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| 1 /* |
| 2 * Copyright 2012 The Native Client Authors. All rights reserved. |
| 3 * Use of this source code is governed by a BSD-style license that can |
| 4 * be found in the LICENSE file. |
| 5 */ |
| 6 |
| 7 #include "native_client/src/trusted/service_runtime/nacl_config.h" |
| 8 |
| 9 .text |
| 10 |
| 11 /* |
| 12 * This trusted code is linked into the service_runtime and |
| 13 * executed when switching from the service runtime to a nacl |
| 14 * module. This happens when a main nacl thread is created and starting to |
| 15 * execute the nacl code, or when nacl module is returning from a system |
| 16 * call. This piece of code lives in a service runtime part of address space. |
| 17 * The one and only argument is in register a0 |
| 18 * |
| 19 * a0 -- address of thread context (struct NaClThreadContext) |
| 20 */ |
| 21 |
| 22 DEFINE_GLOBAL_HIDDEN_IDENTIFIER(NaClSwitch): |
| 23 |
| 24 .set noreorder |
| 25 |
| 26 /* |
| 27 * We clear registers a1, a2, a3, t0, t1, t2, t3, t4, t5 and ra to avoid |
| 28 * information leaks. The remaining registers are overwritten by the code that |
| 29 * follows after. |
| 30 */ |
| 31 |
| 32 addu $a1, $zero, $zero |
| 33 addu $a2, $zero, $zero |
| 34 addu $a3, $zero, $zero |
| 35 addu $t0, $zero, $zero |
| 36 addu $t1, $zero, $zero |
| 37 addu $t2, $zero, $zero |
| 38 addu $t3, $zero, $zero |
| 39 addu $t4, $zero, $zero |
| 40 addu $t5, $zero, $zero |
| 41 addu $ra, $zero, $zero |
| 42 |
| 43 /* NACL_CALLEE_SAVE_LIST BEGIN */ |
| 44 lw $t6, 0($a0) |
| 45 lw $t7, 4($a0) |
| 46 lw $s0, 8($a0) |
| 47 lw $s1, 12($a0) |
| 48 lw $s2, 16($a0) |
| 49 lw $s3, 20($a0) |
| 50 lw $s4, 24($a0) |
| 51 lw $s5, 28($a0) |
| 52 lw $s6, 32($a0) |
| 53 lw $s7, 36($a0) |
| 54 lw $t8, 40($a0) |
| 55 lw $gp, 44($a0) |
| 56 lw $sp, 48($a0) |
| 57 lw $fp, 52($a0) |
| 58 /* NACL_CALLEE_SAVE_LIST END*/ |
| 59 |
| 60 lw $v0, 60($a0) /* context->sysret */ |
| 61 lw $v1, 64($a0) /* context->new_prog_ctr */ |
| 62 |
| 63 /* At startup, context->sysret contains not the the return value, but the |
| 64 first argument. Put it in a0. */ |
| 65 addu $a0, $v0, $zero |
| 66 |
| 67 /* Transfer control to untrusted code */ |
| 68 jr $v1 |
| 69 nop |
| 70 |
| 71 .set reorder |
| 72 |
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