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Diffstat (limited to 'arch/x86/boot/compressed/pgtable_64.c')
-rw-r--r--arch/x86/boot/compressed/pgtable_64.c94
1 files changed, 39 insertions, 55 deletions
diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index 2ac12ff41..51f957b24 100644
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -16,11 +16,6 @@ unsigned int __section(".data") pgdir_shift = 39;
unsigned int __section(".data") ptrs_per_p4d = 1;
#endif
-struct paging_config {
- unsigned long trampoline_start;
- unsigned long l5_required;
-};
-
/* Buffer to preserve trampoline memory */
static char trampoline_save[TRAMPOLINE_32BIT_SIZE];
@@ -29,11 +24,10 @@ static char trampoline_save[TRAMPOLINE_32BIT_SIZE];
* purposes.
*
* Avoid putting the pointer into .bss as it will be cleared between
- * paging_prepare() and extract_kernel().
+ * configure_5level_paging() and extract_kernel().
*/
unsigned long *trampoline_32bit __section(".data");
-extern struct boot_params *boot_params;
int cmdline_find_option_bool(const char *option);
static unsigned long find_trampoline_placement(void)
@@ -54,7 +48,7 @@ static unsigned long find_trampoline_placement(void)
*
* Only look for values in the legacy ROM for non-EFI system.
*/
- signature = (char *)&boot_params->efi_info.efi_loader_signature;
+ signature = (char *)&boot_params_ptr->efi_info.efi_loader_signature;
if (strncmp(signature, EFI32_LOADER_SIGNATURE, 4) &&
strncmp(signature, EFI64_LOADER_SIGNATURE, 4)) {
ebda_start = *(unsigned short *)0x40e << 4;
@@ -70,10 +64,10 @@ static unsigned long find_trampoline_placement(void)
bios_start = round_down(bios_start, PAGE_SIZE);
/* Find the first usable memory region under bios_start. */
- for (i = boot_params->e820_entries - 1; i >= 0; i--) {
+ for (i = boot_params_ptr->e820_entries - 1; i >= 0; i--) {
unsigned long new = bios_start;
- entry = &boot_params->e820_table[i];
+ entry = &boot_params_ptr->e820_table[i];
/* Skip all entries above bios_start. */
if (bios_start <= entry->addr)
@@ -106,12 +100,13 @@ static unsigned long find_trampoline_placement(void)
return bios_start - TRAMPOLINE_32BIT_SIZE;
}
-struct paging_config paging_prepare(void *rmode)
+asmlinkage void configure_5level_paging(struct boot_params *bp, void *pgtable)
{
- struct paging_config paging_config = {};
+ void (*toggle_la57)(void *cr3);
+ bool l5_required = false;
/* Initialize boot_params. Required for cmdline_find_option_bool(). */
- boot_params = rmode;
+ boot_params_ptr = bp;
/*
* Check if LA57 is desired and supported.
@@ -129,12 +124,22 @@ struct paging_config paging_prepare(void *rmode)
!cmdline_find_option_bool("no5lvl") &&
native_cpuid_eax(0) >= 7 &&
(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) {
- paging_config.l5_required = 1;
+ l5_required = true;
+
+ /* Initialize variables for 5-level paging */
+ __pgtable_l5_enabled = 1;
+ pgdir_shift = 48;
+ ptrs_per_p4d = 512;
}
- paging_config.trampoline_start = find_trampoline_placement();
+ /*
+ * The trampoline will not be used if the paging mode is already set to
+ * the desired one.
+ */
+ if (l5_required == !!(native_read_cr4() & X86_CR4_LA57))
+ return;
- trampoline_32bit = (unsigned long *)paging_config.trampoline_start;
+ trampoline_32bit = (unsigned long *)find_trampoline_placement();
/* Preserve trampoline memory */
memcpy(trampoline_save, trampoline_32bit, TRAMPOLINE_32BIT_SIZE);
@@ -143,32 +148,32 @@ struct paging_config paging_prepare(void *rmode)
memset(trampoline_32bit, 0, TRAMPOLINE_32BIT_SIZE);
/* Copy trampoline code in place */
- memcpy(trampoline_32bit + TRAMPOLINE_32BIT_CODE_OFFSET / sizeof(unsigned long),
+ toggle_la57 = memcpy(trampoline_32bit +
+ TRAMPOLINE_32BIT_CODE_OFFSET / sizeof(unsigned long),
&trampoline_32bit_src, TRAMPOLINE_32BIT_CODE_SIZE);
/*
+ * Avoid the need for a stack in the 32-bit trampoline code, by using
+ * LJMP rather than LRET to return back to long mode. LJMP takes an
+ * immediate absolute address, which needs to be adjusted based on the
+ * placement of the trampoline.
+ */
+ *(u32 *)((u8 *)toggle_la57 + trampoline_ljmp_imm_offset) +=
+ (unsigned long)toggle_la57;
+
+ /*
* The code below prepares page table in trampoline memory.
*
* The new page table will be used by trampoline code for switching
* from 4- to 5-level paging or vice versa.
- *
- * If switching is not required, the page table is unused: trampoline
- * code wouldn't touch CR3.
- */
-
- /*
- * We are not going to use the page table in trampoline memory if we
- * are already in the desired paging mode.
*/
- if (paging_config.l5_required == !!(native_read_cr4() & X86_CR4_LA57))
- goto out;
- if (paging_config.l5_required) {
+ if (l5_required) {
/*
* For 4- to 5-level paging transition, set up current CR3 as
* the first and the only entry in a new top-level page table.
*/
- trampoline_32bit[TRAMPOLINE_32BIT_PGTABLE_OFFSET] = __native_read_cr3() | _PAGE_TABLE_NOENC;
+ *trampoline_32bit = __native_read_cr3() | _PAGE_TABLE_NOENC;
} else {
unsigned long src;
@@ -181,38 +186,17 @@ struct paging_config paging_prepare(void *rmode)
* may be above 4G.
*/
src = *(unsigned long *)__native_read_cr3() & PAGE_MASK;
- memcpy(trampoline_32bit + TRAMPOLINE_32BIT_PGTABLE_OFFSET / sizeof(unsigned long),
- (void *)src, PAGE_SIZE);
+ memcpy(trampoline_32bit, (void *)src, PAGE_SIZE);
}
-out:
- return paging_config;
-}
-
-void cleanup_trampoline(void *pgtable)
-{
- void *trampoline_pgtable;
-
- trampoline_pgtable = trampoline_32bit + TRAMPOLINE_32BIT_PGTABLE_OFFSET / sizeof(unsigned long);
+ toggle_la57(trampoline_32bit);
/*
- * Move the top level page table out of trampoline memory,
- * if it's there.
+ * Move the top level page table out of trampoline memory.
*/
- if ((void *)__native_read_cr3() == trampoline_pgtable) {
- memcpy(pgtable, trampoline_pgtable, PAGE_SIZE);
- native_write_cr3((unsigned long)pgtable);
- }
+ memcpy(pgtable, trampoline_32bit, PAGE_SIZE);
+ native_write_cr3((unsigned long)pgtable);
/* Restore trampoline memory */
memcpy(trampoline_32bit, trampoline_save, TRAMPOLINE_32BIT_SIZE);
-
- /* Initialize variables for 5-level paging */
-#ifdef CONFIG_X86_5LEVEL
- if (__read_cr4() & X86_CR4_LA57) {
- __pgtable_l5_enabled = 1;
- pgdir_shift = 48;
- ptrs_per_p4d = 512;
- }
-#endif
}