ebc14ddcc9
According to the Intel SDM vol 3A (order code 253668-051US, June 2014), on section 9.11.1, page 9-28: "For microcode updates with a data size field equal to 00000000H, the size of the microcode update is 2048 bytes. The first 48 bytes contain the microcode update header. The remaining 2000 bytes contain encrypted data." "For microcode updates with a data size not equal to 00000000H, the total size field specifies the size of the microcode update." Up to 2002/2003, Intel used an "old format" for the microcode update containers that was always 2048 bytes in size. That old format did not have Data Size and Total Size fields, the quadwords at those positions in the microcode container header were "reserved". The microcode header of the "old format" microcode container has a hrdver of 0x01. You can hunt down an old copy of the Intel SDM to validate this through its order number (#243192). I found one from 1999 through a Google search. Sometime in 2002/2003 (AFAICT, for the Prescott processors), Intel documented a new format for the microcode containers and contributed in 2003 some code to the Linux kernel microcode driver implementing support for the new format. This new format has Data Size and Total Size fields, as well as the optional extended signature table. However, it reuses the same hrdver as the old format (0x01), and it can only be told apart from the old format by a non-zero Data Size field. In fact, the only reason we can even trust a Data Size of zero to mean that the microcode container is in the old format, is because Intel reatroatively promised that the old format would always have a zero there when they wrote the documentation for the _new_ format. This is a very old bug, dating back to 2003. It has been dormant ever since, as Intel seems to set all reserved fields to zero on the microcode updates they distribute: I could not find a public microcode update that would trigger this bug. Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Link: http://lkml.kernel.org/r/1406146251-8540-1-git-send-email-hmh@hmh.eng.br Signed-off-by: Borislav Petkov <bp@suse.de>
88 lines
2.7 KiB
C
88 lines
2.7 KiB
C
#ifndef _ASM_X86_MICROCODE_INTEL_H
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#define _ASM_X86_MICROCODE_INTEL_H
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#include <asm/microcode.h>
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struct microcode_header_intel {
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unsigned int hdrver;
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unsigned int rev;
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unsigned int date;
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unsigned int sig;
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unsigned int cksum;
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unsigned int ldrver;
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unsigned int pf;
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unsigned int datasize;
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unsigned int totalsize;
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unsigned int reserved[3];
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};
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struct microcode_intel {
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struct microcode_header_intel hdr;
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unsigned int bits[0];
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};
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/* microcode format is extended from prescott processors */
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struct extended_signature {
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unsigned int sig;
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unsigned int pf;
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unsigned int cksum;
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};
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struct extended_sigtable {
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unsigned int count;
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unsigned int cksum;
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unsigned int reserved[3];
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struct extended_signature sigs[0];
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};
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#define DEFAULT_UCODE_DATASIZE (2000)
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#define MC_HEADER_SIZE (sizeof(struct microcode_header_intel))
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#define DEFAULT_UCODE_TOTALSIZE (DEFAULT_UCODE_DATASIZE + MC_HEADER_SIZE)
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#define EXT_HEADER_SIZE (sizeof(struct extended_sigtable))
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#define EXT_SIGNATURE_SIZE (sizeof(struct extended_signature))
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#define DWSIZE (sizeof(u32))
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#define get_totalsize(mc) \
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(((struct microcode_intel *)mc)->hdr.datasize ? \
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((struct microcode_intel *)mc)->hdr.totalsize : \
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DEFAULT_UCODE_TOTALSIZE)
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#define get_datasize(mc) \
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(((struct microcode_intel *)mc)->hdr.datasize ? \
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((struct microcode_intel *)mc)->hdr.datasize : DEFAULT_UCODE_DATASIZE)
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#define sigmatch(s1, s2, p1, p2) \
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(((s1) == (s2)) && (((p1) & (p2)) || (((p1) == 0) && ((p2) == 0))))
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#define exttable_size(et) ((et)->count * EXT_SIGNATURE_SIZE + EXT_HEADER_SIZE)
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extern int
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get_matching_microcode(unsigned int csig, int cpf, void *mc, int rev);
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extern int microcode_sanity_check(void *mc, int print_err);
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extern int get_matching_sig(unsigned int csig, int cpf, void *mc, int rev);
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extern int
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update_match_revision(struct microcode_header_intel *mc_header, int rev);
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#ifdef CONFIG_MICROCODE_INTEL_EARLY
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extern void __init load_ucode_intel_bsp(void);
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extern void load_ucode_intel_ap(void);
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extern void show_ucode_info_early(void);
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extern int __init save_microcode_in_initrd_intel(void);
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#else
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static inline __init void load_ucode_intel_bsp(void) {}
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static inline void load_ucode_intel_ap(void) {}
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static inline void show_ucode_info_early(void) {}
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static inline int __init save_microcode_in_initrd_intel(void) { return -EINVAL; }
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#endif
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#if defined(CONFIG_MICROCODE_INTEL_EARLY) && defined(CONFIG_HOTPLUG_CPU)
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extern int save_mc_for_early(u8 *mc);
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#else
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static inline int save_mc_for_early(u8 *mc)
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{
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return 0;
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}
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#endif
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#endif /* _ASM_X86_MICROCODE_INTEL_H */
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