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Replace all remaining llvm_asm! with asm! (#694)
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Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
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@tomaka @mergify
tomaka and mergify[bot] authored Jan 1, 2021
1 parent 4823a89 commit dd3b7f1
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Showing 7 changed files with 56 additions and 53 deletions.
82 changes: 43 additions & 39 deletions kernel/standalone/src/arch/arm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -61,31 +61,37 @@ macro_rules! __gen_boot {
// (ARMv7-A and ARMv7-R edition).
//
// This is specific to ARMv7-A and ARMv7-R, hence the compile_error! above.
llvm_asm!(
r#"
mrc p15, 0, r5, c0, c0, 5
and r5, r5, #3
cmp r5, #0
bne halt
"#::::"volatile");
asm!(
"
mrc p15, 0, r5, c0, c0, 5
and r5, r5, #3
cmp r5, #0
bne {}
",
sym halt,
out("r3") _, out("r5") _,
options(nomem, nostack, preserves_flags)
);

// Only one CPU reaches here.

// Zero the BSS segment.
// TODO: we pray here that the compiler doesn't use the stack
let mut ptr = &mut __bss_start as *mut u8;
while ptr < &mut __bss_end as *mut u8 {
// TODO: that's illegal ; naked functions must only contain an asm! block (for good reasons)
let mut ptr = &mut $bss_start as *mut u8;
while ptr < &mut $bss_end as *mut u8 {
ptr.write_volatile(0);
ptr = ptr.add(1);
}

// Set up the stack.
llvm_asm!(r#"
.comm stack, 0x400000, 8
ldr sp, =stack+0x400000"#:::"memory":"volatile");

llvm_asm!(r#"b cpu_enter"#:::"volatile");
core::hint::unreachable_unchecked()
// Set up the stack and jump to the entry point.
asm!("
.comm stack, 0x400000, 8
ldr sp, =stack+0x400000
b {}
",
sym cpu_enter,
options(noreturn)
)
}

/// This is the main entry point of the kernel for ARM 64bits architectures.
Expand All @@ -94,37 +100,37 @@ macro_rules! __gen_boot {
#[naked]
unsafe extern "C" fn entry_point_arm64() -> ! {
// TODO: review this
llvm_asm!(r#"
asm!(
"
mrs x6, MPIDR_EL1
and x6, x6, #0x3
cbz x6, L0
b halt
b {}
L0: nop
"#::::"volatile");
",
sym halt,
out("x6") _,
options(nomem, nostack)
);

// Only one CPU reaches here.

// Zero the BSS segment.
// TODO: we pray here that the compiler doesn't use the stack
let mut ptr = &mut __bss_start as *mut u8;
while ptr < &mut __bss_end as *mut u8 {
// TODO: that's illegal ; naked functions must only contain an asm! block (for good reasons)
let mut ptr = &mut $bss_start as *mut u8;
while ptr < &mut $bss_end as *mut u8 {
ptr.write_volatile(0);
ptr = ptr.add(1);
}

// Set up the stack.
llvm_asm!(r#"
// Set up the stack and jump to `cpu_enter`.
asm!(
"
.comm stack, 0x400000, 8
ldr x5, =stack+0x400000; mov sp, x5"#:::"memory":"volatile");

llvm_asm!(r#"b cpu_enter"#:::"volatile");
core::hint::unreachable_unchecked()
}

// TODO: remove in favour of the values passed by user of the macro
extern "C" {
static mut __bss_start: u8;
static mut __bss_end: u8;
ldr x5, =stack+0x400000
mov sp, x5
b {}
", sym cpu_enter, options(noreturn))
}

/// Main Rust entry point.
Expand All @@ -149,13 +155,11 @@ macro_rules! __gen_boot {
$crate::arch::arm::executor::block_on($entry(platform))
}

// TODO: remove no_mangle after transitionning from `llvm_asm!` to `asm!` above
#[no_mangle]
#[naked]
fn halt() -> ! {
unsafe {
loop {
llvm_asm!(r#"wfe"#);
asm!("wfe", options(nomem, nostack, preserves_flags));
}
}
}
Expand Down Expand Up @@ -270,7 +274,7 @@ pub fn init_uart() -> UartInfo {
fn delay(count: i32) {
unsafe {
for _ in 0..count {
llvm_asm!("nop" ::: "volatile");
asm!("nop", options(nostack, nomem, preserves_flags));
}
}
}
4 changes: 2 additions & 2 deletions kernel/standalone/src/arch/arm/executor.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,7 @@ pub fn block_on<R>(future: impl Future<Output = R>) -> R {
// Thanks to this, if an event happens between the moment when we check the value of
// `local_waken.woken_up` and the moment when we call `wfe`, then the `wfe`
// instruction will immediately return and we will check the value again.
unsafe { llvm_asm!("wfe" :::: "volatile") }
unsafe { asm!("wfe", options(nomem, nostack, preserves_flags)) }
}
}
}
Expand All @@ -72,7 +72,7 @@ impl ArcWake for LocalWake {
// Wakes up all the CPUs that called `wfe`.
// Note that this wakes up *all* CPUs, but the ARM architecture doesn't provide any
// way to target a single CPU for wake-up.
llvm_asm!("dsb sy ; sev" :::: "volatile")
asm!("dsb sy ; sev", options(nomem, nostack, preserves_flags))
}
}
}
2 changes: 1 addition & 1 deletion kernel/standalone/src/arch/arm/log.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,7 @@ fn panic(panic_info: &core::panic::PanicInfo) -> ! {
// Freeze forever.
unsafe {
loop {
llvm_asm!(r#"wfe"#);
asm!("wfe", options(nomem, nostack, preserves_flags));
}
}
}
2 changes: 1 addition & 1 deletion kernel/standalone/src/arch/arm/time_aarch64.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,7 @@ impl TimeControl {
unsafe {
// TODO: stub
let val: u64;
llvm_asm!("mrs $0, CNTPCT_EL0": "=r"(val) ::: "volatile");
asm!("mrs {}, CNTPCT_EL0", out(reg) val, options(nostack, nomem, preserves_flags));
u128::from(val)
}
}
Expand Down
10 changes: 5 additions & 5 deletions kernel/standalone/src/arch/arm/time_arm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -98,7 +98,7 @@ impl TimeControl {
pub unsafe fn init() -> Arc<TimeControl> {
// Initialize the physical counter frequency.
// TODO: I think this is a global setting, but make sure it's the case?
llvm_asm!("mcr p15, 0, $0, c14, c0, 0"::"r"(CNTFRQ)::"volatile");
asm!("mcr p15, 0, {}, c14, c0, 0", in(reg) CNTFRQ, options(nomem, nostack, preserves_flags));

// TODO: this code doesn't work, as we have to register some IRQ handler or something to
// check the state of the timers and fire the wakers
Expand Down Expand Up @@ -229,7 +229,7 @@ fn physical_counter() -> u64 {
unsafe {
let lo: u32;
let hi: u32;
llvm_asm!("mrrc p15, 0, $0, $1, c14": "=r"(lo), "=r"(hi) ::: "volatile");
asm!("mrrc p15, 0, {}, {}, c14", out(reg) lo, out(reg) hi, options(nostack, nomem, preserves_flags));
u64::from(hi) << 32 | u64::from(lo)
}
}
Expand All @@ -243,21 +243,21 @@ fn update_hardware(timers: &mut Vec<Timer>) {
// If there's no active timer, disable the timer firing by updating the `CNTP_CTL`
// register.
if timers.is_empty() {
llvm_asm!("mcr p15, 0, $0, c14, c2, 1" :: "r"(0));
asm!("mcr p15, 0, {}, c14, c2, 1", in(reg) 0);
return;
}

// Make sure that the timer is enabled by updating the `CNTP_CTL` register.
// TODO: don't do this every single time
llvm_asm!("mcr p15, 0, $0, c14, c2, 1" :: "r"(0b01));
asm!("mcr p15, 0, {}, c14, c2, 1", in(reg) 0b01);

// Write the `CNTP_CVAL` register with the value to compare with.
// The timer will fire when the physical counter (`CNTPCT`) reaches the given value.
{
let cmp_value = timers.get(0).unwrap().counter_value;
let lo = u32::try_from(cmp_value & 0xffffffff).unwrap();
let hi = u32::try_from(cmp_value >> 32).unwrap();
llvm_asm!("mcrr p15, 2, $0, $1, c14" :: "r"(lo), "r"(hi));
asm!("mcrr p15, 2, {}, {}, c14", in(reg) lo, in(reg) hi);
}
}
}
8 changes: 4 additions & 4 deletions kernel/standalone/src/arch/riscv.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -192,9 +192,9 @@ impl PlatformSpecificImpl {
let hi1: u32;
let hi2: u32;

// Note that we put all three instructions in the same `llvm_asm!`, to prevent the
// compiler from reordering them.
llvm_asm!("rdtimeh $0 ; rdtime $1 ; rdtimeh $2" : "=r"(hi1), "=r"(lo), "=r"(hi2));
// Note that we put all three instructions in the same `asm!`, to prevent the
// compiler from possibly reordering them.
asm!("rdtimeh {} ; rdtime {} ; rdtimeh {}", out(reg) hi1, out(reg) lo, out(reg) hi2);

if hi1 == hi2 {
break (u64::from(hi1) << 32) | u64::from(lo);
Expand All @@ -211,7 +211,7 @@ impl PlatformSpecificImpl {
// TODO: this is only supported in the "I" version of RISC-V; check that
unsafe {
let val: u64;
llvm_asm!("rdtime $0" : "=r"(val));
asm!("rdtime {}", out(reg) reg);
u128::from(val)
}
}
Expand Down
1 change: 0 additions & 1 deletion kernel/standalone/src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,6 @@
#![feature(allocator_api)] // TODO: https://github.com/rust-lang/rust/issues/32838
#![feature(alloc_error_handler)] // TODO: https://github.com/rust-lang/rust/issues/66741
#![feature(asm)] // TODO: https://github.com/rust-lang/rust/issues/72016
#![feature(llvm_asm)] // TODO: replace all occurrences of `llvm_asm!` with `asm!`
#![feature(naked_functions)] // TODO: https://github.com/rust-lang/rust/issues/32408
#![cfg_attr(target_arch = "x86_64", feature(abi_x86_interrupt))] // TODO: https://github.com/rust-lang/rust/issues/40180

Expand Down

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