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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: Helge Deller <deller@gmx.de>
This commit is contained in:
Helge Deller 2018-11-10 16:14:59 +01:00
parent 40e020c129
commit 8cc28269b9
5 changed files with 117 additions and 81 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/parisc/include/asm/alternative.h
View File

@ -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:" \

2
arch/parisc/kernel/Makefile
View File

@ -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

98
arch/parisc/kernel/alternative.c Normal file
View File

@ -0,0 +1,98 @@
// 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);
}

14
arch/parisc/kernel/module.c
View File

@ -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;
}

80
arch/parisc/kernel/setup.c
View File

@ -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);