[tip:x86/cpu] x86, cpu: Convert FDIV bug detection

tip-bot for Borislav Petkov
2013-04-02T19:35:46Z

Commit-ID: 93a829e8e2c292f1d30155f64803101ca1cb7d3d
Gitweb: http://git.kernel.org/tip/93a829e8e2c292f1d30155f64803101ca1cb7d3d
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Wed, 20 Mar 2013 15:07:25 +0100
Committer: H. Peter Anvin <hpa@zytor.com>
CommitDate: Tue, 2 Apr 2013 10:12:53 -0700

x86, cpu: Convert FDIV bug detection

... to the new facility. Add a reference to the wikipedia article
explaining the FDIV test we're doing here.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1363788448-31325-4-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
arch/x86/include/asm/cpufeature.h | 1 +
arch/x86/include/asm/processor.h | 1 -
arch/x86/kernel/cpu/bugs.c | 7 ++++---
arch/x86/kernel/cpu/proc.c | 2 +-
arch/x86/kernel/setup.c | 2 --
5 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index c0ad7e7..25eb948 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -223,6 +223,7 @@
#define X86_BUG(x) (NCAPINTS*32 + (x))

#define X86_BUG_F00F X86_BUG(0) /* Intel F00F */
+#define X86_BUG_FDIV X86_BUG(1) /* FPU FDIV */

#if defined(__KERNEL__) && !defined(__ASSEMBLY__)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 1e55e2d..ea22dfa 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -91,7 +91,6 @@ struct cpuinfo_x86 {
/* Problems on some 486Dx4's and old 386's: */
char hard_math;
char rfu;
- char fdiv_bug;
char coma_bug;
char pad0;
#else
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index af6455e..c59635e 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -59,7 +59,7 @@ static void __init check_fpu(void)
* trap_init() enabled FXSR and company _before_ testing for FP
* problems here.
*
- * Test for the divl bug..
+ * Test for the divl bug: http://en.wikipedia.org/wiki/Fdiv_bug
*/
__asm__("fninit\n\t"
"fldl %1\n\t"
@@ -75,9 +75,10 @@ static void __init check_fpu(void)

kernel_fpu_end();

- boot_cpu_data.fdiv_bug = fdiv_bug;
- if (boot_cpu_data.fdiv_bug)
+ if (fdiv_bug) {
+ set_cpu_bug(&boot_cpu_data, X86_BUG_FDIV);
pr_warn("Hmm, FPU with FDIV bug\n");
+ }
}

/*
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 2d60b2b..5dfb6c6 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -34,7 +34,7 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
"fpu_exception\t: %s\n"
"cpuid level\t: %d\n"
"wp\t\t: %s\n",
- c->fdiv_bug ? "yes" : "no",
+ static_cpu_has_bug(X86_BUG_FDIV) ? "yes" : "no",
static_cpu_has_bug(X86_BUG_F00F) ? "yes" : "no",
c->coma_bug ? "yes" : "no",
c->hard_math ? "yes" : "no",
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 90d8cc9..29258c75 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -173,12 +173,10 @@ static struct resource bss_resource = {
/* cpu data as detected by the assembly code in head.S */
struct cpuinfo_x86 new_cpu_data __cpuinitdata = {
.wp_works_ok = -1,
- .fdiv_bug = -1,
};
/* common cpu data for all cpus */
struct cpuinfo_x86 boot_cpu_data __read_mostly = {
.wp_works_ok = -1,
- .fdiv_bug = -1,
};
EXPORT_SYMBOL(boot_cpu_data);