aarch32-rt 0.4.0

Run-time support for Arm AArch32
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81

//! Data and Prefetch Abort handlers for Armv4 to Armv6

core::arch::global_asm!(
    r#"
    // Work around https://github.com/rust-lang/rust/issues/127269
    .fpu vfp2

    // Called from the vector table when we have an undefined exception.
    // Saves state and calls a C-compatible handler like
    // `extern "C" fn _data_abort_handler(addr: usize);`
    .pushsection .text._asm_default_data_abort_handler
    .arm
    .global _asm_default_data_abort_handler
    .type _asm_default_data_abort_handler, %function
    _asm_default_data_abort_handler:
        sub     lr, lr, #8                // Make sure we jump back to the right place
        push    {{ r12 }}                 // Push preserved register R12 (1)
        mrs     r12, spsr                 // Grab SPSR (2)
        push    {{ r12 }}                 // Push SPSR value (3)
        and     r12, sp, 7                // Align SP down to eight byte boundary using R12 
        sub     sp, r12                   // SP now aligned - only push 64-bit values from here (4)
        push    {{ r0-r4, r12 }}          // Push preserved registers and alignment amount (R4 is just padding) (5)
    "#,
    crate::fpu_context!("save"),
    r#"
        mov     r0, lr                    // Pass the faulting instruction address to the handler.
        bl      _data_abort_handler       // Call C handler
        mov     lr, r0                    // If we get back here, assume they returned a new LR in r0
    "#,
    crate::fpu_context!("restore"),
    r#"
        pop     {{ r0-r4, r12 }}          // Pop preserved registers, dummy value, and alignment amount to undo (5)
        add     sp, r12                   // Restore SP alignment using R12 to undo (4)
        pop     {{ r12 }}                 // Pop saved SPSR value to undo (3)
        msr     spsr, r12                 // Restore SPSR using R12 to undo (2)
        pop     {{ r12 }}                 // Pop R12 to undo (1)
        movs    pc, lr                    // Return from exception
    .size _asm_default_data_abort_handler, . - _asm_default_data_abort_handler
    .popsection
    "#
);

core::arch::global_asm!(
    r#"
    // Work around https://github.com/rust-lang/rust/issues/127269
    .fpu vfp2

    // Called from the vector table when we have a prefetch abort.
    // Saves state and calls a C-compatible handler like
    // `extern "C" fn _prefetch_abort_handler(addr: usize);`
    .pushsection .text._asm_default_prefetch_abort_handler
    .arm
    .global _asm_default_prefetch_abort_handler
    .type _asm_default_prefetch_abort_handler, %function
    _asm_default_prefetch_abort_handler:
        sub     lr, lr, #4                // Make sure we jump back to the right place
        push    {{ r12 }}                 // Push preserved register R12 (1)
        mrs     r12, spsr                 // Grab SPSR (2)
        push    {{ r12 }}                 // Push SPSR value (3)
        and     r12, sp, 7                // Align SP down to eight byte boundary using R12
        sub     sp, r12                   // SP now aligned - only push 64-bit values from here (4)
        push    {{ r0-r4, r12 }}          // Push preserved registers and alignment amount (R4 is just padding) (5)
    "#,
    crate::fpu_context!("save"),
    r#"
        mov     r0, lr                    // Pass the faulting instruction address to the handler.
        bl      _prefetch_abort_handler   // Call C handler
        mov     lr, r0                    // If we get back here, assume they returned a new LR in r0
    "#,
    crate::fpu_context!("restore"),
    r#"
        pop     {{ r0-r4, r12 }}          // Pop preserved registers, dummy value, and alignment amount to undo (5)
        add     sp, r12                   // Restore SP alignment using R12 to undo (4)
        pop     {{ r12 }}                 // Grab saved SPSR to undo (3)
        msr     spsr, r12                 // Restore SPSR using R12 to undo (2)
        pop     {{ r12 }}                 // Pop R12 to undo (1)
        movs    pc, lr                    // Return from exception
    .size _asm_default_prefetch_abort_handler, . - _asm_default_prefetch_abort_handler
    .popsection
    "#,
);