103 lines
2.9 KiB
C
103 lines
2.9 KiB
C
/* rdmsr.c - Read 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/rdmsr.h>
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GRUB_MOD_LICENSE("GPLv3+");
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static grub_extcmd_t cmd_read;
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static const struct grub_arg_option options[] =
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{
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{0, 'v', 0, N_("Save read value into variable VARNAME."),
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N_("VARNAME"), ARG_TYPE_STRING},
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{0, 0, 0, 0, 0, 0}
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};
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static grub_err_t
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grub_cmd_msr_read (grub_extcmd_context_t ctxt, 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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char buf[sizeof("1122334455667788")];
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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 != 1)
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return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument 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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value = grub_msr_read (addr);
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if (ctxt->state[0].set)
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{
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grub_snprintf (buf, sizeof(buf), "%llx", (unsigned long long) value);
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grub_env_set (ctxt->state[0].arg, buf);
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}
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else
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grub_printf ("0x%llx\n", (unsigned long long) value);
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return GRUB_ERR_NONE;
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}
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GRUB_MOD_INIT(rdmsr)
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{
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cmd_read = grub_register_extcmd ("rdmsr", grub_cmd_msr_read, 0, N_("ADDR"),
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N_("Read a CPU model specific register."),
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options);
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}
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GRUB_MOD_FINI(rdmsr)
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{
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grub_unregister_extcmd (cmd_read);
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}
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