diff options
| author |   Andy Lutomirski <luto@kernel.org> | 2021-01-19 09:40:55 -0800 |
|---|---|---|
| committer |   Borislav Petkov <bp@suse.de> | 2021-01-21 20:08:53 +0100 |
| commit | 8ece53ef7f428ee3f8eab936268b1a3fe2725e6b (patch) | |
| tree | d301122cac7f7b02c221441b4824b91144b0ec80 /arch/x86/mm/fault.c | |
| parent | x86: Remove definition of DEBUG (diff) | |
| download | linux-dev-8ece53ef7f428ee3f8eab936268b1a3fe2725e6b.tar.xz linux-dev-8ece53ef7f428ee3f8eab936268b1a3fe2725e6b.zip | |
x86/vm86/32: Remove VM86_SCREEN_BITMAP support
The implementation was rather buggy. It unconditionally marked PTEs
read-only, even for VM_SHARED mappings. I'm not sure whether this is
actually a problem, but it certainly seems unwise. More importantly, it
released the mmap lock before flushing the TLB, which could allow a racing
CoW operation to falsely believe that the underlying memory was not
writable.
I can't find any users at all of this mechanism, so just remove it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Stas Sergeev <stsp2@yandex.ru>
Link: https://lkml.kernel.org/r/f3086de0babcab36f69949b5780bde851f719bc8.1611078018.git.luto@kernel.org
Diffstat (limited to 'arch/x86/mm/fault.c')
| -rw-r--r-- | arch/x86/mm/fault.c | 30 |
1 files changed, 0 insertions, 30 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index f1f1b5a0956a..106b22d1d189 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -262,25 +262,6 @@ void arch_sync_kernel_mappings(unsigned long start, unsigned long end) } } -/* - * Did it hit the DOS screen memory VA from vm86 mode? - */ -static inline void -check_v8086_mode(struct pt_regs *regs, unsigned long address, - struct task_struct *tsk) -{ -#ifdef CONFIG_VM86 - unsigned long bit; - - if (!v8086_mode(regs) || !tsk->thread.vm86) - return; - - bit = (address - 0xA0000) >> PAGE_SHIFT; - if (bit < 32) - tsk->thread.vm86->screen_bitmap |= 1 << bit; -#endif -} - static bool low_pfn(unsigned long pfn) { return pfn < max_low_pfn; @@ -335,15 +316,6 @@ KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n"; #endif -/* - * No vm86 mode in 64-bit mode: - */ -static inline void -check_v8086_mode(struct pt_regs *regs, unsigned long address, - struct task_struct *tsk) -{ -} - static int bad_address(void *p) { unsigned long dummy; @@ -1416,8 +1388,6 @@ good_area: mm_fault_error(regs, hw_error_code, address, fault); return; } - - check_v8086_mode(regs, address, tsk); } NOKPROBE_SYMBOL(do_user_addr_fault); |