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tlb: don't mark writable on read access (otherwise the write bit might not be set if a read occurs before a write)

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Fabian 2022-09-13 15:16:12 +09:00
parent 5ea85077cc
commit 86fc542352
1 changed files with 15 additions and 22 deletions
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37
src/rust/cpu/cpu.rs
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@ -1876,7 +1876,6 @@ pub unsafe fn do_page_walk(
user: bool,
side_effects: bool,
) -> Result<u32, PageFault> {
let mut can_write: bool = true;
let global;
let mut allow_user: bool = true;
let page = (addr as u32 >> 12) as i32;
@ -1936,16 +1935,13 @@ pub unsafe fn do_page_walk(
}
let kernel_write_override = !user && 0 == cr0 & CR0_WP;
if page_dir_entry & PAGE_TABLE_RW_MASK == 0 && !kernel_write_override {
can_write = false;
if for_writing {
return Err(PageFault {
addr,
for_writing,
user,
present: true,
});
}
if page_dir_entry & PAGE_TABLE_RW_MASK == 0 && !kernel_write_override && for_writing {
return Err(PageFault {
addr,
for_writing,
user,
present: true,
});
}
if page_dir_entry & PAGE_TABLE_USER_MASK == 0 {
@ -2013,16 +2009,13 @@ pub unsafe fn do_page_walk(
});
}
if page_table_entry & PAGE_TABLE_RW_MASK == 0 && !kernel_write_override {
can_write = false;
if for_writing {
return Err(PageFault {
addr,
for_writing,
user,
present: true,
});
}
if page_table_entry & PAGE_TABLE_RW_MASK == 0 && !kernel_write_override && for_writing {
return Err(PageFault {
addr,
for_writing,
user,
present: true,
});
}
if page_table_entry & PAGE_TABLE_USER_MASK == 0 {
allow_user = false;
@ -2085,7 +2078,7 @@ pub unsafe fn do_page_walk(
let is_in_mapped_range = in_mapped_range(high);
let has_code = !is_in_mapped_range && jit::jit_page_has_code(Page::page_of(high));
let info_bits = TLB_VALID
| if can_write { 0 } else { TLB_READONLY }
| if for_writing { 0 } else { TLB_READONLY }
| if allow_user { 0 } else { TLB_NO_USER }
| if is_in_mapped_range { TLB_IN_MAPPED_RANGE } else { 0 }
| if global && 0 != cr4 & CR4_PGE { TLB_GLOBAL } else { 0 }