From 1a63cf5cb98b6bbd6a51b4b97b19c3c34c59bd8c Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Thu, 11 Jan 2018 21:46:28 +0000 Subject: [PATCH] x86/retpoline/entry: Convert entry assembler indirect jumps commit 2641f08bb7fc63a636a2b18173221d7040a3512e upstream. Convert indirect jumps in core 32/64bit entry assembler code to use non-speculative sequences when CONFIG_RETPOLINE is enabled. Don't use CALL_NOSPEC in entry_SYSCALL_64_fastpath because the return address after the 'call' instruction must be *precisely* at the .Lentry_SYSCALL_64_after_fastpath label for stub_ptregs_64 to work, and the use of alternatives will mess that up unless we play horrid games to prepend with NOPs and make the variants the same length. It's not worth it; in the case where we ALTERNATIVE out the retpoline, the first instruction at __x86.indirect_thunk.rax is going to be a bare jmp *%rax anyway. Signed-off-by: David Woodhouse Signed-off-by: Thomas Gleixner Acked-by: Ingo Molnar Acked-by: Arjan van de Ven Cc: gnomes@lxorguk.ukuu.org.uk Cc: Rik van Riel Cc: Andi Kleen Cc: Josh Poimboeuf Cc: thomas.lendacky@amd.com Cc: Peter Zijlstra Cc: Linus Torvalds Cc: Jiri Kosina Cc: Andy Lutomirski Cc: Dave Hansen Cc: Kees Cook Cc: Tim Chen Cc: Greg Kroah-Hartman Cc: Paul Turner Link: https://lkml.kernel.org/r/1515707194-20531-7-git-send-email-dwmw@amazon.co.uk Signed-off-by: David Woodhouse Signed-off-by: Razvan Ghitulete [bwh: Backported to 3.2: - Also update indirect jumps through system call table in entry_32.s and ia32entry.S - Adjust filenames, context] Signed-off-by: Ben Hutchings --- Reading git-format-patch failed