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kern: swap tpidr_el1/cntv_cval_el0 as scratch vs exception stack

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This commit is contained in:
Michael Scire
2021-04-07 08:36:03 -07:00
committed by SciresM
parent 2f930c2d5f
commit c216f92a91
7 changed files with 34 additions and 28 deletions
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36
mesosphere/kernel/source/arch/arm64/kern_exception_handlers_asm.s
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@@ -281,8 +281,8 @@ _ZN3ams4kern4arch5arm6430EL0SynchronousExceptionHandlerEv:
.global _ZN3ams4kern4arch5arm6430EL1SynchronousExceptionHandlerEv
.type _ZN3ams4kern4arch5arm6430EL1SynchronousExceptionHandlerEv, %function
_ZN3ams4kern4arch5arm6430EL1SynchronousExceptionHandlerEv:
/* Nintendo uses the "unused" virtual timer compare value as a scratch register. */
msr cntv_cval_el0, x0
/* Nintendo uses tpidr_el1 as a scratch register. */
msr tpidr_el1, x0
/* Get and parse the exception syndrome register. */
mrs x0, esr_el1
@@ -297,18 +297,21 @@ _ZN3ams4kern4arch5arm6430EL1SynchronousExceptionHandlerEv:
b.eq 5f
1: /* The exception is not a data abort or instruction abort caused by a TLB conflict. */
/* Load the exception stack top from tpidr_el1. */
mrs x0, tpidr_el1
/* Load the exception stack top from otherwise "unused" virtual timer compare value. */
mrs x0, cntv_cval_el0
/* Setup the stack for a generic exception handle */
lsl x0, x0, #8
asr x0, x0, #8
sub x0, x0, #0x20
str x1, [x0, #16]
str x1, [x0, #8]
mov x1, sp
str x1, [x0]
mov sp, x0
ldr x1, [x0, #16]
mrs x0, cntv_cval_el0
ldr x1, [x0, #8]
mrs x0, tpidr_el1
str x0, [sp, #8]
str x1, [sp, #16]
/* Check again if this is a data abort from EL1. */
mrs x0, esr_el1
@@ -406,7 +409,7 @@ _ZN3ams4kern4arch5arm6430EL1SynchronousExceptionHandlerEv:
isb
/* Restore x0 from scratch. */
mrs x0, cntv_cval_el0
mrs x0, tpidr_el1
/* Return from the exception. */
eret
@@ -474,21 +477,22 @@ _ZN3ams4kern4arch5arm6425FpuAccessExceptionHandlerEv:
.global _ZN3ams4kern4arch5arm6421EL1SystemErrorHandlerEv
.type _ZN3ams4kern4arch5arm6421EL1SystemErrorHandlerEv, %function
_ZN3ams4kern4arch5arm6421EL1SystemErrorHandlerEv:
/* Nintendo uses the "unused" virtual timer compare value as a scratch register. */
msr cntv_cval_el0, x0
/* Nintendo uses tpidr_el1 as a scratch register. */
msr tpidr_el1, x0
/* Load the exception stack top from tpidr_el1. */
mrs x0, tpidr_el1
/* Load the exception stack top from otherwise "unused" virtual timer compare value. */
mrs x0, cntv_cval_el0
/* Setup the stack for a generic exception handle */
lsl x0, x0, #8
asr x0, x0, #8
sub x0, x0, #0x20
str x1, [x0, #16]
str x1, [x0, #8]
mov x1, sp
str x1, [x0]
mov sp, x0
ldr x1, [x0, #16]
mrs x0, cntv_cval_el0
str x0, [sp, #8]
ldr x1, [x0, #8]
mrs x0, tpidr_el1
/* Create a KExceptionContext to pass to HandleException. */
sub sp, sp, #0x120