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Use CPUID to see if the current CPU supports long mode when attemping to

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boot an amd64 kernel.  If not, then fail the boot request with an error
message.  Otherwise, the boot attempt will fail with a BTX fault when
trying to read the EFER MSR.

MFC after:	3 days
This commit is contained in:
John Baldwin 2008-10-07 14:05:42 +00:00
parent 8c3bc1af40
commit f252d86740
1 changed files with 47 additions and 1 deletions
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48
sys/boot/i386/libi386/bootinfo64.c
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@ -32,6 +32,9 @@ __FBSDID("$FreeBSD$");
#include <sys/reboot.h>
#include <sys/linker.h>
#include <machine/bootinfo.h>
#include <machine/cpufunc.h>
#include <machine/psl.h>
#include <machine/specialreg.h>
#include "bootstrap.h"
#include "libi386.h"
#include "btxv86.h"
@ -124,7 +127,45 @@ bi_copymodules64(vm_offset_t addr)
}
/*
* Load the information expected by an i386 kernel.
* Check to see if this CPU supports long mode.
*/
static int
bi_checkcpu(void)
{
char *cpu_vendor;
int vendor[3];
int eflags, regs[4];
/* Check for presence of "cpuid". */
eflags = read_eflags();
write_eflags(eflags ^ PSL_ID);
if (!((eflags ^ read_eflags()) & PSL_ID))
return (0);
/* Fetch the vendor string. */
do_cpuid(0, regs);
vendor[0] = regs[1];
vendor[1] = regs[3];
vendor[2] = regs[2];
cpu_vendor = (char *)vendor;
/* Check for vendors that support AMD features. */
if (strncmp(cpu_vendor, "GenuineIntel", 12) != 0 &&
strncmp(cpu_vendor, "AuthenticAMD", 12) != 0)
return (0);
/* Has to support AMD features. */
do_cpuid(0x80000000, regs);
if (!(regs[0] >= 0x80000001))
return (0);
/* Check for long mode. */
do_cpuid(0x80000001, regs);
return (regs[3] & AMDID_LM);
}
/*
* Load the information expected by an amd64 kernel.
*
* - The 'boothowto' argument is constructed
* - The 'bootdev' argument is constructed
@ -145,6 +186,11 @@ bi_load64(char *args, vm_offset_t *modulep, vm_offset_t *kernendp)
char *rootdevname;
int howto;
if (!bi_checkcpu()) {
printf("CPU doesn't support long mode\n");
return (EINVAL);
}
howto = bi_getboothowto(args);
/*