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Subject[tip: x86/fpu] x86/fpu: Handle FPU-related and clearcpuid command line arguments earlier
The following commit has been merged into the x86/fpu branch of tip:

Commit-ID: 1ef5423a55c2ac6f1361811efe75b6e46d1023ed
Gitweb: https://git.kernel.org/tip/1ef5423a55c2ac6f1361811efe75b6e46d1023ed
Author: Mike Hommey <mh@glandium.org>
AuthorDate: Tue, 22 Sep 2020 06:56:38 +09:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Tue, 22 Sep 2020 00:24:27 +02:00

x86/fpu: Handle FPU-related and clearcpuid command line arguments earlier

FPU initialization handles them currently. However, in the case
of clearcpuid=, some other early initialization code may check for
features before the FPU initialization code is called. Handling the
argument earlier allows the command line to influence those early
initializations.

Signed-off-by: Mike Hommey <mh@glandium.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200921215638.37980-1-mh@glandium.org
---
arch/x86/kernel/cpu/common.c | 55 +++++++++++++++++++++++++++++++++++-
arch/x86/kernel/fpu/init.c | 55 +-----------------------------------
2 files changed, 55 insertions(+), 55 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c5d6f17..3c75193 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -23,6 +23,7 @@
#include <linux/syscore_ops.h>
#include <linux/pgtable.h>

+#include <asm/cmdline.h>
#include <asm/stackprotector.h>
#include <asm/perf_event.h>
#include <asm/mmu_context.h>
@@ -1221,6 +1222,59 @@ static void detect_nopl(void)
}

/*
+ * We parse cpu parameters early because fpu__init_system() is executed
+ * before parse_early_param().
+ */
+static void __init cpu_parse_early_param(void)
+{
+ char arg[128];
+ char *argptr = arg;
+ int arglen, res, bit;
+
+#ifdef CONFIG_X86_32
+ if (cmdline_find_option_bool(boot_command_line, "no387"))
+#ifdef CONFIG_MATH_EMULATION
+ setup_clear_cpu_cap(X86_FEATURE_FPU);
+#else
+ pr_err("Option 'no387' required CONFIG_MATH_EMULATION enabled.\n");
+#endif
+
+ if (cmdline_find_option_bool(boot_command_line, "nofxsr"))
+ setup_clear_cpu_cap(X86_FEATURE_FXSR);
+#endif
+
+ if (cmdline_find_option_bool(boot_command_line, "noxsave"))
+ setup_clear_cpu_cap(X86_FEATURE_XSAVE);
+
+ if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
+ setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
+
+ if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
+ setup_clear_cpu_cap(X86_FEATURE_XSAVES);
+
+ arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));
+ if (arglen <= 0)
+ return;
+
+ pr_info("Clearing CPUID bits:");
+ do {
+ res = get_option(&argptr, &bit);
+ if (res == 0 || res == 3)
+ break;
+
+ /* If the argument was too long, the last bit may be cut off */
+ if (res == 1 && arglen >= sizeof(arg))
+ break;
+
+ if (bit >= 0 && bit < NCAPINTS * 32) {
+ pr_cont(" " X86_CAP_FMT, x86_cap_flag(bit));
+ setup_clear_cpu_cap(bit);
+ }
+ } while (res == 2);
+ pr_cont("\n");
+}
+
+/*
* Do minimum CPU detection early.
* Fields really needed: vendor, cpuid_level, family, model, mask,
* cache alignment.
@@ -1255,6 +1309,7 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
get_cpu_cap(c);
get_cpu_address_sizes(c);
setup_force_cpu_cap(X86_FEATURE_CPUID);
+ cpu_parse_early_param();

if (this_cpu->c_early_init)
this_cpu->c_early_init(c);
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index f8ff895..701f196 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -5,7 +5,6 @@
#include <asm/fpu/internal.h>
#include <asm/tlbflush.h>
#include <asm/setup.h>
-#include <asm/cmdline.h>

#include <linux/sched.h>
#include <linux/sched/task.h>
@@ -238,65 +237,11 @@ static void __init fpu__init_system_ctx_switch(void)
}

/*
- * We parse fpu parameters early because fpu__init_system() is executed
- * before parse_early_param().
- */
-static void __init fpu__init_parse_early_param(void)
-{
- char arg[128];
- char *argptr = arg;
- int arglen, res, bit;
-
-#ifdef CONFIG_X86_32
- if (cmdline_find_option_bool(boot_command_line, "no387"))
-#ifdef CONFIG_MATH_EMULATION
- setup_clear_cpu_cap(X86_FEATURE_FPU);
-#else
- pr_err("Option 'no387' required CONFIG_MATH_EMULATION enabled.\n");
-#endif
-
- if (cmdline_find_option_bool(boot_command_line, "nofxsr"))
- setup_clear_cpu_cap(X86_FEATURE_FXSR);
-#endif
-
- if (cmdline_find_option_bool(boot_command_line, "noxsave"))
- setup_clear_cpu_cap(X86_FEATURE_XSAVE);
-
- if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
- setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
-
- if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
- setup_clear_cpu_cap(X86_FEATURE_XSAVES);
-
- arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));
- if (arglen <= 0)
- return;
-
- pr_info("Clearing CPUID bits:");
- do {
- res = get_option(&argptr, &bit);
- if (res == 0 || res == 3)
- break;
-
- /* If the argument was too long, the last bit may be cut off */
- if (res == 1 && arglen >= sizeof(arg))
- break;
-
- if (bit >= 0 && bit < NCAPINTS * 32) {
- pr_cont(" " X86_CAP_FMT, x86_cap_flag(bit));
- setup_clear_cpu_cap(bit);
- }
- } while (res == 2);
- pr_cont("\n");
-}
-
-/*
* Called on the boot CPU once per system bootup, to set up the initial
* FPU state that is later cloned into all processes:
*/
void __init fpu__init_system(struct cpuinfo_x86 *c)
{
- fpu__init_parse_early_param();
fpu__init_system_early_generic(c);

/*
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