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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Linus Torvalds](/assets/img/avatar_default.png)
* 'x86-alternatives-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, suspend: Avoid unnecessary smp alternatives switch during suspend/resume * 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86-64, asm: Use fxsaveq/fxrestorq in more places * 'x86-hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, hwmon: Add core threshold notification to therm_throt.c * 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, paravirt: Use native_halt on a halt, not native_safe_halt * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: locking, lockdep: Convert sprintf_symbol to %pS * 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: irq: Better struct irqaction layout
701 lines
18 KiB
C
701 lines
18 KiB
C
#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/mutex.h>
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#include <linux/list.h>
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#include <linux/stringify.h>
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#include <linux/kprobes.h>
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#include <linux/mm.h>
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#include <linux/vmalloc.h>
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#include <linux/memory.h>
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#include <linux/stop_machine.h>
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#include <linux/slab.h>
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#include <asm/alternative.h>
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#include <asm/sections.h>
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#include <asm/pgtable.h>
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#include <asm/mce.h>
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#include <asm/nmi.h>
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#include <asm/vsyscall.h>
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#include <asm/cacheflush.h>
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#include <asm/tlbflush.h>
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#include <asm/io.h>
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#include <asm/fixmap.h>
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#define MAX_PATCH_LEN (255-1)
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#ifdef CONFIG_HOTPLUG_CPU
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static int smp_alt_once;
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static int __init bootonly(char *str)
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{
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smp_alt_once = 1;
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return 1;
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}
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__setup("smp-alt-boot", bootonly);
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#else
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#define smp_alt_once 1
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#endif
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static int __initdata_or_module debug_alternative;
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static int __init debug_alt(char *str)
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{
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debug_alternative = 1;
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return 1;
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}
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__setup("debug-alternative", debug_alt);
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static int noreplace_smp;
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static int __init setup_noreplace_smp(char *str)
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{
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noreplace_smp = 1;
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return 1;
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}
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__setup("noreplace-smp", setup_noreplace_smp);
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#ifdef CONFIG_PARAVIRT
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static int __initdata_or_module noreplace_paravirt = 0;
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static int __init setup_noreplace_paravirt(char *str)
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{
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noreplace_paravirt = 1;
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return 1;
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}
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__setup("noreplace-paravirt", setup_noreplace_paravirt);
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#endif
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#define DPRINTK(fmt, args...) if (debug_alternative) \
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printk(KERN_DEBUG fmt, args)
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#if defined(GENERIC_NOP1) && !defined(CONFIG_X86_64)
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/* Use inline assembly to define this because the nops are defined
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as inline assembly strings in the include files and we cannot
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get them easily into strings. */
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asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nintelnops: "
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GENERIC_NOP1 GENERIC_NOP2 GENERIC_NOP3 GENERIC_NOP4 GENERIC_NOP5 GENERIC_NOP6
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GENERIC_NOP7 GENERIC_NOP8
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"\t.previous");
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extern const unsigned char intelnops[];
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static const unsigned char *const __initconst_or_module
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intel_nops[ASM_NOP_MAX+1] = {
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NULL,
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intelnops,
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intelnops + 1,
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intelnops + 1 + 2,
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intelnops + 1 + 2 + 3,
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intelnops + 1 + 2 + 3 + 4,
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intelnops + 1 + 2 + 3 + 4 + 5,
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intelnops + 1 + 2 + 3 + 4 + 5 + 6,
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intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
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};
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#endif
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#ifdef K8_NOP1
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asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nk8nops: "
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K8_NOP1 K8_NOP2 K8_NOP3 K8_NOP4 K8_NOP5 K8_NOP6
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K8_NOP7 K8_NOP8
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"\t.previous");
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extern const unsigned char k8nops[];
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static const unsigned char *const __initconst_or_module
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k8_nops[ASM_NOP_MAX+1] = {
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NULL,
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k8nops,
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k8nops + 1,
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k8nops + 1 + 2,
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k8nops + 1 + 2 + 3,
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k8nops + 1 + 2 + 3 + 4,
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k8nops + 1 + 2 + 3 + 4 + 5,
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k8nops + 1 + 2 + 3 + 4 + 5 + 6,
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k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
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};
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#endif
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#if defined(K7_NOP1) && !defined(CONFIG_X86_64)
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asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nk7nops: "
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K7_NOP1 K7_NOP2 K7_NOP3 K7_NOP4 K7_NOP5 K7_NOP6
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K7_NOP7 K7_NOP8
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"\t.previous");
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extern const unsigned char k7nops[];
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static const unsigned char *const __initconst_or_module
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k7_nops[ASM_NOP_MAX+1] = {
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NULL,
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k7nops,
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k7nops + 1,
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k7nops + 1 + 2,
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k7nops + 1 + 2 + 3,
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k7nops + 1 + 2 + 3 + 4,
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k7nops + 1 + 2 + 3 + 4 + 5,
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k7nops + 1 + 2 + 3 + 4 + 5 + 6,
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k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
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};
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#endif
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#ifdef P6_NOP1
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asm("\t" __stringify(__INITRODATA_OR_MODULE) "\np6nops: "
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P6_NOP1 P6_NOP2 P6_NOP3 P6_NOP4 P6_NOP5 P6_NOP6
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P6_NOP7 P6_NOP8
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"\t.previous");
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extern const unsigned char p6nops[];
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static const unsigned char *const __initconst_or_module
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p6_nops[ASM_NOP_MAX+1] = {
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NULL,
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p6nops,
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p6nops + 1,
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p6nops + 1 + 2,
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p6nops + 1 + 2 + 3,
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p6nops + 1 + 2 + 3 + 4,
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p6nops + 1 + 2 + 3 + 4 + 5,
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p6nops + 1 + 2 + 3 + 4 + 5 + 6,
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p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
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};
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#endif
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#ifdef CONFIG_X86_64
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extern char __vsyscall_0;
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static const unsigned char *const *__init_or_module find_nop_table(void)
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{
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if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
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boot_cpu_has(X86_FEATURE_NOPL))
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return p6_nops;
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else
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return k8_nops;
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}
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#else /* CONFIG_X86_64 */
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static const unsigned char *const *__init_or_module find_nop_table(void)
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{
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if (boot_cpu_has(X86_FEATURE_K8))
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return k8_nops;
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else if (boot_cpu_has(X86_FEATURE_K7))
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return k7_nops;
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else if (boot_cpu_has(X86_FEATURE_NOPL))
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return p6_nops;
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else
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return intel_nops;
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}
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#endif /* CONFIG_X86_64 */
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/* Use this to add nops to a buffer, then text_poke the whole buffer. */
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static void __init_or_module add_nops(void *insns, unsigned int len)
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{
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const unsigned char *const *noptable = find_nop_table();
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while (len > 0) {
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unsigned int noplen = len;
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if (noplen > ASM_NOP_MAX)
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noplen = ASM_NOP_MAX;
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memcpy(insns, noptable[noplen], noplen);
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insns += noplen;
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len -= noplen;
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}
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}
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extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
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extern s32 __smp_locks[], __smp_locks_end[];
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void *text_poke_early(void *addr, const void *opcode, size_t len);
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/* Replace instructions with better alternatives for this CPU type.
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This runs before SMP is initialized to avoid SMP problems with
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self modifying code. This implies that assymetric systems where
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APs have less capabilities than the boot processor are not handled.
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Tough. Make sure you disable such features by hand. */
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void __init_or_module apply_alternatives(struct alt_instr *start,
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struct alt_instr *end)
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{
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struct alt_instr *a;
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u8 insnbuf[MAX_PATCH_LEN];
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DPRINTK("%s: alt table %p -> %p\n", __func__, start, end);
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for (a = start; a < end; a++) {
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u8 *instr = a->instr;
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BUG_ON(a->replacementlen > a->instrlen);
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BUG_ON(a->instrlen > sizeof(insnbuf));
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BUG_ON(a->cpuid >= NCAPINTS*32);
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if (!boot_cpu_has(a->cpuid))
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continue;
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#ifdef CONFIG_X86_64
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/* vsyscall code is not mapped yet. resolve it manually. */
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if (instr >= (u8 *)VSYSCALL_START && instr < (u8*)VSYSCALL_END) {
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instr = __va(instr - (u8*)VSYSCALL_START + (u8*)__pa_symbol(&__vsyscall_0));
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DPRINTK("%s: vsyscall fixup: %p => %p\n",
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__func__, a->instr, instr);
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}
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#endif
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memcpy(insnbuf, a->replacement, a->replacementlen);
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if (*insnbuf == 0xe8 && a->replacementlen == 5)
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*(s32 *)(insnbuf + 1) += a->replacement - a->instr;
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add_nops(insnbuf + a->replacementlen,
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a->instrlen - a->replacementlen);
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text_poke_early(instr, insnbuf, a->instrlen);
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}
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}
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#ifdef CONFIG_SMP
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static void alternatives_smp_lock(const s32 *start, const s32 *end,
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u8 *text, u8 *text_end)
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{
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const s32 *poff;
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mutex_lock(&text_mutex);
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for (poff = start; poff < end; poff++) {
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u8 *ptr = (u8 *)poff + *poff;
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if (!*poff || ptr < text || ptr >= text_end)
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continue;
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/* turn DS segment override prefix into lock prefix */
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if (*ptr == 0x3e)
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text_poke(ptr, ((unsigned char []){0xf0}), 1);
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};
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mutex_unlock(&text_mutex);
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}
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static void alternatives_smp_unlock(const s32 *start, const s32 *end,
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u8 *text, u8 *text_end)
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{
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const s32 *poff;
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if (noreplace_smp)
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return;
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mutex_lock(&text_mutex);
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for (poff = start; poff < end; poff++) {
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u8 *ptr = (u8 *)poff + *poff;
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if (!*poff || ptr < text || ptr >= text_end)
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continue;
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/* turn lock prefix into DS segment override prefix */
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if (*ptr == 0xf0)
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text_poke(ptr, ((unsigned char []){0x3E}), 1);
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};
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mutex_unlock(&text_mutex);
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}
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struct smp_alt_module {
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/* what is this ??? */
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struct module *mod;
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char *name;
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/* ptrs to lock prefixes */
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const s32 *locks;
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const s32 *locks_end;
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/* .text segment, needed to avoid patching init code ;) */
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u8 *text;
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u8 *text_end;
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struct list_head next;
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};
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static LIST_HEAD(smp_alt_modules);
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static DEFINE_MUTEX(smp_alt);
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static int smp_mode = 1; /* protected by smp_alt */
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void __init_or_module alternatives_smp_module_add(struct module *mod,
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char *name,
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void *locks, void *locks_end,
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void *text, void *text_end)
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{
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struct smp_alt_module *smp;
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if (noreplace_smp)
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return;
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if (smp_alt_once) {
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if (boot_cpu_has(X86_FEATURE_UP))
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alternatives_smp_unlock(locks, locks_end,
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text, text_end);
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return;
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}
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smp = kzalloc(sizeof(*smp), GFP_KERNEL);
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if (NULL == smp)
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return; /* we'll run the (safe but slow) SMP code then ... */
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smp->mod = mod;
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smp->name = name;
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smp->locks = locks;
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smp->locks_end = locks_end;
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smp->text = text;
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smp->text_end = text_end;
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DPRINTK("%s: locks %p -> %p, text %p -> %p, name %s\n",
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__func__, smp->locks, smp->locks_end,
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smp->text, smp->text_end, smp->name);
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mutex_lock(&smp_alt);
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list_add_tail(&smp->next, &smp_alt_modules);
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if (boot_cpu_has(X86_FEATURE_UP))
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alternatives_smp_unlock(smp->locks, smp->locks_end,
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smp->text, smp->text_end);
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mutex_unlock(&smp_alt);
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}
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void __init_or_module alternatives_smp_module_del(struct module *mod)
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{
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struct smp_alt_module *item;
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if (smp_alt_once || noreplace_smp)
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return;
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mutex_lock(&smp_alt);
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list_for_each_entry(item, &smp_alt_modules, next) {
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if (mod != item->mod)
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continue;
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list_del(&item->next);
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mutex_unlock(&smp_alt);
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DPRINTK("%s: %s\n", __func__, item->name);
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kfree(item);
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return;
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}
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mutex_unlock(&smp_alt);
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}
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bool skip_smp_alternatives;
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void alternatives_smp_switch(int smp)
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{
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struct smp_alt_module *mod;
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#ifdef CONFIG_LOCKDEP
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/*
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* Older binutils section handling bug prevented
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* alternatives-replacement from working reliably.
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*
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* If this still occurs then you should see a hang
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* or crash shortly after this line:
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*/
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printk("lockdep: fixing up alternatives.\n");
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#endif
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if (noreplace_smp || smp_alt_once || skip_smp_alternatives)
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return;
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BUG_ON(!smp && (num_online_cpus() > 1));
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mutex_lock(&smp_alt);
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/*
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* Avoid unnecessary switches because it forces JIT based VMs to
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* throw away all cached translations, which can be quite costly.
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*/
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if (smp == smp_mode) {
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/* nothing */
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} else if (smp) {
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printk(KERN_INFO "SMP alternatives: switching to SMP code\n");
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clear_cpu_cap(&boot_cpu_data, X86_FEATURE_UP);
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clear_cpu_cap(&cpu_data(0), X86_FEATURE_UP);
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list_for_each_entry(mod, &smp_alt_modules, next)
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alternatives_smp_lock(mod->locks, mod->locks_end,
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mod->text, mod->text_end);
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} else {
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printk(KERN_INFO "SMP alternatives: switching to UP code\n");
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set_cpu_cap(&boot_cpu_data, X86_FEATURE_UP);
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set_cpu_cap(&cpu_data(0), X86_FEATURE_UP);
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list_for_each_entry(mod, &smp_alt_modules, next)
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alternatives_smp_unlock(mod->locks, mod->locks_end,
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mod->text, mod->text_end);
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}
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smp_mode = smp;
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mutex_unlock(&smp_alt);
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}
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/* Return 1 if the address range is reserved for smp-alternatives */
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int alternatives_text_reserved(void *start, void *end)
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{
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struct smp_alt_module *mod;
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const s32 *poff;
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u8 *text_start = start;
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u8 *text_end = end;
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list_for_each_entry(mod, &smp_alt_modules, next) {
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if (mod->text > text_end || mod->text_end < text_start)
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continue;
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for (poff = mod->locks; poff < mod->locks_end; poff++) {
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const u8 *ptr = (const u8 *)poff + *poff;
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if (text_start <= ptr && text_end > ptr)
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return 1;
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}
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}
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return 0;
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}
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#endif
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#ifdef CONFIG_PARAVIRT
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void __init_or_module apply_paravirt(struct paravirt_patch_site *start,
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struct paravirt_patch_site *end)
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{
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struct paravirt_patch_site *p;
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char insnbuf[MAX_PATCH_LEN];
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if (noreplace_paravirt)
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return;
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for (p = start; p < end; p++) {
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unsigned int used;
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BUG_ON(p->len > MAX_PATCH_LEN);
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/* prep the buffer with the original instructions */
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memcpy(insnbuf, p->instr, p->len);
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used = pv_init_ops.patch(p->instrtype, p->clobbers, insnbuf,
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(unsigned long)p->instr, p->len);
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BUG_ON(used > p->len);
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/* Pad the rest with nops */
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add_nops(insnbuf + used, p->len - used);
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text_poke_early(p->instr, insnbuf, p->len);
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}
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}
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extern struct paravirt_patch_site __start_parainstructions[],
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__stop_parainstructions[];
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#endif /* CONFIG_PARAVIRT */
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void __init alternative_instructions(void)
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{
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/* The patching is not fully atomic, so try to avoid local interruptions
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that might execute the to be patched code.
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Other CPUs are not running. */
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stop_nmi();
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/*
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* Don't stop machine check exceptions while patching.
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* MCEs only happen when something got corrupted and in this
|
|
* case we must do something about the corruption.
|
|
* Ignoring it is worse than a unlikely patching race.
|
|
* Also machine checks tend to be broadcast and if one CPU
|
|
* goes into machine check the others follow quickly, so we don't
|
|
* expect a machine check to cause undue problems during to code
|
|
* patching.
|
|
*/
|
|
|
|
apply_alternatives(__alt_instructions, __alt_instructions_end);
|
|
|
|
/* switch to patch-once-at-boottime-only mode and free the
|
|
* tables in case we know the number of CPUs will never ever
|
|
* change */
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
if (num_possible_cpus() < 2)
|
|
smp_alt_once = 1;
|
|
#endif
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (smp_alt_once) {
|
|
if (1 == num_possible_cpus()) {
|
|
printk(KERN_INFO "SMP alternatives: switching to UP code\n");
|
|
set_cpu_cap(&boot_cpu_data, X86_FEATURE_UP);
|
|
set_cpu_cap(&cpu_data(0), X86_FEATURE_UP);
|
|
|
|
alternatives_smp_unlock(__smp_locks, __smp_locks_end,
|
|
_text, _etext);
|
|
}
|
|
} else {
|
|
alternatives_smp_module_add(NULL, "core kernel",
|
|
__smp_locks, __smp_locks_end,
|
|
_text, _etext);
|
|
|
|
/* Only switch to UP mode if we don't immediately boot others */
|
|
if (num_present_cpus() == 1 || setup_max_cpus <= 1)
|
|
alternatives_smp_switch(0);
|
|
}
|
|
#endif
|
|
apply_paravirt(__parainstructions, __parainstructions_end);
|
|
|
|
if (smp_alt_once)
|
|
free_init_pages("SMP alternatives",
|
|
(unsigned long)__smp_locks,
|
|
(unsigned long)__smp_locks_end);
|
|
|
|
restart_nmi();
|
|
}
|
|
|
|
/**
|
|
* text_poke_early - Update instructions on a live kernel at boot time
|
|
* @addr: address to modify
|
|
* @opcode: source of the copy
|
|
* @len: length to copy
|
|
*
|
|
* When you use this code to patch more than one byte of an instruction
|
|
* you need to make sure that other CPUs cannot execute this code in parallel.
|
|
* Also no thread must be currently preempted in the middle of these
|
|
* instructions. And on the local CPU you need to be protected again NMI or MCE
|
|
* handlers seeing an inconsistent instruction while you patch.
|
|
*/
|
|
void *__init_or_module text_poke_early(void *addr, const void *opcode,
|
|
size_t len)
|
|
{
|
|
unsigned long flags;
|
|
local_irq_save(flags);
|
|
memcpy(addr, opcode, len);
|
|
sync_core();
|
|
local_irq_restore(flags);
|
|
/* Could also do a CLFLUSH here to speed up CPU recovery; but
|
|
that causes hangs on some VIA CPUs. */
|
|
return addr;
|
|
}
|
|
|
|
/**
|
|
* text_poke - Update instructions on a live kernel
|
|
* @addr: address to modify
|
|
* @opcode: source of the copy
|
|
* @len: length to copy
|
|
*
|
|
* Only atomic text poke/set should be allowed when not doing early patching.
|
|
* It means the size must be writable atomically and the address must be aligned
|
|
* in a way that permits an atomic write. It also makes sure we fit on a single
|
|
* page.
|
|
*
|
|
* Note: Must be called under text_mutex.
|
|
*/
|
|
void *__kprobes text_poke(void *addr, const void *opcode, size_t len)
|
|
{
|
|
unsigned long flags;
|
|
char *vaddr;
|
|
struct page *pages[2];
|
|
int i;
|
|
|
|
if (!core_kernel_text((unsigned long)addr)) {
|
|
pages[0] = vmalloc_to_page(addr);
|
|
pages[1] = vmalloc_to_page(addr + PAGE_SIZE);
|
|
} else {
|
|
pages[0] = virt_to_page(addr);
|
|
WARN_ON(!PageReserved(pages[0]));
|
|
pages[1] = virt_to_page(addr + PAGE_SIZE);
|
|
}
|
|
BUG_ON(!pages[0]);
|
|
local_irq_save(flags);
|
|
set_fixmap(FIX_TEXT_POKE0, page_to_phys(pages[0]));
|
|
if (pages[1])
|
|
set_fixmap(FIX_TEXT_POKE1, page_to_phys(pages[1]));
|
|
vaddr = (char *)fix_to_virt(FIX_TEXT_POKE0);
|
|
memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);
|
|
clear_fixmap(FIX_TEXT_POKE0);
|
|
if (pages[1])
|
|
clear_fixmap(FIX_TEXT_POKE1);
|
|
local_flush_tlb();
|
|
sync_core();
|
|
/* Could also do a CLFLUSH here to speed up CPU recovery; but
|
|
that causes hangs on some VIA CPUs. */
|
|
for (i = 0; i < len; i++)
|
|
BUG_ON(((char *)addr)[i] != ((char *)opcode)[i]);
|
|
local_irq_restore(flags);
|
|
return addr;
|
|
}
|
|
|
|
/*
|
|
* Cross-modifying kernel text with stop_machine().
|
|
* This code originally comes from immediate value.
|
|
*/
|
|
static atomic_t stop_machine_first;
|
|
static int wrote_text;
|
|
|
|
struct text_poke_params {
|
|
struct text_poke_param *params;
|
|
int nparams;
|
|
};
|
|
|
|
static int __kprobes stop_machine_text_poke(void *data)
|
|
{
|
|
struct text_poke_params *tpp = data;
|
|
struct text_poke_param *p;
|
|
int i;
|
|
|
|
if (atomic_dec_and_test(&stop_machine_first)) {
|
|
for (i = 0; i < tpp->nparams; i++) {
|
|
p = &tpp->params[i];
|
|
text_poke(p->addr, p->opcode, p->len);
|
|
}
|
|
smp_wmb(); /* Make sure other cpus see that this has run */
|
|
wrote_text = 1;
|
|
} else {
|
|
while (!wrote_text)
|
|
cpu_relax();
|
|
smp_mb(); /* Load wrote_text before following execution */
|
|
}
|
|
|
|
for (i = 0; i < tpp->nparams; i++) {
|
|
p = &tpp->params[i];
|
|
flush_icache_range((unsigned long)p->addr,
|
|
(unsigned long)p->addr + p->len);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* text_poke_smp - Update instructions on a live kernel on SMP
|
|
* @addr: address to modify
|
|
* @opcode: source of the copy
|
|
* @len: length to copy
|
|
*
|
|
* Modify multi-byte instruction by using stop_machine() on SMP. This allows
|
|
* user to poke/set multi-byte text on SMP. Only non-NMI/MCE code modifying
|
|
* should be allowed, since stop_machine() does _not_ protect code against
|
|
* NMI and MCE.
|
|
*
|
|
* Note: Must be called under get_online_cpus() and text_mutex.
|
|
*/
|
|
void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len)
|
|
{
|
|
struct text_poke_params tpp;
|
|
struct text_poke_param p;
|
|
|
|
p.addr = addr;
|
|
p.opcode = opcode;
|
|
p.len = len;
|
|
tpp.params = &p;
|
|
tpp.nparams = 1;
|
|
atomic_set(&stop_machine_first, 1);
|
|
wrote_text = 0;
|
|
/* Use __stop_machine() because the caller already got online_cpus. */
|
|
__stop_machine(stop_machine_text_poke, (void *)&tpp, cpu_online_mask);
|
|
return addr;
|
|
}
|
|
|
|
/**
|
|
* text_poke_smp_batch - Update instructions on a live kernel on SMP
|
|
* @params: an array of text_poke parameters
|
|
* @n: the number of elements in params.
|
|
*
|
|
* Modify multi-byte instruction by using stop_machine() on SMP. Since the
|
|
* stop_machine() is heavy task, it is better to aggregate text_poke requests
|
|
* and do it once if possible.
|
|
*
|
|
* Note: Must be called under get_online_cpus() and text_mutex.
|
|
*/
|
|
void __kprobes text_poke_smp_batch(struct text_poke_param *params, int n)
|
|
{
|
|
struct text_poke_params tpp = {.params = params, .nparams = n};
|
|
|
|
atomic_set(&stop_machine_first, 1);
|
|
wrote_text = 0;
|
|
stop_machine(stop_machine_text_poke, (void *)&tpp, NULL);
|
|
}
|
|
|
|
#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
|
|
|
|
#ifdef CONFIG_X86_64
|
|
unsigned char ideal_nop5[5] = { 0x66, 0x66, 0x66, 0x66, 0x90 };
|
|
#else
|
|
unsigned char ideal_nop5[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
|
|
#endif
|
|
|
|
void __init arch_init_ideal_nop5(void)
|
|
{
|
|
/*
|
|
* There is no good nop for all x86 archs. This selection
|
|
* algorithm should be unified with the one in find_nop_table(),
|
|
* but this should be good enough for now.
|
|
*
|
|
* For cases other than the ones below, use the safe (as in
|
|
* always functional) defaults above.
|
|
*/
|
|
#ifdef CONFIG_X86_64
|
|
/* Don't use these on 32 bits due to broken virtualizers */
|
|
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
|
|
memcpy(ideal_nop5, p6_nops[5], 5);
|
|
#endif
|
|
}
|
|
#endif
|