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Switch vmmouse global_asm block back to inline asm

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There seems to be a bug somewhere in the global_asm block which causes a
SIGSEGV when making unrelated code changes to ps2d. Using an inline asm
block is easier to follow and less error prone around following the
calling convention.
This commit is contained in:
bjorn3
2024-01-12 18:28:17 +01:00
parent 9422366782
commit bc7469f7cd
1 changed files with 20 additions and 39 deletions
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ps2d/src/vm.rs
+20 -39
View File
@@ -4,7 +4,7 @@
// As well as the Linux implementation here:
// http://elixir.free-electrons.com/linux/v4.1/source/drivers/input/mouse/vmmouse.c
use core::arch::global_asm;
use core::arch::asm;
const MAGIC: u32 = 0x564D5868;
const PORT: u16 = 0x5658;
@@ -27,49 +27,30 @@ pub const LEFT_BUTTON: u32 = 0x20;
pub const RIGHT_BUTTON: u32 = 0x10;
pub const MIDDLE_BUTTON: u32 = 0x08;
#[cfg(target_arch = "x86_64")]
global_asm!("
.globl cmd_inner
cmd_inner:
mov r8, rdi
// 2nd argument `cmd` as per sysv64.
mov ecx, esi
// 3rd argument `arg` as per sysv64.
mov ebx, edx
mov eax, {MAGIC}
mov dx, {PORT}
in eax, dx
xchg rdi, r8
mov DWORD PTR [rdi + 0x00], eax
mov DWORD PTR [rdi + 0x04], ebx
mov DWORD PTR [rdi + 0x08], ecx
mov DWORD PTR [rdi + 0x0C], edx
mov DWORD PTR [rdi + 0x10], esi
mov DWORD PTR [rdi + 0x14], r8d
ret
",
MAGIC = const MAGIC,
PORT = const PORT,
);
#[cfg(target_arch = "x86_64")]
pub unsafe fn cmd(cmd: u32, arg: u32) -> (u32, u32, u32, u32, u32, u32) {
extern "sysv64" {
fn cmd_inner(array_ptr: *mut u32, cmd: u32, arg: u32);
}
let a: u32;
let b: u32;
let c: u32;
let d: u32;
let si: u32;
let di: u32;
let mut array = [0_u32; 6];
// ebx can't be used as input or output constraint in rust as LLVM reserves it.
// Use xchg to pass it through r9 instead while restoring the original value in
// rbx when leaving the inline asm block.
asm!(
"xchg r9, rbx; in eax, dx; xchg r9, rbx",
inout("eax") MAGIC => a,
inout("r9") arg => b,
inout("ecx") cmd => c,
inout("edx") PORT as u32 => d,
out("esi") si,
out("edi") di,
);
cmd_inner(array.as_mut_ptr(), cmd, arg);
(a, b, c, d, si, di)
let [a, b, c, d, e, f] = array;
(a, b, c, d, e, f)
}
//TODO: is it possible to enable this on non-x86_64?