4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Josh Poimboeuf jpoimboe@redhat.com
(cherry picked from commit 12c69f1e94c89d40696e83804dd2f0965b5250cd)
The 'noreplace-paravirt' option disables paravirt patching, leaving the original pv indirect calls in place.
That's highly incompatible with retpolines, unless we want to uglify paravirt even further and convert the paravirt calls to retpolines.
As far as I can tell, the option doesn't seem to be useful for much other than introducing surprising corner cases and making the kernel vulnerable to Spectre v2. It was probably a debug option from the early paravirt days. So just remove it.
Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Juergen Gross jgross@suse.com Cc: Andrea Arcangeli aarcange@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Andi Kleen ak@linux.intel.com Cc: Ashok Raj ashok.raj@intel.com Cc: Greg KH gregkh@linuxfoundation.org Cc: Jun Nakajima jun.nakajima@intel.com Cc: Tim Chen tim.c.chen@linux.intel.com Cc: Rusty Russell rusty@rustcorp.com.au Cc: Dave Hansen dave.hansen@intel.com Cc: Asit Mallick asit.k.mallick@intel.com Cc: Andy Lutomirski luto@kernel.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Jason Baron jbaron@akamai.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Alok Kataria akataria@vmware.com Cc: Arjan Van De Ven arjan.van.de.ven@intel.com Cc: David Woodhouse dwmw2@infradead.org Cc: Dan Williams dan.j.williams@intel.com Link: https://lkml.kernel.org/r/20180131041333.2x6blhxirc2kclrq@treble Signed-off-by: David Woodhouse dwmw@amazon.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/kernel-parameters.txt | 2 -- arch/x86/kernel/alternative.c | 14 -------------- 2 files changed, 16 deletions(-)
--- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2805,8 +2805,6 @@ bytes respectively. Such letter suffixes norandmaps Don't use address space randomization. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
- noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops - noreplace-smp [X86-32,SMP] Don't replace SMP instructions with UP alternatives
--- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -46,17 +46,6 @@ static int __init setup_noreplace_smp(ch } __setup("noreplace-smp", setup_noreplace_smp);
-#ifdef CONFIG_PARAVIRT -static int __initdata_or_module noreplace_paravirt = 0; - -static int __init setup_noreplace_paravirt(char *str) -{ - noreplace_paravirt = 1; - return 1; -} -__setup("noreplace-paravirt", setup_noreplace_paravirt); -#endif - #define DPRINTK(fmt, args...) \ do { \ if (debug_alternative) \ @@ -588,9 +577,6 @@ void __init_or_module apply_paravirt(str struct paravirt_patch_site *p; char insnbuf[MAX_PATCH_LEN];
- if (noreplace_paravirt) - return; - for (p = start; p < end; p++) { unsigned int used;