diff mbox series

[v5,13/27] x86/boot: Split trampoline and pt init code

Message ID c3ec00c28fcb540124f324d8ba35eb62601655de.1678785672.git.baskov@ispras.ru
State New
Headers show
Series x86_64: Improvements at compressed kernel stage | expand

Commit Message

Evgeniy Baskov March 14, 2023, 10:13 a.m. UTC 
When allocating trampoline from libstub trampoline allocation is
performed separately, so it needs to be skipped.

Split trampoline initialization and allocation code into two
functions to make them invokable separately.

Tested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Evgeniy Baskov <baskov@ispras.ru>
---
 arch/x86/boot/compressed/pgtable_64.c | 69 ++++++++++++++++-----------
 1 file changed, 42 insertions(+), 27 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index c7cf5a1059a8..d71a62b7cf06 100644
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -106,12 +106,8 @@  static unsigned long find_trampoline_placement(void)
 	return bios_start - TRAMPOLINE_32BIT_SIZE;
 }
 
-struct paging_config paging_prepare(void *rmode)
+bool trampoline_pgtable_init(struct boot_params *boot_params)
 {
-	struct paging_config paging_config = {};
-
-	/* Initialize boot_params. Required for cmdline_find_option_bool(). */
-	boot_params = rmode;
 
 	/*
 	 * Check if LA57 is desired and supported.
@@ -125,26 +121,10 @@  struct paging_config paging_prepare(void *rmode)
 	 *
 	 * That's substitute for boot_cpu_has() in early boot code.
 	 */
-	if (IS_ENABLED(CONFIG_X86_5LEVEL) &&
-			!cmdline_find_option_bool("no5lvl") &&
-			native_cpuid_eax(0) >= 7 &&
-			(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) {
-		paging_config.l5_required = 1;
-	}
-
-	paging_config.trampoline_start = find_trampoline_placement();
-
-	trampoline_32bit = (unsigned long *)paging_config.trampoline_start;
-
-	/* Preserve trampoline memory */
-	memcpy(trampoline_save, trampoline_32bit, TRAMPOLINE_32BIT_SIZE);
-
-	/* Clear trampoline memory first */
-	memset(trampoline_32bit, 0, TRAMPOLINE_32BIT_SIZE);
-
-	/* Copy trampoline code in place */
-	memcpy(trampoline_32bit + TRAMPOLINE_32BIT_CODE_OFFSET / sizeof(unsigned long),
-			&trampoline_32bit_src, TRAMPOLINE_32BIT_CODE_SIZE);
+	bool l5_required = IS_ENABLED(CONFIG_X86_5LEVEL) &&
+			   !cmdline_find_option_bool("no5lvl") &&
+			   native_cpuid_eax(0) >= 7 &&
+			   (native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)));
 
 	/*
 	 * The code below prepares page table in trampoline memory.
@@ -160,10 +140,10 @@  struct paging_config paging_prepare(void *rmode)
 	 * 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))
+	if (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.
@@ -185,6 +165,41 @@  struct paging_config paging_prepare(void *rmode)
 		       (void *)src, PAGE_SIZE);
 	}
 
+out:
+	return l5_required;
+}
+
+struct paging_config paging_prepare(void *rmode)
+{
+	struct paging_config paging_config = {};
+
+	/* Initialize boot_params. Required for cmdline_find_option_bool(). */
+	boot_params = rmode;
+
+	/*
+	 * We only need to find trampoline placement, if we have
+	 * not already done it from libstub.
+	 */
+
+	paging_config.trampoline_start = find_trampoline_placement();
+	trampoline_32bit = (unsigned long *)paging_config.trampoline_start;
+
+	/*
+	 * Preserve trampoline memory. When trampoline is located in memory
+	 * owned by us, i.e. allocated in EFISTUB, we don't care about previous
+	 * contents of this memory so copying can also be skipped.
+	 */
+	memcpy(trampoline_save, trampoline_32bit, TRAMPOLINE_32BIT_SIZE);
+
+	/* Clear trampoline memory first */
+	memset(trampoline_32bit, 0, TRAMPOLINE_32BIT_SIZE);
+
+	/* Copy trampoline code in place */
+	memcpy(trampoline_32bit + TRAMPOLINE_32BIT_CODE_OFFSET / sizeof(unsigned long),
+			&trampoline_32bit_src, TRAMPOLINE_32BIT_CODE_SIZE);
+
+	paging_config.l5_required = trampoline_pgtable_init(boot_params);
+
 out:
 	return paging_config;
 }