[Xen-changelog] reenable TS flag after testing for fdiv bug. fix the fpu corruption that some config have

[BitKeeper Bot <riel@xxxxxxxxxxx>]

ChangeSet 1.1159.258.164, 2005/06/08 18:14:35+01:00, 
vh249@xxxxxxxxxxxxxxxxxxxxxx

        reenable TS flag after testing for fdiv bug. fix the fpu corruption 
that some config have
        
        Signed-off: Vincent Hanquez <vincent@xxxxxxxxxxxxx>



 bugs.h |  214 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 214 insertions(+)


diff -Nru a/linux-2.6.11-xen-sparse/include/asm-xen/asm-i386/bugs.h 
b/linux-2.6.11-xen-sparse/include/asm-xen/asm-i386/bugs.h
--- /dev/null   Wed Dec 31 16:00:00 196900
+++ b/linux-2.6.11-xen-sparse/include/asm-xen/asm-i386/bugs.h   2005-06-08 
18:03:07 -04:00
@@ -0,0 +1,214 @@
+/*
+ *  include/asm-i386/bugs.h
+ *
+ *  Copyright (C) 1994  Linus Torvalds
+ *
+ *  Cyrix stuff, June 1998 by:
+ *     - Rafael R. Reilova (moved everything from head.S),
+ *        <rreilova@xxxxxxxxxxxx>
+ *     - Channing Corn (tests & fixes),
+ *     - Andrew D. Balsa (code cleanup).
+ *
+ *  Pentium III FXSR, SSE support
+ *     Gareth Hughes <gareth@xxxxxxxxxxx>, May 2000
+ */
+
+/*
+ * This is included by init/main.c to check for architecture-dependent bugs.
+ *
+ * Needs:
+ *     void check_bugs(void);
+ */
+
+#include <linux/config.h>
+#include <linux/init.h>
+#include <asm/processor.h>
+#include <asm/i387.h>
+#include <asm/msr.h>
+
+static int __init no_halt(char *s)
+{
+       boot_cpu_data.hlt_works_ok = 0;
+       return 1;
+}
+
+__setup("no-hlt", no_halt);
+
+static int __init mca_pentium(char *s)
+{
+       mca_pentium_flag = 1;
+       return 1;
+}
+
+__setup("mca-pentium", mca_pentium);
+
+static int __init no_387(char *s)
+{
+       boot_cpu_data.hard_math = 0;
+       write_cr0(0xE | read_cr0());
+       return 1;
+}
+
+__setup("no387", no_387);
+
+static double __initdata x = 4195835.0;
+static double __initdata y = 3145727.0;
+
+/*
+ * This used to check for exceptions.. 
+ * However, it turns out that to support that,
+ * the XMM trap handlers basically had to
+ * be buggy. So let's have a correct XMM trap
+ * handler, and forget about printing out
+ * some status at boot.
+ *
+ * We should really only care about bugs here
+ * anyway. Not features.
+ */
+static void __init check_fpu(void)
+{
+       if (!boot_cpu_data.hard_math) {
+#ifndef CONFIG_MATH_EMULATION
+               printk(KERN_EMERG "No coprocessor found and no math emulation 
present.\n");
+               printk(KERN_EMERG "Giving up.\n");
+               for (;;) ;
+#endif
+               return;
+       }
+
+/* Enable FXSR and company _before_ testing for FP problems. */
+       /*
+        * Verify that the FXSAVE/FXRSTOR data will be 16-byte aligned.
+        */
+       if (offsetof(struct task_struct, thread.i387.fxsave) & 15) {
+               extern void __buggy_fxsr_alignment(void);
+               __buggy_fxsr_alignment();
+       }
+       if (cpu_has_fxsr) {
+               printk(KERN_INFO "Enabling fast FPU save and restore... ");
+               set_in_cr4(X86_CR4_OSFXSR);
+               printk("done.\n");
+       }
+       if (cpu_has_xmm) {
+               printk(KERN_INFO "Enabling unmasked SIMD FPU exception 
support... ");
+               set_in_cr4(X86_CR4_OSXMMEXCPT);
+               printk("done.\n");
+       }
+
+       /* Test for the divl bug.. */
+       __asm__("fninit\n\t"
+               "fldl %1\n\t"
+               "fdivl %2\n\t"
+               "fmull %2\n\t"
+               "fldl %1\n\t"
+               "fsubp %%st,%%st(1)\n\t"
+               "fistpl %0\n\t"
+               "fwait\n\t"
+               "fninit"
+               : "=m" (*&boot_cpu_data.fdiv_bug)
+               : "m" (*&x), "m" (*&y));
+       stts();
+       if (boot_cpu_data.fdiv_bug)
+               printk("Hmm, FPU with FDIV bug.\n");
+}
+
+static void __init check_hlt(void)
+{
+       printk(KERN_INFO "Checking 'hlt' instruction... ");
+       if (!boot_cpu_data.hlt_works_ok) {
+               printk("disabled\n");
+               return;
+       }
+       __asm__ __volatile__("hlt ; hlt ; hlt ; hlt");
+       printk("OK.\n");
+}
+
+/*
+ *     Most 386 processors have a bug where a POPAD can lock the 
+ *     machine even from user space.
+ */
+ 
+static void __init check_popad(void)
+{
+#ifndef CONFIG_X86_POPAD_OK
+       int res, inp = (int) &res;
+
+       printk(KERN_INFO "Checking for popad bug... ");
+       __asm__ __volatile__( 
+         "movl $12345678,%%eax; movl $0,%%edi; pusha; popa; movl 
(%%edx,%%edi),%%ecx "
+         : "=&a" (res)
+         : "d" (inp)
+         : "ecx", "edi" );
+       /* If this fails, it means that any user program may lock the CPU hard. 
Too bad. */
+       if (res != 12345678) printk( "Buggy.\n" );
+                       else printk( "OK.\n" );
+#endif
+}
+
+/*
+ * Check whether we are able to run this kernel safely on SMP.
+ *
+ * - In order to run on a i386, we need to be compiled for i386
+ *   (for due to lack of "invlpg" and working WP on a i386)
+ * - In order to run on anything without a TSC, we need to be
+ *   compiled for a i486.
+ * - In order to support the local APIC on a buggy Pentium machine,
+ *   we need to be compiled with CONFIG_X86_GOOD_APIC disabled,
+ *   which happens implicitly if compiled for a Pentium or lower
+ *   (unless an advanced selection of CPU features is used) as an
+ *   otherwise config implies a properly working local APIC without
+ *   the need to do extra reads from the APIC.
+*/
+
+static void __init check_config(void)
+{
+/*
+ * We'd better not be a i386 if we're configured to use some
+ * i486+ only features! (WP works in supervisor mode and the
+ * new "invlpg" and "bswap" instructions)
+ */
+#if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || 
defined(CONFIG_X86_BSWAP)
+       if (boot_cpu_data.x86 == 3)
+               panic("Kernel requires i486+ for 'invlpg' and other features");
+#endif
+
+/*
+ * If we configured ourselves for a TSC, we'd better have one!
+ */
+#ifdef CONFIG_X86_TSC
+       if (!cpu_has_tsc)
+               panic("Kernel compiled for Pentium+, requires TSC feature!");
+#endif
+
+/*
+ * If we were told we had a good local APIC, check for buggy Pentia,
+ * i.e. all B steppings and the C2 stepping of P54C when using their
+ * integrated APIC (see 11AP erratum in "Pentium Processor
+ * Specification Update").
+ */
+#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_GOOD_APIC)
+       if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL
+           && cpu_has_apic
+           && boot_cpu_data.x86 == 5
+           && boot_cpu_data.x86_model == 2
+           && (boot_cpu_data.x86_mask < 6 || boot_cpu_data.x86_mask == 11))
+               panic("Kernel compiled for PMMX+, assumes a local APIC without 
the read-before-write bug!");
+#endif
+}
+
+extern void alternative_instructions(void);
+
+static void __init check_bugs(void)
+{
+       identify_cpu(&boot_cpu_data);
+#ifndef CONFIG_SMP
+       printk("CPU: ");
+       print_cpu_info(&boot_cpu_data);
+#endif
+       check_config();
+       check_fpu();
+       check_hlt();
+       check_popad();
+       system_utsname.machine[1] = '0' + (boot_cpu_data.x86 > 6 ? 6 : 
boot_cpu_data.x86);
+       alternative_instructions(); 
+}

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