ChangeSet 1.1898, 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
18:04:19 -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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