1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2013 Linaro Ltd;  <roy.franz@linaro.org>
4  */
5 #include <linux/efi.h>
6 #include <asm/efi.h>
7 
8 #include "efistub.h"
9 
10 static efi_guid_t cpu_state_guid = LINUX_EFI_ARM_CPU_STATE_TABLE_GUID;
11 
12 struct efi_arm_entry_state *efi_entry_state;
13 
14 static void get_cpu_state(u32 *cpsr, u32 *sctlr)
15 {
16 	asm("mrs %0, cpsr" : "=r"(*cpsr));
17 	if ((*cpsr & MODE_MASK) == HYP_MODE)
18 		asm("mrc p15, 4, %0, c1, c0, 0" : "=r"(*sctlr));
19 	else
20 		asm("mrc p15, 0, %0, c1, c0, 0" : "=r"(*sctlr));
21 }
22 
23 efi_status_t check_platform_features(void)
24 {
25 	efi_status_t status;
26 	u32 cpsr, sctlr;
27 	int block;
28 
29 	get_cpu_state(&cpsr, &sctlr);
30 
31 	efi_info("Entering in %s mode with MMU %sabled\n",
32 		 ((cpsr & MODE_MASK) == HYP_MODE) ? "HYP" : "SVC",
33 		 (sctlr & 1) ? "en" : "dis");
34 
35 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
36 			     sizeof(*efi_entry_state),
37 			     (void **)&efi_entry_state);
38 	if (status != EFI_SUCCESS) {
39 		efi_err("allocate_pool() failed\n");
40 		return status;
41 	}
42 
43 	efi_entry_state->cpsr_before_ebs = cpsr;
44 	efi_entry_state->sctlr_before_ebs = sctlr;
45 
46 	status = efi_bs_call(install_configuration_table, &cpu_state_guid,
47 			     efi_entry_state);
48 	if (status != EFI_SUCCESS) {
49 		efi_err("install_configuration_table() failed\n");
50 		goto free_state;
51 	}
52 
53 	/* non-LPAE kernels can run anywhere */
54 	if (!IS_ENABLED(CONFIG_ARM_LPAE))
55 		return EFI_SUCCESS;
56 
57 	/* LPAE kernels need compatible hardware */
58 	block = cpuid_feature_extract(CPUID_EXT_MMFR0, 0);
59 	if (block < 5) {
60 		efi_err("This LPAE kernel is not supported by your CPU\n");
61 		status = EFI_UNSUPPORTED;
62 		goto drop_table;
63 	}
64 	return EFI_SUCCESS;
65 
66 drop_table:
67 	efi_bs_call(install_configuration_table, &cpu_state_guid, NULL);
68 free_state:
69 	efi_bs_call(free_pool, efi_entry_state);
70 	return status;
71 }
72 
73 void efi_handle_post_ebs_state(void)
74 {
75 	get_cpu_state(&efi_entry_state->cpsr_after_ebs,
76 		      &efi_entry_state->sctlr_after_ebs);
77 }
78 
79 static efi_guid_t screen_info_guid = LINUX_EFI_ARM_SCREEN_INFO_TABLE_GUID;
80 
81 struct screen_info *alloc_screen_info(void)
82 {
83 	struct screen_info *si;
84 	efi_status_t status;
85 
86 	/*
87 	 * Unlike on arm64, where we can directly fill out the screen_info
88 	 * structure from the stub, we need to allocate a buffer to hold
89 	 * its contents while we hand over to the kernel proper from the
90 	 * decompressor.
91 	 */
92 	status = efi_bs_call(allocate_pool, EFI_RUNTIME_SERVICES_DATA,
93 			     sizeof(*si), (void **)&si);
94 
95 	if (status != EFI_SUCCESS)
96 		return NULL;
97 
98 	status = efi_bs_call(install_configuration_table,
99 			     &screen_info_guid, si);
100 	if (status == EFI_SUCCESS)
101 		return si;
102 
103 	efi_bs_call(free_pool, si);
104 	return NULL;
105 }
106 
107 void free_screen_info(struct screen_info *si)
108 {
109 	if (!si)
110 		return;
111 
112 	efi_bs_call(install_configuration_table, &screen_info_guid, NULL);
113 	efi_bs_call(free_pool, si);
114 }
115 
116 efi_status_t handle_kernel_image(unsigned long *image_addr,
117 				 unsigned long *image_size,
118 				 unsigned long *reserve_addr,
119 				 unsigned long *reserve_size,
120 				 efi_loaded_image_t *image,
121 				 efi_handle_t image_handle)
122 {
123 	const int slack = TEXT_OFFSET - 5 * PAGE_SIZE;
124 	int alloc_size = MAX_UNCOMP_KERNEL_SIZE + EFI_PHYS_ALIGN;
125 	unsigned long alloc_base, kernel_base;
126 	efi_status_t status;
127 
128 	/*
129 	 * Allocate space for the decompressed kernel as low as possible.
130 	 * The region should be 16 MiB aligned, but the first 'slack' bytes
131 	 * are not used by Linux, so we allow those to be occupied by the
132 	 * firmware.
133 	 */
134 	status = efi_low_alloc_above(alloc_size, EFI_PAGE_SIZE, &alloc_base, 0x0);
135 	if (status != EFI_SUCCESS) {
136 		efi_err("Unable to allocate memory for uncompressed kernel.\n");
137 		return status;
138 	}
139 
140 	if ((alloc_base % EFI_PHYS_ALIGN) > slack) {
141 		/*
142 		 * More than 'slack' bytes are already occupied at the base of
143 		 * the allocation, so we need to advance to the next 16 MiB block.
144 		 */
145 		kernel_base = round_up(alloc_base, EFI_PHYS_ALIGN);
146 		efi_info("Free memory starts at 0x%lx, setting kernel_base to 0x%lx\n",
147 			 alloc_base, kernel_base);
148 	} else {
149 		kernel_base = round_down(alloc_base, EFI_PHYS_ALIGN);
150 	}
151 
152 	*reserve_addr = kernel_base + slack;
153 	*reserve_size = MAX_UNCOMP_KERNEL_SIZE;
154 
155 	/* now free the parts that we will not use */
156 	if (*reserve_addr > alloc_base) {
157 		efi_bs_call(free_pages, alloc_base,
158 			    (*reserve_addr - alloc_base) / EFI_PAGE_SIZE);
159 		alloc_size -= *reserve_addr - alloc_base;
160 	}
161 	efi_bs_call(free_pages, *reserve_addr + MAX_UNCOMP_KERNEL_SIZE,
162 		    (alloc_size - MAX_UNCOMP_KERNEL_SIZE) / EFI_PAGE_SIZE);
163 
164 	*image_addr = kernel_base + TEXT_OFFSET;
165 	*image_size = 0;
166 
167 	efi_debug("image addr == 0x%lx, reserve_addr == 0x%lx\n",
168 		  *image_addr, *reserve_addr);
169 
170 	return EFI_SUCCESS;
171 }
172