ArmPlatformPkg: clear frame pointer in startup code
[mirror_edk2.git] / ArmPlatformPkg / PrePi / AArch64 / ModuleEntryPoint.S
1 //
2 // Copyright (c) 2011-2015, ARM Limited. All rights reserved.
3 //
4 // This program and the accompanying materials
5 // are licensed and made available under the terms and conditions of the BSD License
6 // which accompanies this distribution. The full text of the license may be found at
7 // http://opensource.org/licenses/bsd-license.php
8 //
9 // THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
10 // WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
11 //
12 //
13
14 #include <AsmMacroIoLibV8.h>
15
16 ASM_FUNC(_ModuleEntryPoint)
17 // Do early platform specific actions
18 bl ASM_PFX(ArmPlatformPeiBootAction)
19
20 // Get ID of this CPU in Multicore system
21 bl ASM_PFX(ArmReadMpidr)
22 // Keep a copy of the MpId register value
23 mov x10, x0
24
25 _SetSVCMode:
26 // Check if we can install the stack at the top of the System Memory or if we need
27 // to install the stacks at the bottom of the Firmware Device (case the FD is located
28 // at the top of the DRAM)
29 _SystemMemoryEndInit:
30 ldr x1, mSystemMemoryEnd
31
32 _SetupStackPosition:
33 // r1 = SystemMemoryTop
34
35 // Calculate Top of the Firmware Device
36 MOV64 (x2, FixedPcdGet64(PcdFdBaseAddress))
37 MOV32 (x3, FixedPcdGet32(PcdFdSize) - 1)
38 sub x3, x3, #1
39 add x3, x3, x2 // x3 = FdTop = PcdFdBaseAddress + PcdFdSize
40
41 // UEFI Memory Size (stacks are allocated in this region)
42 MOV32 (x4, FixedPcdGet32(PcdSystemMemoryUefiRegionSize))
43
44 //
45 // Reserve the memory for the UEFI region (contain stacks on its top)
46 //
47
48 // Calculate how much space there is between the top of the Firmware and the Top of the System Memory
49 subs x0, x1, x3 // x0 = SystemMemoryTop - FdTop
50 b.mi _SetupStack // Jump if negative (FdTop > SystemMemoryTop). Case when the PrePi is in XIP memory outside of the DRAM
51 cmp x0, x4
52 b.ge _SetupStack
53
54 // Case the top of stacks is the FdBaseAddress
55 mov x1, x2
56
57 _SetupStack:
58 // x1 contains the top of the stack (and the UEFI Memory)
59
60 // Because the 'push' instruction is equivalent to 'stmdb' (decrement before), we need to increment
61 // one to the top of the stack. We check if incrementing one does not overflow (case of DRAM at the
62 // top of the memory space)
63 adds x11, x1, #1
64 b.cs _SetupOverflowStack
65
66 _SetupAlignedStack:
67 mov x1, x11
68 b _GetBaseUefiMemory
69
70 _SetupOverflowStack:
71 // Case memory at the top of the address space. Ensure the top of the stack is EFI_PAGE_SIZE
72 // aligned (4KB)
73 and x1, x1, ~EFI_PAGE_MASK
74
75 _GetBaseUefiMemory:
76 // Calculate the Base of the UEFI Memory
77 sub x11, x1, x4
78
79 _GetStackBase:
80 // r1 = The top of the Mpcore Stacks
81 // Stack for the primary core = PrimaryCoreStack
82 MOV32 (x2, FixedPcdGet32(PcdCPUCorePrimaryStackSize))
83 sub x12, x1, x2
84
85 // Stack for the secondary core = Number of Cores - 1
86 MOV32 (x1, (FixedPcdGet32(PcdCoreCount) - 1) * FixedPcdGet32(PcdCPUCoreSecondaryStackSize))
87 sub x12, x12, x1
88
89 // x12 = The base of the MpCore Stacks (primary stack & secondary stacks)
90 mov x0, x12
91 mov x1, x10
92 //ArmPlatformStackSet(StackBase, MpId, PrimaryStackSize, SecondaryStackSize)
93 MOV32 (x2, FixedPcdGet32(PcdCPUCorePrimaryStackSize))
94 MOV32 (x3, FixedPcdGet32(PcdCPUCoreSecondaryStackSize))
95 bl ASM_PFX(ArmPlatformStackSet)
96
97 // Is it the Primary Core ?
98 mov x0, x10
99 bl ASM_PFX(ArmPlatformIsPrimaryCore)
100 cmp x0, #1
101 bne _PrepareArguments
102
103 _PrepareArguments:
104 mov x0, x10
105 mov x1, x11
106 mov x2, x12
107
108 // Move sec startup address into a data register
109 // Ensure we're jumping to FV version of the code (not boot remapped alias)
110 ldr x4, =ASM_PFX(CEntryPoint)
111
112 // Set the frame pointer to NULL so any backtraces terminate here
113 mov x29, xzr
114
115 // Jump to PrePiCore C code
116 // x0 = MpId
117 // x1 = UefiMemoryBase
118 // x2 = StacksBase
119 blr x4
120
121 _NeverReturn:
122 b _NeverReturn