From dc3ba7618f6010e680d1f59a8d18f3063dc404fa Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Fri, 19 Jan 2018 01:14:21 +0900 Subject: [PATCH] retpoline: Introduce start/end markers of indirect thunk commit 736e80a4213e9bbce40a7c050337047128b472ac upstream. Introduce start/end markers of __x86_indirect_thunk_* functions. To make it easy, consolidate .text.__x86.indirect_thunk.* sections to one .text.__x86.indirect_thunk section and put it in the end of kernel text section and adds __indirect_thunk_start/end so that other subsystem (e.g. kprobes) can identify it. Signed-off-by: Masami Hiramatsu Signed-off-by: Thomas Gleixner Acked-by: David Woodhouse Cc: Andi Kleen Cc: Peter Zijlstra Cc: Ananth N Mavinakayanahalli Cc: Arjan van de Ven Cc: Greg Kroah-Hartman Link: https://lkml.kernel.org/r/151629206178.10241.6828804696410044771.stgit@devbox [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- arch/x86/include/asm/nospec-branch.h | 3 +++ arch/x86/kernel/vmlinux.lds.S | 6 ++++++ arch/x86/lib/retpoline.S | 2 +- 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index e28a9ff1246cb..4f7a5d3fed911 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -171,6 +171,9 @@ enum spectre_v2_mitigation { SPECTRE_V2_IBRS, }; +extern char __indirect_thunk_start[]; +extern char __indirect_thunk_end[]; + /* * On VMEXIT we must ensure that no RSB predictions learned in the guest * can be followed in the host, by overwriting the RSB completely. Both diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 0f703f10901a9..35ba1a414f394 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -108,6 +108,12 @@ SECTIONS IRQENTRY_TEXT *(.fixup) *(.gnu.warning) +#ifdef CONFIG_RETPOLINE + __indirect_thunk_start = .; + *(.text.__x86.indirect_thunk) + __indirect_thunk_end = .; +#endif + /* End of text section */ _etext = .; } :text = 0x9090 diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index f849d4733aadb..5e606465e504f 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -8,7 +8,7 @@ #include .macro THUNK reg - .section .text.__x86.indirect_thunk.\reg + .section .text.__x86.indirect_thunk ENTRY(__x86_indirect_thunk_\reg) CFI_STARTPROC -- 2.47.2