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From: David Woodhouse <dwmw@amazon.co.uk>
To: Andi Kleen <ak@linux.intel.com>
Cc: Paul Turner <pjt@google.com>, LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linux-foundation.org>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	tglx@linutronix.de, Kees Cook <keescook@google.com>,
	Rik van Riel <riel@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@amacapital.net>,
	Jiri Kosina <jikos@kernel.org>,
	gnomes@lxorguk.ukuu.org.uk, x86@kernel.org,
	thomas.lendacky@amd.com, Josh Poimboeuf <jpoimboe@redhat.com>
Subject: [PATCH v8 03/12] x86/retpoline: Add initial retpoline support
Date: Thu, 11 Jan 2018 21:46:25 +0000
Message-ID: <1515707194-20531-4-git-send-email-dwmw@amazon.co.uk> (raw)
In-Reply-To: <1515707194-20531-1-git-send-email-dwmw@amazon.co.uk>

Enable the use of -mindirect-branch=thunk-extern in newer GCC, and provide
the corresponding thunks. Provide assembler macros for invoking the thunks
in the same way that GCC does, from native and inline assembler.

This adds X86_FEATURE_RETPOLINE and sets it by default on all CPUs. In
some circumstances, IBRS microcode features may be used instead, and the
retpoline can be disabled.

On AMD CPUs if lfence is serialising, the retpoline can be dramatically
simplified to a simple "lfence; jmp *\reg". A future patch, after it has
been verified that lfence really is serialising in all circumstances, can
enable this by setting the X86_FEATURE_RETPOLINE_AMD feature bit in addition
to X86_FEATURE_RETPOLINE.

Do not align the retpoline in the altinstr section, because there is no
guarantee that it stays aligned when it's copied over the oldinstr during
alternative patching.

[ Andi Kleen: Rename the macros, add CONFIG_RETPOLINE option, export thunks]
[ tglx: Put actual function CALL/JMP in front of the macros, convert to
  	symbolic labels ]
[ dwmw2: Convert back to numeric labels, merge objtool fixes ]

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: https://lkml.kernel.org/r/1515508997-6154-2-git-send-email-dwmw@amazon.co.uk
---
 arch/x86/Kconfig                      |  13 ++++
 arch/x86/Makefile                     |  10 +++
 arch/x86/include/asm/asm-prototypes.h |  25 +++++++
 arch/x86/include/asm/cpufeatures.h    |   2 +
 arch/x86/include/asm/nospec-branch.h  | 128 ++++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/common.c          |   4 ++
 arch/x86/lib/Makefile                 |   1 +
 arch/x86/lib/retpoline.S              |  48 +++++++++++++
 8 files changed, 231 insertions(+)
 create mode 100644 arch/x86/include/asm/nospec-branch.h
 create mode 100644 arch/x86/lib/retpoline.S

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e23d21a..d181916 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -429,6 +429,19 @@ config GOLDFISH
        def_bool y
        depends on X86_GOLDFISH
 
+config RETPOLINE
+	bool "Avoid speculative indirect branches in kernel"
+	default y
+	help
+	  Compile kernel with the retpoline compiler options to guard against
+	  kernel-to-user data leaks by avoiding speculative indirect
+	  branches. Requires a compiler with -mindirect-branch=thunk-extern
+	  support for full protection. The kernel may run slower.
+
+	  Without compiler support, at least indirect branches in assembler
+	  code are eliminated. Since this includes the syscall entry path,
+	  it is not entirely pointless.
+
 config INTEL_RDT
 	bool "Intel Resource Director Technology support"
 	default n
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index a20eacd..974c618 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -235,6 +235,16 @@ KBUILD_CFLAGS += -Wno-sign-compare
 #
 KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
 
+# Avoid indirect branches in kernel to deal with Spectre
+ifdef CONFIG_RETPOLINE
+    RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)
+    ifneq ($(RETPOLINE_CFLAGS),)
+        KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) -DRETPOLINE
+    else
+        $(warning CONFIG_RETPOLINE=y, but not supported by the compiler. Toolchain update recommended.)
+    endif
+endif
+
 archscripts: scripts_basic
 	$(Q)$(MAKE) $(build)=arch/x86/tools relocs
 
diff --git a/arch/x86/include/asm/asm-prototypes.h b/arch/x86/include/asm/asm-prototypes.h
index ff700d8..0927cdc 100644
--- a/arch/x86/include/asm/asm-prototypes.h
+++ b/arch/x86/include/asm/asm-prototypes.h
@@ -11,7 +11,32 @@
 #include <asm/pgtable.h>
 #include <asm/special_insns.h>
 #include <asm/preempt.h>
+#include <asm/asm.h>
 
 #ifndef CONFIG_X86_CMPXCHG64
 extern void cmpxchg8b_emu(void);
 #endif
+
+#ifdef CONFIG_RETPOLINE
+#ifdef CONFIG_X86_32
+#define INDIRECT_THUNK(reg) extern asmlinkage void __x86_indirect_thunk_e ## reg(void);
+#else
+#define INDIRECT_THUNK(reg) extern asmlinkage void __x86_indirect_thunk_r ## reg(void);
+INDIRECT_THUNK(8)
+INDIRECT_THUNK(9)
+INDIRECT_THUNK(10)
+INDIRECT_THUNK(11)
+INDIRECT_THUNK(12)
+INDIRECT_THUNK(13)
+INDIRECT_THUNK(14)
+INDIRECT_THUNK(15)
+#endif
+INDIRECT_THUNK(ax)
+INDIRECT_THUNK(bx)
+INDIRECT_THUNK(cx)
+INDIRECT_THUNK(dx)
+INDIRECT_THUNK(si)
+INDIRECT_THUNK(di)
+INDIRECT_THUNK(bp)
+INDIRECT_THUNK(sp)
+#endif /* CONFIG_RETPOLINE */
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 1641c2f..f275447 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -203,6 +203,8 @@
 #define X86_FEATURE_PROC_FEEDBACK	( 7*32+ 9) /* AMD ProcFeedbackInterface */
 #define X86_FEATURE_SME			( 7*32+10) /* AMD Secure Memory Encryption */
 #define X86_FEATURE_PTI			( 7*32+11) /* Kernel Page Table Isolation enabled */
+#define X86_FEATURE_RETPOLINE		( 7*32+12) /* Generic Retpoline mitigation for Spectre variant 2 */
+#define X86_FEATURE_RETPOLINE_AMD	( 7*32+13) /* AMD Retpoline mitigation for Spectre variant 2 */
 #define X86_FEATURE_INTEL_PPIN		( 7*32+14) /* Intel Processor Inventory Number */
 #define X86_FEATURE_INTEL_PT		( 7*32+15) /* Intel Processor Trace */
 #define X86_FEATURE_AVX512_4VNNIW	( 7*32+16) /* AVX-512 Neural Network Instructions */
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
new file mode 100644
index 0000000..e20e92e
--- /dev/null
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __NOSPEC_BRANCH_H__
+#define __NOSPEC_BRANCH_H__
+
+#include <asm/alternative.h>
+#include <asm/alternative-asm.h>
+#include <asm/cpufeatures.h>
+
+#ifdef __ASSEMBLY__
+
+/*
+ * This should be used immediately before a retpoline alternative.  It tells
+ * objtool where the retpolines are so that it can make sense of the control
+ * flow by just reading the original instruction(s) and ignoring the
+ * alternatives.
+ */
+.macro ANNOTATE_NOSPEC_ALTERNATIVE
+	.Lannotate_\@:
+	.pushsection .discard.nospec
+	.long .Lannotate_\@ - .
+	.popsection
+.endm
+
+/*
+ * These are the bare retpoline primitives for indirect jmp and call.
+ * Do not use these directly; they only exist to make the ALTERNATIVE
+ * invocation below less ugly.
+ */
+.macro RETPOLINE_JMP reg:req
+	call	.Ldo_rop_\@
+.Lspec_trap_\@:
+	pause
+	jmp	.Lspec_trap_\@
+.Ldo_rop_\@:
+	mov	\reg, (%_ASM_SP)
+	ret
+.endm
+
+/*
+ * This is a wrapper around RETPOLINE_JMP so the called function in reg
+ * returns to the instruction after the macro.
+ */
+.macro RETPOLINE_CALL reg:req
+	jmp	.Ldo_call_\@
+.Ldo_retpoline_jmp_\@:
+	RETPOLINE_JMP \reg
+.Ldo_call_\@:
+	call	.Ldo_retpoline_jmp_\@
+.endm
+
+/*
+ * JMP_NOSPEC and CALL_NOSPEC macros can be used instead of a simple
+ * indirect jmp/call which may be susceptible to the Spectre variant 2
+ * attack.
+ */
+.macro JMP_NOSPEC reg:req
+#ifdef CONFIG_RETPOLINE
+	ANNOTATE_NOSPEC_ALTERNATIVE
+	ALTERNATIVE_2 __stringify(jmp *\reg),				\
+		__stringify(RETPOLINE_JMP \reg), X86_FEATURE_RETPOLINE,	\
+		__stringify(lfence; jmp *\reg), X86_FEATURE_RETPOLINE_AMD
+#else
+	jmp	*\reg
+#endif
+.endm
+
+.macro CALL_NOSPEC reg:req
+#ifdef CONFIG_RETPOLINE
+	ANNOTATE_NOSPEC_ALTERNATIVE
+	ALTERNATIVE_2 __stringify(call *\reg),				\
+		__stringify(RETPOLINE_CALL \reg), X86_FEATURE_RETPOLINE,\
+		__stringify(lfence; call *\reg), X86_FEATURE_RETPOLINE_AMD
+#else
+	call	*\reg
+#endif
+.endm
+
+#else /* __ASSEMBLY__ */
+
+#define ANNOTATE_NOSPEC_ALTERNATIVE				\
+	"999:\n\t"						\
+	".pushsection .discard.nospec\n\t"			\
+	".long 999b - .\n\t"					\
+	".popsection\n\t"
+
+#if defined(CONFIG_X86_64) && defined(RETPOLINE)
+
+/*
+ * Since the inline asm uses the %V modifier which is only in newer GCC,
+ * the 64-bit one is dependent on RETPOLINE not CONFIG_RETPOLINE.
+ */
+# define CALL_NOSPEC						\
+	ANNOTATE_NOSPEC_ALTERNATIVE				\
+	ALTERNATIVE(						\
+	"call *%[thunk_target]\n",				\
+	"call __x86_indirect_thunk_%V[thunk_target]\n",		\
+	X86_FEATURE_RETPOLINE)
+# define THUNK_TARGET(addr) [thunk_target] "r" (addr)
+
+#elif defined(CONFIG_X86_32) && defined(CONFIG_RETPOLINE)
+/*
+ * For i386 we use the original ret-equivalent retpoline, because
+ * otherwise we'll run out of registers. We don't care about CET
+ * here, anyway.
+ */
+# define CALL_NOSPEC ALTERNATIVE("call *%[thunk_target]\n",	\
+	"       jmp    904f;\n"					\
+	"       .align 16\n"					\
+	"901:	call   903f;\n"					\
+	"902:	pause;\n"					\
+	"       jmp    902b;\n"					\
+	"       .align 16\n"					\
+	"903:	addl   $4, %%esp;\n"				\
+	"       pushl  %[thunk_target];\n"			\
+	"       ret;\n"						\
+	"       .align 16\n"					\
+	"904:	call   901b;\n",				\
+	X86_FEATURE_RETPOLINE)
+
+# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
+#else /* No retpoline */
+# define CALL_NOSPEC "call *%[thunk_target]\n"
+# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
+#endif
+
+#endif /* __ASSEMBLY__ */
+#endif /* __NOSPEC_BRANCH_H__ */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 372ba3f..7a671d1 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -905,6 +905,10 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 	setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
 	setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
 
+#ifdef CONFIG_RETPOLINE
+	setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
+#endif
+
 	fpu__init_system(c);
 
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 457f681..d435c89 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -26,6 +26,7 @@ lib-y += memcpy_$(BITS).o
 lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
 lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
+lib-$(CONFIG_RETPOLINE) += retpoline.o
 
 obj-y += msr.o msr-reg.o msr-reg-export.o hweight.o
 
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
new file mode 100644
index 0000000..cb45c6c
--- /dev/null
+++ b/arch/x86/lib/retpoline.S
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/stringify.h>
+#include <linux/linkage.h>
+#include <asm/dwarf2.h>
+#include <asm/cpufeatures.h>
+#include <asm/alternative-asm.h>
+#include <asm/export.h>
+#include <asm/nospec-branch.h>
+
+.macro THUNK reg
+	.section .text.__x86.indirect_thunk.\reg
+
+ENTRY(__x86_indirect_thunk_\reg)
+	CFI_STARTPROC
+	JMP_NOSPEC %\reg
+	CFI_ENDPROC
+ENDPROC(__x86_indirect_thunk_\reg)
+.endm
+
+/*
+ * Despite being an assembler file we can't just use .irp here
+ * because __KSYM_DEPS__ only uses the C preprocessor and would
+ * only see one instance of "__x86_indirect_thunk_\reg" rather
+ * than one per register with the correct names. So we do it
+ * the simple and nasty way...
+ */
+#define EXPORT_THUNK(reg) EXPORT_SYMBOL(__x86_indirect_thunk_ ## reg)
+#define GENERATE_THUNK(reg) THUNK reg ; EXPORT_THUNK(reg)
+
+GENERATE_THUNK(_ASM_AX)
+GENERATE_THUNK(_ASM_BX)
+GENERATE_THUNK(_ASM_CX)
+GENERATE_THUNK(_ASM_DX)
+GENERATE_THUNK(_ASM_SI)
+GENERATE_THUNK(_ASM_DI)
+GENERATE_THUNK(_ASM_BP)
+GENERATE_THUNK(_ASM_SP)
+#ifdef CONFIG_64BIT
+GENERATE_THUNK(r8)
+GENERATE_THUNK(r9)
+GENERATE_THUNK(r10)
+GENERATE_THUNK(r11)
+GENERATE_THUNK(r12)
+GENERATE_THUNK(r13)
+GENERATE_THUNK(r14)
+GENERATE_THUNK(r15)
+#endif
-- 
2.7.4

  parent reply index

Thread overview: 85+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-11 21:46 [PATCH v8 00/12] Retpoline: Avoid speculative indirect calls in kernel David Woodhouse
2018-01-11 21:46 ` [PATCH v8 01/12] objtool: Detect jumps to retpoline thunks David Woodhouse
2018-01-11 23:22   ` [tip:x86/pti] " tip-bot for Josh Poimboeuf
2018-01-11 21:46 ` [PATCH v8 02/12] objtool: Allow alternatives to be ignored David Woodhouse
2018-01-11 23:22   ` [tip:x86/pti] " tip-bot for Josh Poimboeuf
2018-01-18 19:09   ` [v8,02/12] " Guenter Roeck
2018-01-18 19:33     ` Josh Poimboeuf
2018-01-18 19:41       ` Guenter Roeck
2018-01-22 19:34         ` David Woodhouse
2018-01-22 20:25           ` Guenter Roeck
2018-01-22 20:27             ` David Woodhouse
2018-01-28 21:06             ` Josh Poimboeuf
2018-01-29  1:26               ` Guenter Roeck
2018-01-29 17:15               ` Guenter Roeck
2018-01-29 17:30                 ` Josh Poimboeuf
2018-01-22 19:27       ` Guenter Roeck
2018-01-11 21:46 ` David Woodhouse [this message]
2018-01-11 23:23   ` [tip:x86/pti] x86/retpoline: Add initial retpoline support tip-bot for David Woodhouse
2018-01-11 23:58   ` [PATCH v8 03/12] " Tom Lendacky
2018-01-12 10:28     ` David Woodhouse
2018-01-12 14:02       ` Tom Lendacky
2018-01-14 15:02   ` Borislav Petkov
2018-01-14 15:53     ` Josh Poimboeuf
2018-01-14 15:59       ` Borislav Petkov
2018-01-11 21:46 ` [PATCH v8 04/12] x86/spectre: Add boot time option to select Spectre v2 mitigation David Woodhouse
2018-01-11 23:23   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-23 22:40   ` [PATCH v8 04/12] " Borislav Petkov
2018-01-23 22:53     ` David Woodhouse
2018-01-23 23:05       ` Andi Kleen
2018-01-23 22:55     ` Jiri Kosina
2018-01-23 23:05       ` Borislav Petkov
2018-01-24  0:32         ` Kees Cook
2018-01-24  9:58           ` Borislav Petkov
2018-01-23 23:06       ` Jiri Kosina
2018-01-23 23:21       ` Andi Kleen
2018-01-23 23:24         ` Jiri Kosina
2018-01-23 23:45           ` Andi Kleen
2018-01-23 23:49             ` Jiri Kosina
2018-01-24  4:26               ` Greg Kroah-Hartman
2018-01-24  9:56                 ` Jiri Kosina
2018-01-24 13:58                   ` Greg Kroah-Hartman
2018-01-24 14:03                     ` Jiri Kosina
2018-01-24 14:22                       ` Greg Kroah-Hartman
2018-01-11 21:46 ` [PATCH v8 05/12] x86/retpoline/crypto: Convert crypto assembler indirect jumps David Woodhouse
2018-01-11 23:24   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 06/12] x86/retpoline/entry: Convert entry " David Woodhouse
2018-01-11 23:24   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 07/12] x86/retpoline/ftrace: Convert ftrace " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 08/12] x86/retpoline/hyperv: Convert " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 09/12] x86/retpoline/xen: Convert Xen hypercall " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 10/12] x86/retpoline/checksum32: Convert assembler " David Woodhouse
2018-01-11 23:26   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 11/12] x86/retpoline/irq32: " David Woodhouse
2018-01-11 23:26   ` [tip:x86/pti] " tip-bot for Andi Kleen
2018-01-11 21:46 ` [PATCH v8 12/12] x86/retpoline: Fill return stack buffer on vmexit David Woodhouse
2018-01-11 23:27   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 23:51   ` [PATCH v8 12/12] " Andi Kleen
2018-01-12 11:11     ` [PATCH v8.1 " David Woodhouse
2018-01-12 11:15       ` Thomas Gleixner
2018-01-12 11:21         ` Woodhouse, David
2018-01-12 11:37       ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-14 14:50         ` Borislav Petkov
2018-01-14 15:28           ` Thomas Gleixner
2018-01-14 15:35         ` Borislav Petkov
2018-01-25 12:07         ` Borislav Petkov
2018-01-25 12:20           ` David Woodhouse
2018-01-25 12:45             ` Borislav Petkov
2018-01-25 15:10               ` Josh Poimboeuf
2018-01-25 15:51                 ` Borislav Petkov
2018-01-25 16:03                   ` David Woodhouse
2018-01-25 16:56                     ` Josh Poimboeuf
2018-01-25 17:00                       ` David Woodhouse
2018-01-25 17:05                         ` Andy Lutomirski
2018-01-25 17:44                           ` Josh Poimboeuf
2018-01-25 18:41                           ` Jiri Kosina
2018-01-25 17:10                         ` Thomas Gleixner
2018-01-25 17:32                         ` Josh Poimboeuf
2018-01-25 17:53                         ` Borislav Petkov
2018-01-25 18:04                           ` David Woodhouse
2018-01-25 18:32                             ` Josh Poimboeuf
2018-01-25 19:07                             ` Borislav Petkov
2018-01-25 19:10                               ` Borislav Petkov

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	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git