renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2025-01-11 15:14:03 +08:00
Code
4b6b9111c0
linux-next/arch/x86/include/asm/doublefault.h

14 lines
271 B
C
Raw Normal View History

x86/doublefault/32: Move #DF stack and TSS to cpu_entry_area There are three problems with the current layout of the doublefault stack and TSS. First, the TSS is only cacheline-aligned, which is not enough -- if the hardware portion of the TSS (struct x86_hw_tss) crosses a page boundary, horrible things happen [0]. Second, the stack and TSS are global, so simultaneous double faults on different CPUs will cause massive corruption. Third, the whole mechanism won't work if user CR3 is loaded, resulting in a triple fault [1]. Let the doublefault stack and TSS share a page (which prevents the TSS from spanning a page boundary), make it percpu, and move it into cpu_entry_area. Teach the stack dump code about the doublefault stack. [0] Real hardware will read past the end of the page onto the next *physical* page if a task switch happens. Virtual machines may have any number of bugs, and I would consider it reasonable for a VM to summarily kill the guest if it tries to task-switch to a page-spanning TSS. [1] Real hardware triple faults. At least some VMs seem to hang. I'm not sure what's going on. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-27 01:27:16 +08:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_DOUBLEFAULT_H
#define _ASM_X86_DOUBLEFAULT_H
x86/32: Remove CONFIG_DOUBLEFAULT Make the doublefault exception handler unconditional on 32-bit. Yes, it is important to be able to catch #DF exceptions instead of silent reboots. Yes, the code size increase is worth every byte. And one less CONFIG symbol is just the cherry on top. No functional changes. Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200404083646.8897-1-bp@alien8.de
2020-04-04 07:33:05 +08:00
#ifdef CONFIG_X86_32
x86/doublefault/32: Move #DF stack and TSS to cpu_entry_area There are three problems with the current layout of the doublefault stack and TSS. First, the TSS is only cacheline-aligned, which is not enough -- if the hardware portion of the TSS (struct x86_hw_tss) crosses a page boundary, horrible things happen [0]. Second, the stack and TSS are global, so simultaneous double faults on different CPUs will cause massive corruption. Third, the whole mechanism won't work if user CR3 is loaded, resulting in a triple fault [1]. Let the doublefault stack and TSS share a page (which prevents the TSS from spanning a page boundary), make it percpu, and move it into cpu_entry_area. Teach the stack dump code about the doublefault stack. [0] Real hardware will read past the end of the page onto the next *physical* page if a task switch happens. Virtual machines may have any number of bugs, and I would consider it reasonable for a VM to summarily kill the guest if it tries to task-switch to a page-spanning TSS. [1] Real hardware triple faults. At least some VMs seem to hang. I'm not sure what's going on. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-27 01:27:16 +08:00
extern void doublefault_init_cpu_tss(void);
#else
static inline void doublefault_init_cpu_tss(void)
{
}
#endif
#endif /* _ASM_X86_DOUBLEFAULT_H */
Copy Permalink