From bd599343505d202dc3d8226ca80d5f1af0247bf2 Mon Sep 17 00:00:00 2001
From: Liam <byteslice@airmail.cc>
Date: Thu, 30 Nov 2023 14:05:02 -0500
Subject: nce: implement instruction emulation for misaligned memory accesses

---
 src/core/arm/nce/arm_nce.s | 60 ++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 53 insertions(+), 7 deletions(-)

(limited to 'src/core/arm/nce/arm_nce.s')

diff --git a/src/core/arm/nce/arm_nce.s b/src/core/arm/nce/arm_nce.s
index 4aeda4740..c68c05949 100644
--- a/src/core/arm/nce/arm_nce.s
+++ b/src/core/arm/nce/arm_nce.s
@@ -130,11 +130,11 @@ _ZN4Core6ArmNce29BreakFromRunCodeSignalHandlerEiPvS1_:
     ret
 
 
-/* static void Core::ArmNce::GuestFaultSignalHandler(int sig, void* info, void* raw_context) */
-.section    .text._ZN4Core6ArmNce23GuestFaultSignalHandlerEiPvS1_, "ax", %progbits
-.global     _ZN4Core6ArmNce23GuestFaultSignalHandlerEiPvS1_
-.type       _ZN4Core6ArmNce23GuestFaultSignalHandlerEiPvS1_, %function
-_ZN4Core6ArmNce23GuestFaultSignalHandlerEiPvS1_:
+/* static void Core::ArmNce::GuestAlignmentFaultSignalHandler(int sig, void* info, void* raw_context) */
+.section    .text._ZN4Core6ArmNce32GuestAlignmentFaultSignalHandlerEiPvS1_, "ax", %progbits
+.global     _ZN4Core6ArmNce32GuestAlignmentFaultSignalHandlerEiPvS1_
+.type       _ZN4Core6ArmNce32GuestAlignmentFaultSignalHandlerEiPvS1_, %function
+_ZN4Core6ArmNce32GuestAlignmentFaultSignalHandlerEiPvS1_:
     /* Check to see if we have the correct TLS magic. */
     mrs     x8, tpidr_el0
     ldr     w9, [x8, #(TpidrEl0TlsMagic)]
@@ -146,7 +146,7 @@ _ZN4Core6ArmNce23GuestFaultSignalHandlerEiPvS1_:
 
     /* Incorrect TLS magic, so this is a host fault. */
     /* Tail call the handler. */
-    b       _ZN4Core6ArmNce15HandleHostFaultEiPvS1_
+    b       _ZN4Core6ArmNce24HandleHostAlignmentFaultEiPvS1_
 
 1:
     /* Correct TLS magic, so this is a guest fault. */
@@ -163,7 +163,53 @@ _ZN4Core6ArmNce23GuestFaultSignalHandlerEiPvS1_:
     msr     tpidr_el0, x3
 
     /* Call the handler. */
-    bl       _ZN4Core6ArmNce16HandleGuestFaultEPNS_12GuestContextEPvS3_
+    bl       _ZN4Core6ArmNce25HandleGuestAlignmentFaultEPNS_12GuestContextEPvS3_
+
+    /* If the handler returned false, we want to preserve the host tpidr_el0. */
+    cbz     x0, 2f
+
+    /* Otherwise, restore guest tpidr_el0. */
+    msr     tpidr_el0, x19
+
+2:
+    ldr     x19, [sp, #0x10]
+    ldp     x29, x30, [sp], #0x20
+    ret
+
+/* static void Core::ArmNce::GuestAccessFaultSignalHandler(int sig, void* info, void* raw_context) */
+.section    .text._ZN4Core6ArmNce29GuestAccessFaultSignalHandlerEiPvS1_, "ax", %progbits
+.global     _ZN4Core6ArmNce29GuestAccessFaultSignalHandlerEiPvS1_
+.type       _ZN4Core6ArmNce29GuestAccessFaultSignalHandlerEiPvS1_, %function
+_ZN4Core6ArmNce29GuestAccessFaultSignalHandlerEiPvS1_:
+    /* Check to see if we have the correct TLS magic. */
+    mrs     x8, tpidr_el0
+    ldr     w9, [x8, #(TpidrEl0TlsMagic)]
+
+    LOAD_IMMEDIATE_32(w10, TlsMagic)
+
+    cmp     w9, w10
+    b.eq    1f
+
+    /* Incorrect TLS magic, so this is a host fault. */
+    /* Tail call the handler. */
+    b       _ZN4Core6ArmNce21HandleHostAccessFaultEiPvS1_
+
+1:
+    /* Correct TLS magic, so this is a guest fault. */
+    stp     x29, x30, [sp, #-0x20]!
+    str     x19, [sp, #0x10]
+    mov     x29, sp
+
+    /* Save the old tpidr_el0. */
+    mov     x19, x8
+
+    /* Restore host tpidr_el0. */
+    ldr     x0, [x8, #(TpidrEl0NativeContext)]
+    ldr     x3, [x0, #(GuestContextHostContext + HostContextTpidrEl0)]
+    msr     tpidr_el0, x3
+
+    /* Call the handler. */
+    bl       _ZN4Core6ArmNce22HandleGuestAccessFaultEPNS_12GuestContextEPvS3_
 
     /* If the handler returned false, we want to preserve the host tpidr_el0. */
     cbz     x0, 2f
-- 
cgit v1.2.3