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2024-05-10 cde9070d9970eef1f7ec2360586c802a16230ad8 
 kernel/arch/x86/boot/compressed/head_32.S
....@@ -33,52 +33,19 @@
3333 #include <asm/bootparam.h>
3434 
3535 /*
36
- * The 32-bit x86 assembler in binutils 2.26 will generate R_386_GOT32X
37
- * relocation to get the symbol address in PIC.  When the compressed x86
38
- * kernel isn't built as PIC, the linker optimizes R_386_GOT32X
39
- * relocations to their fixed symbol addresses.  However, when the
40
- * compressed x86 kernel is loaded at a different address, it leads
41
- * to the following load failure:
42
- *
43
- *   Failed to allocate space for phdrs
44
- *
45
- * during the decompression stage.
46
- *
47
- * If the compressed x86 kernel is relocatable at run-time, it should be
48
- * compiled with -fPIE, instead of -fPIC, if possible and should be built as
49
- * Position Independent Executable (PIE) so that linker won't optimize
50
- * R_386_GOT32X relocation to its fixed symbol address.  Older
51
- * linkers generate R_386_32 relocations against locally defined symbols,
52
- * _bss, _ebss, _got, _egot and _end, in PIE.  It isn't wrong, just less
53
- * optimal than R_386_RELATIVE.  But the x86 kernel fails to properly handle
54
- * R_386_32 relocations when relocating the kernel.  To generate
55
- * R_386_RELATIVE relocations, we mark _bss, _ebss, _got, _egot and _end as
56
- * hidden:
36
+ * These symbols needed to be marked as .hidden to prevent the BFD linker from
37
+ * generating R_386_32 (rather than R_386_RELATIVE) relocations for them when
38
+ * the 32-bit compressed kernel is linked as PIE. This is no longer necessary,
39
+ * but it doesn't hurt to keep them .hidden.
5740  */
5841 	.hidden _bss
5942 	.hidden _ebss
60
-	.hidden _got
61
-	.hidden _egot
6243 	.hidden _end
6344 
6445 	__HEAD
65
-ENTRY(startup_32)
46
+SYM_FUNC_START(startup_32)
6647 	cld
67
-	/*
68
-	 * Test KEEP_SEGMENTS flag to see if the bootloader is asking
69
-	 * us to not reload segments
70
-	 */
71
-	testb	$KEEP_SEGMENTS, BP_loadflags(%esi)
72
-	jnz	1f
73
-
7448 	cli
75
-	movl	$__BOOT_DS, %eax
76
-	movl	%eax, %ds
77
-	movl	%eax, %es
78
-	movl	%eax, %fs
79
-	movl	%eax, %gs
80
-	movl	%eax, %ss
81
-1:
8249 
8350 /*
8451  * Calculate the delta between where we were compiled to run
....@@ -90,17 +57,46 @@
9057  */
9158 	leal	(BP_scratch+4)(%esi), %esp
9259 	call	1f
93
-1:	popl	%ebp
94
-	subl	$1b, %ebp
60
+1:	popl	%edx
61
+	addl	$_GLOBAL_OFFSET_TABLE_+(.-1b), %edx
62
+
63
+	/* Load new GDT */
64
+	leal	gdt@GOTOFF(%edx), %eax
65
+	movl	%eax, 2(%eax)
66
+	lgdt	(%eax)
67
+
68
+	/* Load segment registers with our descriptors */
69
+	movl	$__BOOT_DS, %eax
70
+	movl	%eax, %ds
71
+	movl	%eax, %es
72
+	movl	%eax, %fs
73
+	movl	%eax, %gs
74
+	movl	%eax, %ss
9575 
9676 /*
97
- * %ebp contains the address we are loaded at by the boot loader and %ebx
98
- * contains the address where we should move the kernel image temporarily
99
- * for safe in-place decompression.
77
+ * %edx contains the address we are loaded at by the boot loader (plus the
78
+ * offset to the GOT).  The below code calculates %ebx to be the address where
79
+ * we should move the kernel image temporarily for safe in-place decompression
80
+ * (again, plus the offset to the GOT).
81
+ *
82
+ * %ebp is calculated to be the address that the kernel will be decompressed to.
10083  */
10184 
10285 #ifdef CONFIG_RELOCATABLE
103
-	movl	%ebp, %ebx
86
+	leal	startup_32@GOTOFF(%edx), %ebx
87
+
88
+#ifdef CONFIG_EFI_STUB
89
+/*
90
+ * If we were loaded via the EFI LoadImage service, startup_32() will be at an
91
+ * offset to the start of the space allocated for the image. efi_pe_entry() will
92
+ * set up image_offset to tell us where the image actually starts, so that we
93
+ * can use the full available buffer.
94
+ *	image_offset = startup_32 - image_base
95
+ * Otherwise image_offset will be zero and has no effect on the calculations.
96
+ */
97
+	subl    image_offset@GOTOFF(%edx), %ebx
98
+#endif
99
+
104100 	movl	BP_kernel_alignment(%esi), %eax
105101 	decl	%eax
106102 	addl    %eax, %ebx
....@@ -112,13 +108,13 @@
112108 	movl	$LOAD_PHYSICAL_ADDR, %ebx
113109 1:
114110 
111
+	movl	%ebx, %ebp	// Save the output address for later
115112 	/* Target address to relocate to for decompression */
116
-	movl    BP_init_size(%esi), %eax
117
-	subl    $_end, %eax
118
-	addl    %eax, %ebx
113
+	addl    BP_init_size(%esi), %ebx
114
+	subl    $_end@GOTOFF, %ebx
119115 
120116 	/* Set up the stack */
121
-	leal	boot_stack_end(%ebx), %esp
117
+	leal	boot_stack_end@GOTOFF(%ebx), %esp
122118 
123119 	/* Zero EFLAGS */
124120 	pushl	$0
....@@ -129,8 +125,8 @@
129125  * where decompression in place becomes safe.
130126  */
131127 	pushl	%esi
132
-	leal	(_bss-4)(%ebp), %esi
133
-	leal	(_bss-4)(%ebx), %edi
128
+	leal	(_bss@GOTOFF-4)(%edx), %esi
129
+	leal	(_bss@GOTOFF-4)(%ebx), %edi
134130 	movl	$(_bss - startup_32), %ecx
135131 	shrl	$2, %ecx
136132 	std
....@@ -138,122 +134,61 @@
138134 	cld
139135 	popl	%esi
140136 
137
+	/*
138
+	 * The GDT may get overwritten either during the copy we just did or
139
+	 * during extract_kernel below. To avoid any issues, repoint the GDTR
140
+	 * to the new copy of the GDT.
141
+	 */
142
+	leal	gdt@GOTOFF(%ebx), %eax
143
+	movl	%eax, 2(%eax)
144
+	lgdt	(%eax)
145
+
141146 /*
142147  * Jump to the relocated address.
143148  */
144
-	leal	relocated(%ebx), %eax
149
+	leal	.Lrelocated@GOTOFF(%ebx), %eax
145150 	jmp	*%eax
146
-ENDPROC(startup_32)
151
+SYM_FUNC_END(startup_32)
147152 
148153 #ifdef CONFIG_EFI_STUB
149
-/*
150
- * We don't need the return address, so set up the stack so efi_main() can find
151
- * its arguments.
152
- */
153
-ENTRY(efi_pe_entry)
154
+SYM_FUNC_START(efi32_stub_entry)
155
+SYM_FUNC_START_ALIAS(efi_stub_entry)
154156 	add	$0x4, %esp
155
-
156
-	call	1f
157
-1:	popl	%esi
158
-	subl	$1b, %esi
159
-
160
-	popl	%ecx
161
-	movl	%ecx, efi32_config(%esi)	/* Handle */
162
-	popl	%ecx
163
-	movl	%ecx, efi32_config+8(%esi)	/* EFI System table pointer */
164
-
165
-	/* Relocate efi_config->call() */
166
-	leal	efi32_config(%esi), %eax
167
-	add	%esi, 40(%eax)
168
-	pushl	%eax
169
-
170
-	call	make_boot_params
171
-	cmpl	$0, %eax
172
-	je	fail
173
-	movl	%esi, BP_code32_start(%eax)
174
-	popl	%ecx
175
-	pushl	%eax
176
-	pushl	%ecx
177
-	jmp	2f		/* Skip efi_config initialization */
178
-ENDPROC(efi_pe_entry)
179
-
180
-ENTRY(efi32_stub_entry)
181
-	add	$0x4, %esp
182
-	popl	%ecx
183
-	popl	%edx
184
-
185
-	call	1f
186
-1:	popl	%esi
187
-	subl	$1b, %esi
188
-
189
-	movl	%ecx, efi32_config(%esi)	/* Handle */
190
-	movl	%edx, efi32_config+8(%esi)	/* EFI System table pointer */
191
-
192
-	/* Relocate efi_config->call() */
193
-	leal	efi32_config(%esi), %eax
194
-	add	%esi, 40(%eax)
195
-	pushl	%eax
196
-2:
157
+	movl	8(%esp), %esi	/* save boot_params pointer */
197158 	call	efi_main
198
-	cmpl	$0, %eax
199
-	movl	%eax, %esi
200
-	jne	2f
201
-fail:
202
-	/* EFI init failed, so hang. */
203
-	hlt
204
-	jmp	fail
205
-2:
206
-	movl	BP_code32_start(%esi), %eax
207
-	leal	startup_32(%eax), %eax
159
+	/* efi_main returns the possibly relocated address of startup_32 */
208160 	jmp	*%eax
209
-ENDPROC(efi32_stub_entry)
161
+SYM_FUNC_END(efi32_stub_entry)
162
+SYM_FUNC_END_ALIAS(efi_stub_entry)
210163 #endif
211164 
212165 	.text
213
-relocated:
166
+SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
214167 
215168 /*
216169  * Clear BSS (stack is currently empty)
217170  */
218171 	xorl	%eax, %eax
219
-	leal	_bss(%ebx), %edi
220
-	leal	_ebss(%ebx), %ecx
172
+	leal	_bss@GOTOFF(%ebx), %edi
173
+	leal	_ebss@GOTOFF(%ebx), %ecx
221174 	subl	%edi, %ecx
222175 	shrl	$2, %ecx
223176 	rep	stosl
224177 
225178 /*
226
- * Adjust our own GOT
227
- */
228
-	leal	_got(%ebx), %edx
229
-	leal	_egot(%ebx), %ecx
230
-1:
231
-	cmpl	%ecx, %edx
232
-	jae	2f
233
-	addl	%ebx, (%edx)
234
-	addl	$4, %edx
235
-	jmp	1b
236
-2:
237
-
238
-/*
239179  * Do the extraction, and jump to the new kernel..
240180  */
241
-				/* push arguments for extract_kernel: */
242
-	pushl	$z_output_len	/* decompressed length, end of relocs */
181
+	/* push arguments for extract_kernel: */
243182 
244
-	movl    BP_init_size(%esi), %eax
245
-	subl    $_end, %eax
246
-	movl    %ebx, %ebp
247
-	subl    %eax, %ebp
248
-	pushl	%ebp		/* output address */
249
-
250
-	pushl	$z_input_len	/* input_len */
251
-	leal	input_data(%ebx), %eax
252
-	pushl	%eax		/* input_data */
253
-	leal	boot_heap(%ebx), %eax
254
-	pushl	%eax		/* heap area */
255
-	pushl	%esi		/* real mode pointer */
256
-	call	extract_kernel	/* returns kernel location in %eax */
183
+	pushl	output_len@GOTOFF(%ebx)	/* decompressed length, end of relocs */
184
+	pushl	%ebp			/* output address */
185
+	pushl	input_len@GOTOFF(%ebx)	/* input_len */
186
+	leal	input_data@GOTOFF(%ebx), %eax
187
+	pushl	%eax			/* input_data */
188
+	leal	boot_heap@GOTOFF(%ebx), %eax
189
+	pushl	%eax			/* heap area */
190
+	pushl	%esi			/* real mode pointer */
191
+	call	extract_kernel		/* returns kernel location in %eax */
257192 	addl	$24, %esp
258193 
259194 /*
....@@ -261,14 +196,21 @@
261196  */
262197 	xorl	%ebx, %ebx
263198 	jmp	*%eax
199
+SYM_FUNC_END(.Lrelocated)
200
+
201
+	.data
202
+	.balign	8
203
+SYM_DATA_START_LOCAL(gdt)
204
+	.word	gdt_end - gdt - 1
205
+	.long	0
206
+	.word	0
207
+	.quad	0x0000000000000000	/* Reserved */
208
+	.quad	0x00cf9a000000ffff	/* __KERNEL_CS */
209
+	.quad	0x00cf92000000ffff	/* __KERNEL_DS */
210
+SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)
264211 
265212 #ifdef CONFIG_EFI_STUB
266
-	.data
267
-efi32_config:
268
-	.fill 5,8,0
269
-	.long efi_call_phys
270
-	.long 0
271
-	.byte 0
213
+SYM_DATA(image_offset, .long 0)
272214 #endif
273215 
274216 /*