4.4-stable review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu mhiramat@kernel.org
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 mhiramat@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Acked-by: David Woodhouse dwmw@amazon.co.uk Cc: Andi Kleen ak@linux.intel.com Cc: Peter Zijlstra peterz@infradead.org Cc: Ananth N Mavinakayanahalli ananth@linux.vnet.ibm.com Cc: Arjan van de Ven arjan@linux.intel.com Cc: Greg Kroah-Hartman gregkh@linux-foundation.org Link: https://lkml.kernel.org/r/151629206178.10241.6828804696410044771.stgit@devbo... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/include/asm/nospec-branch.h | 3 +++ arch/x86/kernel/vmlinux.lds.S | 7 +++++++ arch/x86/lib/retpoline.S | 2 +- 3 files changed, 11 insertions(+), 1 deletion(-)
--- 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 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -104,6 +104,13 @@ 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 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -9,7 +9,7 @@ #include <asm/nospec-branch.h>
.macro THUNK reg - .section .text.__x86.indirect_thunk.\reg + .section .text.__x86.indirect_thunk
ENTRY(__x86_indirect_thunk_\reg) CFI_STARTPROC