM_PARISC_ALTERNATIVE_H

#define __ASM_PARISC_ALTERNATIVE_H



#define ALT_COND_ALWAYS		0x80	/* always replace instruction */

#define ALT_COND_NO_SMP		0x01	/* when running UP instead of SMP */

#define ALT_COND_NO_DCACHE	0x02	/* if system has no d-cache  */

#define ALT_COND_NO_ICACHE	0x04	/* if system has no i-cache  */
@@ -26,6 +27,9 @@ struct alt_instr { 
};



void set_kernel_text_rw(int enable_read_write);

void apply_alternatives_all(void);

void apply_alternatives(struct alt_instr *start, struct alt_instr *end,

	const char *module_name);



/* Alternative SMP implementation. */

#define ALTERNATIVE(cond, replacement)		"!0:"	\

arch/parisc/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ extra-y := head.o vmlinux.lds 


obj-y	     	:= cache.o pacache.o setup.o pdt.o traps.o time.o irq.o \

		   pa7300lc.o syscall.o entry.o sys_parisc.o firmware.o \

		   ptrace.o hardware.o inventory.o drivers.o \

		   ptrace.o hardware.o inventory.o drivers.o alternative.o \

		   signal.o hpmc.o real2.o parisc_ksyms.o unaligned.o \

		   process.o processor.o pdc_cons.o pdc_chassis.o unwind.o

arch/parisc/kernel/alternative.c

0 → 100644
+98 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 *    Alternative live-patching for parisc.

 *    Copyright (C) 2018 Helge Deller <deller@gmx.de>

 *

 */



#include <asm/processor.h>

#include <asm/sections.h>

#include <asm/alternative.h>



#include <linux/module.h>



static int no_alternatives;

static int __init setup_no_alternatives(char *str)

{

	no_alternatives = 1;

	return 1;

}

__setup("no-alternatives", setup_no_alternatives);



void __init_or_module apply_alternatives(struct alt_instr *start,

		 struct alt_instr *end, const char *module_name)

{

	struct alt_instr *entry;

	int index = 0, applied = 0;

	int num_cpus = num_online_cpus();



	for (entry = start; entry < end; entry++, index++) {



		u32 *from, len, cond, replacement;



		from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);

		len = entry->len;

		cond = entry->cond;

		replacement = entry->replacement;



		WARN_ON(!cond);



		if (cond != ALT_COND_ALWAYS && no_alternatives)

			continue;



		pr_debug("Check %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",

			index, cond, len, from, replacement);



		if ((cond & ALT_COND_NO_SMP) && (num_cpus != 1))

			continue;

		if ((cond & ALT_COND_NO_DCACHE) && (cache_info.dc_size != 0))

			continue;

		if ((cond & ALT_COND_NO_ICACHE) && (cache_info.ic_size != 0))

			continue;



		/*

		 * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit

		 * set (bit #61, big endian), we have to flush and sync every

		 * time IO-PDIR is changed in Ike/Astro.

		 */

		if ((cond & ALT_COND_NO_IOC_FDC) &&

			(boot_cpu_data.pdc.capabilities & PDC_MODEL_IOPDIR_FDC))

			continue;



		/* Want to replace pdtlb by a pdtlb,l instruction? */

		if (replacement == INSN_PxTLB) {

			replacement = *from;

			if (boot_cpu_data.cpu_type >= pcxu) /* >= pa2.0 ? */

				replacement |= (1 << 10); /* set el bit */

		}



		/*

		 * Replace instruction with NOPs?

		 * For long distance insert a branch instruction instead.

		 */

		if (replacement == INSN_NOP && len > 1)

			replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */



		pr_debug("Do    %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",

			index, cond, len, from, replacement);



		/* Replace instruction */

		*from = replacement;

		applied++;

	}



	pr_info("%s%salternatives: applied %d out of %d patches\n",

		module_name ? : "", module_name ? " " : "",

		applied, index);

}





void __init apply_alternatives_all(void)

{

	set_kernel_text_rw(1);



	apply_alternatives((struct alt_instr *) &__alt_instructions,

		(struct alt_instr *) &__alt_instructions_end, NULL);



	set_kernel_text_rw(0);

}

arch/parisc/kernel/module.c

+14 −0
Original line number Diff line number Diff line
@@ -877,6 +877,8 @@ int module_finalize(const Elf_Ehdr *hdr, 
	int i;

	unsigned long nsyms;

	const char *strtab = NULL;

	const Elf_Shdr *s;

	char *secstrings;

	Elf_Sym *newptr, *oldptr;

	Elf_Shdr *symhdr = NULL;

#ifdef DEBUG
@@ -948,6 +950,18 @@ int module_finalize(const Elf_Ehdr *hdr, 
	nsyms = newptr - (Elf_Sym *)symhdr->sh_addr;

	DEBUGP("NEW num_symtab %lu\n", nsyms);

	symhdr->sh_size = nsyms * sizeof(Elf_Sym);



	/* find .altinstructions section */

	secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {

		void *aseg = (void *) s->sh_addr;

		char *secname = secstrings + s->sh_name;



		if (!strcmp(".altinstructions", secname))

			/* patch .altinstructions */

			apply_alternatives(aseg, aseg + s->sh_size, me->name);

	}



	return 0;

}

arch/parisc/kernel/setup.c

+0 −80
Original line number Diff line number Diff line
@@ -305,86 +305,6 @@ static int __init parisc_init_resources(void) 
	return 0;

}



static int no_alternatives __initdata;

static int __init setup_no_alternatives(char *str)

{

	no_alternatives = 1;

	return 1;

}

__setup("no-alternatives", setup_no_alternatives);



static void __init apply_alternatives_all(void)

{

	struct alt_instr *entry;

	int index = 0, applied = 0;





	pr_info("alternatives: %spatching kernel code\n",

		no_alternatives ? "NOT " : "");

	if (no_alternatives)

		return;



	set_kernel_text_rw(1);



	for (entry = (struct alt_instr *) &__alt_instructions;

		entry < (struct alt_instr *) &__alt_instructions_end;

		entry++, index++) {



		u32 *from, len, cond, replacement;



		from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);

		len = entry->len;

		cond = entry->cond;

		replacement = entry->replacement;



		WARN_ON(!cond);

		pr_debug("Check %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",

			index, cond, len, from, replacement);



		if ((cond & ALT_COND_NO_SMP) && (num_online_cpus() != 1))

			continue;

		if ((cond & ALT_COND_NO_DCACHE) && (cache_info.dc_size != 0))

			continue;

		if ((cond & ALT_COND_NO_ICACHE) && (cache_info.ic_size != 0))

			continue;



		/*

		 * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit

		 * set (bit #61, big endian), we have to flush and sync every

		 * time IO-PDIR is changed in Ike/Astro.

		 */

		if ((cond & ALT_COND_NO_IOC_FDC) &&

			(boot_cpu_data.pdc.capabilities & PDC_MODEL_IOPDIR_FDC))

			continue;



		/* Want to replace pdtlb by a pdtlb,l instruction? */

		if (replacement == INSN_PxTLB) {

			replacement = *from;

			if (boot_cpu_data.cpu_type >= pcxu) /* >= pa2.0 ? */

				replacement |= (1 << 10); /* set el bit */

		}



		/*

		 * Replace instruction with NOPs?

		 * For long distance insert a branch instruction instead.

		 */

		if (replacement == INSN_NOP && len > 1)

			replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */



		pr_debug("Do    %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",

			index, cond, len, from, replacement);



		/* Replace instruction */

		*from = replacement;

		applied++;

	}



	pr_info("alternatives: applied %d out of %d patches\n", applied, index);



	set_kernel_text_rw(0);

}





extern void gsc_init(void);

extern void processor_init(void);

extern void ccio_init(void);