diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/bits32/eflags.rs | 28 | ||||
| -rw-r--r-- | src/bits64/rflags.rs | 3 |
2 files changed, 31 insertions, 0 deletions
diff --git a/src/bits32/eflags.rs b/src/bits32/eflags.rs index a98b22a..4e073ec 100644 --- a/src/bits32/eflags.rs +++ b/src/bits32/eflags.rs @@ -77,3 +77,31 @@ pub unsafe fn read() -> EFlags { pub unsafe fn set(val: EFlags) { asm!("pushl $0; popfl" :: "r"(val.bits()) : "memory" "flags"); } + +/// Clears the AC flag bit in EFLAGS register. +/// +/// This disables any alignment checking of user-mode data accesses. +/// If the SMAP bit is set in the CR4 register, this disallows +/// explicit supervisor-mode data accesses to user-mode pages. +/// +/// # Unsafe +/// +/// This instruction is only valid in Ring 0 and requires +/// that the CPU supports the instruction (check CPUID). +pub unsafe fn clac() { + asm!("clac" ::: "memory" "flags" : "volatile"); +} + +/// Sets the AC flag bit in EFLAGS register. +/// +/// This may enable alignment checking of user-mode data accesses. +/// This allows explicit supervisor-mode data accesses to user-mode +/// pages even if the SMAP bit is set in the CR4 register. +/// +/// # Unsafe +/// +/// This instruction is only valid in Ring 0 and requires +/// that the CPU supports the instruction (check CPUID). +pub unsafe fn stac() { + asm!("stac" ::: "memory" "flags" : "volatile"); +}
\ No newline at end of file diff --git a/src/bits64/rflags.rs b/src/bits64/rflags.rs index 4c7deea..5f6fa11 100644 --- a/src/bits64/rflags.rs +++ b/src/bits64/rflags.rs @@ -86,3 +86,6 @@ pub unsafe fn read() -> RFlags { pub unsafe fn set(val: RFlags) { asm!("pushq $0; popfq" :: "r"(val.bits()) : "memory" "flags"); } + +// clac and stac are also usable in 64-bit mode +pub use crate::bits32::eflags::{clac, stac}; |