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sys/arm64/arm64/exception.S

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/* /*
* This is limited to 28 instructions as it's placed in the exception vector * This is limited to 28 instructions as it's placed in the exception vector
* slot that is 32 instructions long. We need one for the branch, and three * slot that is 32 instructions long. We need one for the branch, and three
* for the prologue. * for the prologue.
*/ */
.macro save_registers_head el .macro save_registers_head el
.if \el == 1 .if \el == 1
mov x18, sp
stp x0, x1, [sp, #-(TF_SIZE - TF_X + 128)]! stp x0, x1, [sp, #-(TF_SIZE - TF_X + 128)]!
.else .else
stp x0, x1, [sp, #-(TF_SIZE - TF_X)]! stp x0, x1, [sp, #-(TF_SIZE - TF_X)]!
.endif .endif
stp x2, x3, [sp, #(2 * 8)] stp x2, x3, [sp, #(2 * 8)]
stp x4, x5, [sp, #(4 * 8)] stp x4, x5, [sp, #(4 * 8)]
stp x6, x7, [sp, #(6 * 8)] stp x6, x7, [sp, #(6 * 8)]
stp x8, x9, [sp, #(8 * 8)] stp x8, x9, [sp, #(8 * 8)]
stp x10, x11, [sp, #(10 * 8)] stp x10, x11, [sp, #(10 * 8)]
stp x12, x13, [sp, #(12 * 8)] stp x12, x13, [sp, #(12 * 8)]
stp x14, x15, [sp, #(14 * 8)] stp x14, x15, [sp, #(14 * 8)]
stp x16, x17, [sp, #(16 * 8)] stp x16, x17, [sp, #(16 * 8)]
stp x18, x19, [sp, #(18 * 8)] stp x18, x19, [sp, #(18 * 8)]
stp x20, x21, [sp, #(20 * 8)] stp x20, x21, [sp, #(20 * 8)]
stp x22, x23, [sp, #(22 * 8)] stp x22, x23, [sp, #(22 * 8)]
stp x24, x25, [sp, #(24 * 8)] stp x24, x25, [sp, #(24 * 8)]
stp x26, x27, [sp, #(26 * 8)] stp x26, x27, [sp, #(26 * 8)]
stp x28, x29, [sp, #(28 * 8)] stp x28, x29, [sp, #(28 * 8)]
.if \el == 0 .if \el == 1
add x18, sp, #(TF_SIZE - TF_X + 128)
andrewUnsubmitted
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Not a sub with a positive value?

andrew: Not a `sub` with a positive value?
jhbAuthorUnsubmitted
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Hmm, I could do that if that is cleaner. Probably does read better in fact.

jhb: Hmm, I could do that if that is cleaner. Probably does read better in fact.
jhbAuthorUnsubmitted
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One thing to keep in mind is that TF_X (48) - TF_SIZE (288) is actually negative, so this actually ends up being:

add x18, sp, #368

(And logically, sp should be moving down the stack so getting back to the original value should be an add.)

jhb: One thing to keep in mind is that TF_X (48) - TF_SIZE (288) is actually negative, so this…
defUnsubmitted
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I like having add here to indicate that it "reverts" the stack allocation and that you used "-(the original value)" to easily correlate that with the stack allocation at the beginning of this macro.

def: I like having `add` here to indicate that it "reverts" the stack allocation and that you used "…
andrewUnsubmitted
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I think the EL1 stp would be clearer if it used #-(TF_SIZE - TF_X + 128) (and similar for the EL0 case) & this to the positive version.

A more intrusive change would be to reorder struct trapframe so tf_x is first & we could just set sp to the base of the trapframe. This would need more testing as we reuse it in vmm.ko.

andrew: I think the EL1 `stp` would be clearer if it used `#-(TF_SIZE - TF_X + 128)` (and similar for…
jhbAuthorUnsubmitted
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Changing trapframe is a bit fraught as kgdb hardcodes that knowledge. I would be fine with fixing the arguments to stp to be clearer (and in fact I would prefer that quite a bit). I can add that as a commit before this and post a new review for that.

jhb: Changing trapframe is a bit fraught as kgdb hardcodes that knowledge. I would be fine with…
.else
mrs x18, sp_el0 mrs x18, sp_el0
.endif .endif
mrs x10, elr_el1 mrs x10, elr_el1
mrs x11, spsr_el1 mrs x11, spsr_el1
mrs x12, esr_el1 mrs x12, esr_el1
mrs x13, far_el1 mrs x13, far_el1
stp x18, lr, [sp, #(TF_SP - TF_X)]! stp x18, lr, [sp, #(TF_SP - TF_X)]!
stp x10, x11, [sp, #(TF_ELR)] stp x10, x11, [sp, #(TF_ELR)]
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