94 lines
2.7 KiB
C
94 lines
2.7 KiB
C
/* wrmsr.c - Write CPU model-specific registers. */
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/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2019 Free Software Foundation, Inc.
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* Based on gcc/gcc/config/i386/driver-i386.c
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <grub/dl.h>
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#include <grub/misc.h>
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#include <grub/mm.h>
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#include <grub/env.h>
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#include <grub/command.h>
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#include <grub/extcmd.h>
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#include <grub/i18n.h>
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#include <grub/i386/cpuid.h>
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#include <grub/i386/wrmsr.h>
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GRUB_MOD_LICENSE("GPLv3+");
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static grub_command_t cmd_write;
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static grub_err_t
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grub_cmd_msr_write (grub_command_t cmd __attribute__ ((unused)), int argc, char **argv)
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{
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grub_uint32_t manufacturer[3], max_cpuid, a, b, c, features, addr;
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grub_uint64_t value;
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const char *ptr;
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/*
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* The CPUID instruction should be used to determine whether MSRs
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* are supported. (CPUID.01H:EDX[5] = 1)
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*/
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if (!grub_cpu_is_cpuid_supported ())
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return grub_error (GRUB_ERR_BUG, N_("unsupported instruction"));
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grub_cpuid (0, max_cpuid, manufacturer[0], manufacturer[2], manufacturer[1]);
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if (max_cpuid < 1)
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return grub_error (GRUB_ERR_BUG, N_("unsupported instruction"));
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grub_cpuid (1, a, b, c, features);
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if (!(features & (1 << 5)))
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return grub_error (GRUB_ERR_BUG, N_("unsupported instruction"));
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if (argc != 2)
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return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments expected"));
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grub_errno = GRUB_ERR_NONE;
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ptr = argv[0];
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addr = grub_strtoul (ptr, &ptr, 0);
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if (grub_errno != GRUB_ERR_NONE)
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return grub_errno;
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if (*ptr != '\0')
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return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid argument"));
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ptr = argv[1];
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value = grub_strtoull (ptr, &ptr, 0);
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if (grub_errno != GRUB_ERR_NONE)
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return grub_errno;
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if (*ptr != '\0')
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return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid argument"));
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grub_msr_write (addr, value);
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return GRUB_ERR_NONE;
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}
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GRUB_MOD_INIT(wrmsr)
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{
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cmd_write = grub_register_command ("wrmsr", grub_cmd_msr_write, N_("ADDR VALUE"),
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N_("Write a value to a CPU model specific register."));
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}
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GRUB_MOD_FINI(wrmsr)
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{
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grub_unregister_command (cmd_write);
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}
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