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| author |  Gerd Zellweger <mail@gerdzellweger.com>
| 2015-11-29 12:17:36 +0100 |
|---|---|---|
| committer | Gerd Zellweger <mail@gerdzellweger.com>
| 2015-11-29 12:17:36 +0100 |
| commit | 8ea2eb2dc442e9d0e89e08d40283b1aaba1cc87a (patch) | |
| tree | eaa63e77f9386864c26fb87a9f50f4628611abc8 /src/syscall.rs | |
| parent | bec7731473a0fae1d837a8a0fdfc902504ea9fcd (diff) | |
| download | rust-x86-8ea2eb2dc442e9d0e89e08d40283b1aaba1cc87a.tar.gz rust-x86-8ea2eb2dc442e9d0e89e08d40283b1aaba1cc87a.tar.zst rust-x86-8ea2eb2dc442e9d0e89e08d40283b1aaba1cc87a.zip | |
Fixing volatile and memory attributes for assembly.
For volatile:
You can prevent an asm instruction from being deleted by writing the
keyword volatile after the asm. [...] The volatile keyword indicates
that the instruction has important side-effects. GCC will not
delete a volatile asm if it is reachable.
and
An asm instruction without any output operands will be treated
identically to a volatile asm instruction.
And for memory:
This will cause GCC to not keep memory values cached in
registers across the assembler instruction and not optimize
stores or loads to that memory.
See also:
https://gcc.gnu.org/onlinedocs/gcc-4.7.2/gcc/Extended-Asm.html
http://stackoverflow.com/questions/14449141/the-difference-between-asm-asm-volatile-and-clobbering-memory
Diffstat (limited to 'src/syscall.rs')
| -rw-r--r-- | src/syscall.rs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/syscall.rs b/src/syscall.rs index 681f73f..01d87fd 100644 --- a/src/syscall.rs +++ b/src/syscall.rs @@ -1,4 +1,4 @@ -/// SYSCALL invokes an OS system-call handler at privilege level 0. +//! Invokes an OS system-call handler at privilege level 0. /// /// It does so by loading RIP from the IA32_LSTAR MSR (after saving the address of the instruction following SYSCALL into RCX). /// |