37868fe113
modify_ldt() has questionable locking and does not synchronize threads. Improve it: redesign the locking and synchronize all threads' LDTs using an IPI on all modifications. This will dramatically slow down modify_ldt in multithreaded programs, but there shouldn't be any multithreaded programs that care about modify_ldt's performance in the first place. This fixes some fallout from the CVE-2015-5157 fixes. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: security@kernel.org <security@kernel.org> Cc: <stable@vger.kernel.org> Cc: xen-devel <xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/4c6978476782160600471bd865b318db34c7b628.1438291540.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
34 lines
611 B
C
34 lines
611 B
C
#ifndef _ASM_X86_MMU_H
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#define _ASM_X86_MMU_H
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#include <linux/spinlock.h>
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#include <linux/mutex.h>
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/*
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* The x86 doesn't have a mmu context, but
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* we put the segment information here.
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*/
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typedef struct {
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struct ldt_struct *ldt;
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#ifdef CONFIG_X86_64
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/* True if mm supports a task running in 32 bit compatibility mode. */
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unsigned short ia32_compat;
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#endif
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struct mutex lock;
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void __user *vdso;
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atomic_t perf_rdpmc_allowed; /* nonzero if rdpmc is allowed */
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} mm_context_t;
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#ifdef CONFIG_SMP
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void leave_mm(int cpu);
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#else
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static inline void leave_mm(int cpu)
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{
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}
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#endif
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#endif /* _ASM_X86_MMU_H */
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