Messages in this thread Patch in this message | | | Date | Tue, 30 Jan 2018 22:13:33 -0600 | From | Josh Poimboeuf <> | Subject | [PATCH] x86/paravirt: Remove 'noreplace-paravirt' cmdline option |
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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> --- Documentation/admin-guide/kernel-parameters.txt | 2 -- arch/x86/kernel/alternative.c | 14 -------------- 2 files changed, 16 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a205567f537f..f6741a5d89e7 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2739,8 +2739,6 @@ 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 diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 30571fdaaf6f..a481763a3776 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -46,17 +46,6 @@ static int __init setup_noreplace_smp(char *str) } __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) \ @@ -599,9 +588,6 @@ void __init_or_module apply_paravirt(struct paravirt_patch_site *start, struct paravirt_patch_site *p; char insnbuf[MAX_PATCH_LEN]; - if (noreplace_paravirt) - return; - for (p = start; p < end; p++) { unsigned int used; -- 2.14.3
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