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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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e6e5494cb2
Move the i386 VDSO down into a vma and thus randomize it. Besides the security implications, this feature also helps debuggers, which can COW a vma-backed VDSO just like a normal DSO and can thus do single-stepping and other debugging features. It's good for hypervisors (Xen, VMWare) too, which typically live in the same high-mapped address space as the VDSO, hence whenever the VDSO is used, they get lots of guest pagefaults and have to fix such guest accesses up - which slows things down instead of speeding things up (the primary purpose of the VDSO). There's a new CONFIG_COMPAT_VDSO (default=y) option, which provides support for older glibcs that still rely on a prelinked high-mapped VDSO. Newer distributions (using glibc 2.3.3 or later) can turn this option off. Turning it off is also recommended for security reasons: attackers cannot use the predictable high-mapped VDSO page as syscall trampoline anymore. There is a new vdso=[0|1] boot option as well, and a runtime /proc/sys/vm/vdso_enabled sysctl switch, that allows the VDSO to be turned on/off. (This version of the VDSO-randomization patch also has working ELF coredumping, the previous patch crashed in the coredumping code.) This code is a combined work of the exec-shield VDSO randomization code and Gerd Hoffmann's hypervisor-centric VDSO patch. Rusty Russell started this patch and i completed it. [akpm@osdl.org: cleanups] [akpm@osdl.org: compile fix] [akpm@osdl.org: compile fix 2] [akpm@osdl.org: compile fix 3] [akpm@osdl.org: revernt MAXMEM change] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@infradead.org> Cc: Gerd Hoffmann <kraxel@suse.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Zachary Amsden <zach@vmware.com> Cc: Andi Kleen <ak@muc.de> Cc: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
99 lines
2.7 KiB
C
99 lines
2.7 KiB
C
#ifndef _ASM_I386_UNWIND_H
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#define _ASM_I386_UNWIND_H
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/*
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* Copyright (C) 2002-2006 Novell, Inc.
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* Jan Beulich <jbeulich@novell.com>
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* This code is released under version 2 of the GNU GPL.
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*/
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#ifdef CONFIG_STACK_UNWIND
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#include <linux/sched.h>
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#include <asm/fixmap.h>
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#include <asm/ptrace.h>
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#include <asm/uaccess.h>
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struct unwind_frame_info
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{
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struct pt_regs regs;
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struct task_struct *task;
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};
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#define UNW_PC(frame) (frame)->regs.eip
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#define UNW_SP(frame) (frame)->regs.esp
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#ifdef CONFIG_FRAME_POINTER
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#define UNW_FP(frame) (frame)->regs.ebp
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#define FRAME_RETADDR_OFFSET 4
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#define FRAME_LINK_OFFSET 0
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#define STACK_BOTTOM(tsk) STACK_LIMIT((tsk)->thread.esp0)
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#define STACK_TOP(tsk) ((tsk)->thread.esp0)
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#endif
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#define STACK_LIMIT(ptr) (((ptr) - 1) & ~(THREAD_SIZE - 1))
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#define UNW_REGISTER_INFO \
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PTREGS_INFO(eax), \
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PTREGS_INFO(ecx), \
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PTREGS_INFO(edx), \
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PTREGS_INFO(ebx), \
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PTREGS_INFO(esp), \
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PTREGS_INFO(ebp), \
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PTREGS_INFO(esi), \
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PTREGS_INFO(edi), \
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PTREGS_INFO(eip)
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static inline void arch_unw_init_frame_info(struct unwind_frame_info *info,
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/*const*/ struct pt_regs *regs)
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{
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if (user_mode_vm(regs))
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info->regs = *regs;
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else {
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memcpy(&info->regs, regs, offsetof(struct pt_regs, esp));
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info->regs.esp = (unsigned long)®s->esp;
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info->regs.xss = __KERNEL_DS;
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}
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}
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static inline void arch_unw_init_blocked(struct unwind_frame_info *info)
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{
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memset(&info->regs, 0, sizeof(info->regs));
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info->regs.eip = info->task->thread.eip;
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info->regs.xcs = __KERNEL_CS;
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__get_user(info->regs.ebp, (long *)info->task->thread.esp);
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info->regs.esp = info->task->thread.esp;
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info->regs.xss = __KERNEL_DS;
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info->regs.xds = __USER_DS;
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info->regs.xes = __USER_DS;
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}
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extern asmlinkage int arch_unwind_init_running(struct unwind_frame_info *,
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asmlinkage int (*callback)(struct unwind_frame_info *,
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void *arg),
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void *arg);
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static inline int arch_unw_user_mode(const struct unwind_frame_info *info)
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{
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#if 0 /* This can only work when selector register and EFLAGS saves/restores
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are properly annotated (and tracked in UNW_REGISTER_INFO). */
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return user_mode_vm(&info->regs);
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#else
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return info->regs.eip < PAGE_OFFSET
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|| (info->regs.eip >= __fix_to_virt(FIX_VDSO)
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&& info->regs.eip < __fix_to_virt(FIX_VDSO) + PAGE_SIZE)
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|| info->regs.esp < PAGE_OFFSET;
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#endif
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}
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#else
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#define UNW_PC(frame) ((void)(frame), 0)
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static inline int arch_unw_user_mode(const void *info)
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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_I386_UNWIND_H */
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