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x86/pti: Fix kernel warnings for pti= and nopti cmdline options

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Parse the pti= and nopti cmdline options using early_param to fix 'Unknown
kernel command line parameters "nopti", will be passed to user space'
warnings in the kernel log when nopti or pti= are passed to the kernel
cmdline on x86 platforms.

Additionally allow the kernel to warn for malformed pti= options.

Signed-off-by: Jo Van Bulck <jo.vanbulck@cs.kuleuven.be>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20230819080921.5324-2-jo.vanbulck@cs.kuleuven.be
This commit is contained in:
Jo Van Bulck 2023-08-19 10:09:21 +02:00 committed by Borislav Petkov (AMD)
parent 99ee56c765
commit 0bd7feb2df
1 changed files with 29 additions and 29 deletions
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58
arch/x86/mm/pti.c
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@ -69,6 +69,7 @@ static void __init pti_print_if_secure(const char *reason)
pr_info("%s\n", reason);
}
/* Assume mode is auto unless overridden via cmdline below. */
static enum pti_mode {
PTI_AUTO = 0,
PTI_FORCE_OFF,
@ -77,50 +78,49 @@ static enum pti_mode {
void __init pti_check_boottime_disable(void)
{
char arg[5];
int ret;
/* Assume mode is auto unless overridden. */
pti_mode = PTI_AUTO;
if (hypervisor_is_type(X86_HYPER_XEN_PV)) {
pti_mode = PTI_FORCE_OFF;
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_mode = PTI_FORCE_OFF;
pti_print_if_insecure("disabled on command line.");
return;
}
if (ret == 2 && !strncmp(arg, "on", 2)) {
pti_mode = PTI_FORCE_ON;
pti_print_if_secure("force enabled on command line.");
goto enable;
}
if (ret == 4 && !strncmp(arg, "auto", 4)) {
pti_mode = PTI_AUTO;
goto autosel;
}
}
if (cmdline_find_option_bool(boot_command_line, "nopti") ||
cpu_mitigations_off()) {
if (cpu_mitigations_off())
pti_mode = PTI_FORCE_OFF;
if (pti_mode == PTI_FORCE_OFF) {
pti_print_if_insecure("disabled on command line.");
return;
}
autosel:
if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
if (pti_mode == PTI_FORCE_ON)
pti_print_if_secure("force enabled on command line.");
if (pti_mode == PTI_AUTO && !boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
return;
enable:
setup_force_cpu_cap(X86_FEATURE_PTI);
}
static int __init pti_parse_cmdline(char *arg)
{
if (!strcmp(arg, "off"))
pti_mode = PTI_FORCE_OFF;
else if (!strcmp(arg, "on"))
pti_mode = PTI_FORCE_ON;
else if (!strcmp(arg, "auto"))
pti_mode = PTI_AUTO;
else
return -EINVAL;
return 0;
}
early_param("pti", pti_parse_cmdline);
static int __init pti_parse_cmdline_nopti(char *arg)
{
pti_mode = PTI_FORCE_OFF;
return 0;
}
early_param("nopti", pti_parse_cmdline_nopti);
pgd_t __pti_set_user_pgtbl(pgd_t *pgdp, pgd_t pgd)
{
/*