From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755261Ab0CVQkc (ORCPT ); Mon, 22 Mar 2010 12:40:32 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:46808 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755135Ab0CVQka (ORCPT ); Mon, 22 Mar 2010 12:40:30 -0400 X-Authority-Analysis: v=1.0 c=1 a=4P3Or4WxehMA:10 a=7U3hwN5JcxgA:10 a=Q9fys5e9bTEA:10 a=20KFwNOVAAAA:8 a=kkjFU2hLSijgi632kNAA:9 a=0KzYDXnp30hg_wQCjP0A:7 a=QX0wBNBElSFgdSaSbjPVXQ1psSUA:4 a=PUjeQqilurYA:10 a=jEp0ucaQiEUA:10 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.89.75 Subject: Re: [PATCH 3/5] jump label: x86 support From: Steven Rostedt Reply-To: rostedt@goodmis.org To: Jason Baron Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, mathieu.desnoyers@polymtl.ca, hpa@zytor.com, tglx@linutronix.de, andi@firstfloor.org, roland@redhat.com, rth@redhat.com, mhiramat@redhat.com, fweisbec@gmail.com In-Reply-To: <5492858ead53ab5c67d11acc620001abe8d36bcb.1269272444.git.jbaron@redhat.com> References: <5492858ead53ab5c67d11acc620001abe8d36bcb.1269272444.git.jbaron@redhat.com> Content-Type: text/plain; charset="ISO-8859-15" Organization: Kihon Technologies Inc. Date: Mon, 22 Mar 2010 12:40:25 -0400 Message-ID: <1269276025.2957.5.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2010-03-22 at 12:07 -0400, Jason Baron wrote: > add x86 support for jump label. I'm keeping this patch separate so its clear to > arch maintainers what was required for x86 support this new feature. hopefully, > it wouldn't be too painful for other arches. > > Signed-off-by: Jason Baron > +#ifdef __HAVE_ARCH_JUMP_LABEL > + > +# ifdef CONFIG_X86_64 > +# define JUMP_LABEL_NOP P6_NOP5 > +# else > +# define JUMP_LABEL_NOP ".byte 0xe9 \n\t .long 0\n\t" > +# endif Are you sure P6_NOP5 can't happen on non 64bit? Just because it is not configured does not mean that the CPU can not handle it. Look at the code I did in arch/x86/kernel/ftrace.c to determine what nop to use. Maybe we can make that generic and have at boot up, the kernel determine a proper 5byte nop. > + > +# define JUMP_LABEL(tag, label, cond) \ > + do { \ > + extern const char __jlstrtab_##tag[]; \ > + asm goto("1:" \ > + JUMP_LABEL_NOP \ > + ".pushsection __jump_table, \"a\" \n\t"\ > + _ASM_PTR "1b, %l[" #label "], %c0 \n\t" \ > + ".popsection \n\t" \ > + : : "i" (__jlstrtab_##tag) : : label);\ > + } while (0) > + > +# endif > + > +#endif > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile > index 4c58352..7cd3bf4 100644 > --- a/arch/x86/kernel/Makefile > +++ b/arch/x86/kernel/Makefile > @@ -32,7 +32,7 @@ GCOV_PROFILE_paravirt.o := n > obj-y := process_$(BITS).o signal.o entry_$(BITS).o > obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o > obj-y += time.o ioport.o ldt.o dumpstack.o > -obj-y += setup.o x86_init.o i8259.o irqinit.o > +obj-y += setup.o x86_init.o i8259.o irqinit.o jump_label.o > obj-$(CONFIG_X86_VISWS) += visws_quirks.o > obj-$(CONFIG_X86_32) += probe_roms_32.o > obj-$(CONFIG_X86_32) += sys_i386_32.o i386_ksyms_32.o > diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c > new file mode 100644 > index 0000000..7fc4f84 > --- /dev/null > +++ b/arch/x86/kernel/jump_label.c > @@ -0,0 +1,53 @@ > +/* > + * jump label x86 support > + * > + * Copyright (C) 2009 Jason Baron > + * > + */ > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#ifdef __HAVE_ARCH_JUMP_LABEL > + > +union jump_code_union { > + char code[RELATIVEJUMP_SIZE]; > + struct { > + char jump; > + int offset; > + } __attribute__((packed)); > +}; > + > +void arch_jump_label_transform(struct jump_entry *entry, enum jump_label_type type) > +{ > + union jump_code_union code; > + > + if (type == JUMP_LABEL_ENABLE) { > + code.jump = 0xe9; > + code.offset = entry->target - (entry->code + RELATIVEJUMP_SIZE); > + } else { > +#ifdef CONFIG_X86_64 > + /* opcode for P6_NOP5 */ > + code.code[0] = 0x0f; > + code.code[1] = 0x1f; > + code.code[2] = 0x44; > + code.code[3] = 0x00; > + code.code[4] = 0x00; > +#else > + code.jump = 0xe9; > + code.offset = 0; > +#endif Same here, and this should also just use the JUMP_LABEL_NOP insead of spelling it out as it does here. memcpy should work. -- Steve > + } > + get_online_cpus(); > + mutex_lock(&text_mutex); > + text_poke_smp((void *)entry->code, &code, RELATIVEJUMP_SIZE); > + mutex_unlock(&text_mutex); > + put_online_cpus(); > +} > + > +#endif