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x86/fpu: Parse clearcpuid= as early XSAVE argument

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With a followon patch we want to make clearcpuid affect the XSAVE
configuration. But xsave is currently initialized before arguments
are parsed. Move the clearcpuid= parsing into the special
early xsave argument parsing code.

Since clearcpuid= contains a = we need to keep the old __setup
around as a dummy, otherwise it would end up as a environment
variable in init's environment.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20171013215645.23166-4-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andi Kleen 2017-10-13 14:56:43 -07:00 committed by Ingo Molnar
parent 0b00de857a
commit 0c2a3913d6
2 changed files with 18 additions and 9 deletions
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16
arch/x86/kernel/cpu/common.c
View File

@ -1301,18 +1301,16 @@ void print_cpu_info(struct cpuinfo_x86 *c)
pr_cont(")\n");
}
static __init int setup_disablecpuid(char *arg)
/*
* clearcpuid= was already parsed in fpu__init_parse_early_param.
* But we need to keep a dummy __setup around otherwise it would
* show up as an environment variable for init.
*/
static __init int setup_clearcpuid(char *arg)
{
int bit;
if (get_option(&arg, &bit) && bit >= 0 && bit < NCAPINTS * 32)
setup_clear_cpu_cap(bit);
else
return 0;
return 1;
}
__setup("clearcpuid=", setup_disablecpuid);
__setup("clearcpuid=", setup_clearcpuid);
#ifdef CONFIG_X86_64
DEFINE_PER_CPU_FIRST(union irq_stack_union,

11
arch/x86/kernel/fpu/init.c
View File

@ -249,6 +249,10 @@ static void __init fpu__init_system_ctx_switch(void)
*/
static void __init fpu__init_parse_early_param(void)
{
char arg[32];
char *argptr = arg;
int bit;
if (cmdline_find_option_bool(boot_command_line, "no387"))
setup_clear_cpu_cap(X86_FEATURE_FPU);
@ -266,6 +270,13 @@ static void __init fpu__init_parse_early_param(void)
if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
setup_clear_cpu_cap(X86_FEATURE_XSAVES);
if (cmdline_find_option(boot_command_line, "clearcpuid", arg,
sizeof(arg)) &&
get_option(&argptr, &bit) &&
bit >= 0 &&
bit < NCAPINTS * 32)
setup_clear_cpu_cap(bit);
}
/*