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x86/pti: Add the pti= cmdline option and documentation

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Keep the "nopti" optional for traditional reasons.

[ tglx: Don't allow force on when running on XEN PV and made 'on'
	printout conditional ]

Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171212133952.10177-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Borislav Petkov
2017-12-12 14:39:52 +01:00
committed by Ingo Molnar
parent aa8c6248f8
commit 41f4c20b57
2 changed files with 31 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
arch/x86/mm/pti.c
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@@ -54,21 +54,45 @@ static void __init pti_print_if_insecure(const char *reason)
pr_info("%s\n", reason);
}
static void __init pti_print_if_secure(const char *reason)
{
if (!boot_cpu_has_bug(X86_BUG_CPU_INSECURE))
pr_info("%s\n", reason);
}
void __init pti_check_boottime_disable(void)
{
char arg[5];
int ret;
if (hypervisor_is_type(X86_HYPER_XEN_PV)) {
pti_print_if_insecure("disabled on XEN PV.");
return;
}
ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg));
if (ret > 0) {
if (ret == 3 && !strncmp(arg, "off", 3)) {
pti_print_if_insecure("disabled on command line.");
return;
}
if (ret == 2 && !strncmp(arg, "on", 2)) {
pti_print_if_secure("force enabled on command line.");
goto enable;
}
if (ret == 4 && !strncmp(arg, "auto", 4))
goto autosel;
}
if (cmdline_find_option_bool(boot_command_line, "nopti")) {
pti_print_if_insecure("disabled on command line.");
return;
}
autosel:
if (!boot_cpu_has_bug(X86_BUG_CPU_INSECURE))
return;
enable:
setup_force_cpu_cap(X86_FEATURE_PTI);
}