Use the sym operator for inline assembly (#5459)
* Use the `sym` operator for inline assembly Avoids extra `#[no_mangle]` functions and undue symbols being exposed from Wasmtime. This is a newly stabilized feature in Rust 1.66.0. I've also added a `rust-version` entry to the `wasmtime` crate to try to head off possible reports in the future about odd error messages or usage of unstable features if the rustc version is too old. * Fix a s390x warning * Add `rust-version` annotation to Wasmtime crate As the other main entrypoint for embedders.
This commit is contained in:
Alex Crichton
@@ -18,6 +18,7 @@
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// `DW_CFA_AARCH64_negate_ra_state` DWARF operation (aliased with the
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// `.cfi_window_save` assembler directive) informs an unwinder about this
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use super::wasmtime_fiber_start;
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use wasmtime_asm_macros::asm_func;
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cfg_if::cfg_if! {
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@@ -25,8 +26,8 @@ cfg_if::cfg_if! {
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macro_rules! paci1716 { () => ("pacib1716\n"); }
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macro_rules! pacisp { () => ("pacibsp\n"); }
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macro_rules! autisp { () => ("autibsp\n"); }
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macro_rules! sym_adrp { ($s:tt) => (concat!("_", $s, "@PAGE")); }
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macro_rules! sym_add { ($s:tt) => (concat!("_", $s, "@PAGEOFF")); }
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macro_rules! sym_adrp { ($s:tt) => (concat!($s, "@PAGE")); }
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macro_rules! sym_add { ($s:tt) => (concat!($s, "@PAGEOFF")); }
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} else {
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macro_rules! paci1716 { () => ("pacia1716\n"); }
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macro_rules! pacisp { () => ("paciasp\n"); }
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@@ -39,52 +40,54 @@ cfg_if::cfg_if! {
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// fn(top_of_stack(%x0): *mut u8)
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asm_func!(
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"wasmtime_fiber_switch",
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"
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.cfi_startproc
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",
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pacisp!(),
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"
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.cfi_window_save
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// Save all callee-saved registers on the stack since we're
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// assuming they're clobbered as a result of the stack switch.
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stp x29, x30, [sp, -16]!
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stp x20, x19, [sp, -16]!
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stp x22, x21, [sp, -16]!
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stp x24, x23, [sp, -16]!
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stp x26, x25, [sp, -16]!
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stp x28, x27, [sp, -16]!
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stp d9, d8, [sp, -16]!
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stp d11, d10, [sp, -16]!
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stp d13, d12, [sp, -16]!
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stp d15, d14, [sp, -16]!
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concat!(
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"
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.cfi_startproc
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",
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pacisp!(),
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"
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.cfi_window_save
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// Save all callee-saved registers on the stack since we're
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// assuming they're clobbered as a result of the stack switch.
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stp x29, x30, [sp, -16]!
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stp x20, x19, [sp, -16]!
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stp x22, x21, [sp, -16]!
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stp x24, x23, [sp, -16]!
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stp x26, x25, [sp, -16]!
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stp x28, x27, [sp, -16]!
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stp d9, d8, [sp, -16]!
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stp d11, d10, [sp, -16]!
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stp d13, d12, [sp, -16]!
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stp d15, d14, [sp, -16]!
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// Load our previously saved stack pointer to resume to, and save
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// off our current stack pointer on where to come back to
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// eventually.
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ldr x8, [x0, -0x10]
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mov x9, sp
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str x9, [x0, -0x10]
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// Load our previously saved stack pointer to resume to, and save
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// off our current stack pointer on where to come back to
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// eventually.
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ldr x8, [x0, -0x10]
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mov x9, sp
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str x9, [x0, -0x10]
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// Switch to the new stack and restore all our callee-saved
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// registers after the switch and return to our new stack.
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mov sp, x8
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ldp d15, d14, [sp], 16
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ldp d13, d12, [sp], 16
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ldp d11, d10, [sp], 16
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ldp d9, d8, [sp], 16
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ldp x28, x27, [sp], 16
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ldp x26, x25, [sp], 16
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ldp x24, x23, [sp], 16
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ldp x22, x21, [sp], 16
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ldp x20, x19, [sp], 16
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ldp x29, x30, [sp], 16
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",
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autisp!(),
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"
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.cfi_window_save
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ret
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.cfi_endproc
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",
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// Switch to the new stack and restore all our callee-saved
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// registers after the switch and return to our new stack.
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mov sp, x8
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ldp d15, d14, [sp], 16
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ldp d13, d12, [sp], 16
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ldp d11, d10, [sp], 16
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ldp d9, d8, [sp], 16
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ldp x28, x27, [sp], 16
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ldp x26, x25, [sp], 16
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ldp x24, x23, [sp], 16
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ldp x22, x21, [sp], 16
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ldp x20, x19, [sp], 16
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ldp x29, x30, [sp], 16
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",
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autisp!(),
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"
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.cfi_window_save
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ret
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.cfi_endproc
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",
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),
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);
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// fn(
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@@ -112,26 +115,29 @@ asm_func!(
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#[rustfmt::skip]
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asm_func!(
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"wasmtime_fiber_init",
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"
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.cfi_startproc
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hint #34 // bti c
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sub x16, x0, #16
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adrp x17, ", sym_adrp!("wasmtime_fiber_start"), "
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add x17, x17, ", sym_add!("wasmtime_fiber_start"), "
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",
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paci1716!(),
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"
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str x17, [x16, -0x8] // x17 => lr
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str x0, [x16, -0x18] // x0 => x19
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stp x2, x1, [x0, -0x38] // x1 => x20, x2 => x21
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concat!(
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"
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.cfi_startproc
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hint #34 // bti c
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sub x16, x0, #16
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adrp x17, ", sym_adrp!("{fiber}"), "
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add x17, x17, ", sym_add!("{fiber}"), "
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",
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paci1716!(),
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"
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str x17, [x16, -0x8] // x17 => lr
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str x0, [x16, -0x18] // x0 => x19
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stp x2, x1, [x0, -0x38] // x1 => x20, x2 => x21
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// `wasmtime_fiber_switch` has an 0xa0 byte stack, and we add 0x10 more for
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// the original reserved 16 bytes.
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add x8, x0, -0xb0
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str x8, [x0, -0x10]
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ret
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.cfi_endproc
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",
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// `wasmtime_fiber_switch` has an 0xa0 byte stack, and we add 0x10 more for
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// the original reserved 16 bytes.
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add x8, x0, -0xb0
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str x8, [x0, -0x10]
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ret
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.cfi_endproc
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",
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),
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fiber = sym wasmtime_fiber_start,
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);
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// See the x86_64 file for more commentary on what these CFI directives are
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@@ -92,17 +92,18 @@ asm_func!(
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asm_func!(
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"wasmtime_fiber_init",
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"
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lla t0,wasmtime_fiber_start
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lla t0,{}
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sd t0,-0x18(a0) // ra,first should be wasmtime_fiber_start.
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sd a0,-0x20(a0) // fp pointer.
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sd a1,-0x28(a0) // entry_point will load to s1.
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sd a1,-0x28(a0) // entry_point will load to s1.
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sd a2,-0x30(a0) // entry_arg0 will load to s2.
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//
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//
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addi t0,a0,-0xe0
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sd t0,-0x10(a0)
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ret
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",
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sym super::wasmtime_fiber_start,
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);
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asm_func!(
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@@ -118,8 +119,8 @@ asm_func!(
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0x06, /* DW_OP_deref */ \
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0x08, 0xd0 , /* DW_OP_const1u 0xc8 */ \
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0x22 /* DW_OP_plus */
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.cfi_rel_offset ra,-0x8
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.cfi_rel_offset fp,-0x10
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.cfi_rel_offset s1,-0x18
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@@ -5,7 +5,7 @@
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// all the other bits. Documentation tries to reference various bits here and
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// there but try to make sure to read over everything before tweaking things!
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use wasmtime_asm_macros::{asm_func, asm_sym};
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use wasmtime_asm_macros::asm_func;
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// fn(top_of_stack(rdi): *mut u8)
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asm_func!(
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@@ -58,7 +58,7 @@ asm_func!(
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//
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// The first 16 bytes of stack are reserved for metadata, so we start
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// storing values beneath that.
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lea rax, ", asm_sym!("wasmtime_fiber_start"), "[rip]
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lea rax, {start}[rip]
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mov -0x18[rdi], rax
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mov -0x20[rdi], rdi // loaded into rbp during switch
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mov -0x28[rdi], rsi // loaded into rbx during switch
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@@ -73,6 +73,7 @@ asm_func!(
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mov -0x10[rdi], rax
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ret
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",
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start = sym super::wasmtime_fiber_start,
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);
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// This is a pretty special function that has no real signature. Its use is to
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