Merge tag 'x86-urgent-2025-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull misc x86 fixes from Ingo Molnar:

 - Fix 32-bit kernel boot crash if passed physical memory with more than
   32 address bits

 - Fix Xen PV crash

 - Work around build bug in certain limited build environments

 - Fix CTEST instruction decoding in insn_decoder_test

* tag 'x86-urgent-2025-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/insn: Fix CTEST instruction decoding
  x86/boot: Work around broken busybox 'truncate' tool
  x86/mm: Fix _pgd_alloc() for Xen PV mode
  x86/e820: Discard high memory that can't be addressed by 32-bit systems

Author: torvalds

arch/x86/boot/Makefile

@@ -59,7 +59,7 @@ KBUILD_CFLAGS	+= $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
 $(obj)/bzImage: asflags-y  := $(SVGA_MODE)
 
 quiet_cmd_image = BUILD   $@
-      cmd_image = cp $< $@; truncate -s %4K $@; cat $(obj)/vmlinux.bin >>$@
+      cmd_image = (dd if=$< bs=4k conv=sync status=none; cat $(filter-out $<,$(real-prereqs))) >$@
 
 $(obj)/bzImage: $(obj)/setup.bin $(obj)/vmlinux.bin FORCE
 	$(call if_changed,image)

arch/x86/include/asm/pgalloc.h

@@ -6,6 +6,8 @@
 #include <linux/mm.h>		/* for struct page */
 #include <linux/pagemap.h>
 
+#include <asm/cpufeature.h>
+
 #define __HAVE_ARCH_PTE_ALLOC_ONE
 #define __HAVE_ARCH_PGD_FREE
 #include <asm-generic/pgalloc.h>
@@ -29,16 +31,17 @@ static inline void paravirt_release_pud(unsigned long pfn) {}
 static inline void paravirt_release_p4d(unsigned long pfn) {}
 #endif
 
-#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
 /*
- * Instead of one PGD, we acquire two PGDs.  Being order-1, it is
- * both 8k in size and 8k-aligned.  That lets us just flip bit 12
- * in a pointer to swap between the two 4k halves.
+ * In case of Page Table Isolation active, we acquire two PGDs instead of one.
+ * Being order-1, it is both 8k in size and 8k-aligned.  That lets us just
+ * flip bit 12 in a pointer to swap between the two 4k halves.
  */
-#define PGD_ALLOCATION_ORDER 1
-#else
-#define PGD_ALLOCATION_ORDER 0
-#endif
+static inline unsigned int pgd_allocation_order(void)
+{
+	if (cpu_feature_enabled(X86_FEATURE_PTI))
+		return 1;
+	return 0;
+}
 
 /*
  * Allocate and free page tables.

arch/x86/kernel/e820.c

@@ -1299,6 +1299,14 @@ void __init e820__memblock_setup(void)
 		memblock_add(entry->addr, entry->size);
 	}
 
+	/*
+	 * 32-bit systems are limited to 4BG of memory even with HIGHMEM and
+	 * to even less without it.
+	 * Discard memory after max_pfn - the actual limit detected at runtime.
+	 */
+	if (IS_ENABLED(CONFIG_X86_32))
+		memblock_remove(PFN_PHYS(max_pfn), -1);
+
 	/* Throw away partial pages: */
 	memblock_trim_memory(PAGE_SIZE);
 

arch/x86/kernel/machine_kexec_32.c

@@ -42,7 +42,7 @@ static void load_segments(void)
 
 static void machine_kexec_free_page_tables(struct kimage *image)
 {
-	free_pages((unsigned long)image->arch.pgd, PGD_ALLOCATION_ORDER);
+	free_pages((unsigned long)image->arch.pgd, pgd_allocation_order());
 	image->arch.pgd = NULL;
 #ifdef CONFIG_X86_PAE
 	free_page((unsigned long)image->arch.pmd0);
@@ -59,7 +59,7 @@ static void machine_kexec_free_page_tables(struct kimage *image)
 static int machine_kexec_alloc_page_tables(struct kimage *image)
 {
 	image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
-						    PGD_ALLOCATION_ORDER);
+						    pgd_allocation_order());
 #ifdef CONFIG_X86_PAE
 	image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
 	image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);

arch/x86/lib/x86-opcode-map.txt

@@ -996,8 +996,8 @@ AVXcode: 4
 83: Grp1 Ev,Ib (1A),(es)
 # CTESTSCC instructions are: CTESTB, CTESTBE, CTESTF, CTESTL, CTESTLE, CTESTNB, CTESTNBE, CTESTNL,
 #			     CTESTNLE, CTESTNO, CTESTNS, CTESTNZ, CTESTO, CTESTS, CTESTT, CTESTZ
-84: CTESTSCC (ev)
-85: CTESTSCC (es) | CTESTSCC (66),(es)
+84: CTESTSCC Eb,Gb (ev)
+85: CTESTSCC Ev,Gv (es) | CTESTSCC Ev,Gv (66),(es)
 88: POPCNT Gv,Ev (es) | POPCNT Gv,Ev (66),(es)
 8f: POP2 Bq,Rq (000),(11B),(ev)
 a5: SHLD Ev,Gv,CL (es) | SHLD Ev,Gv,CL (66),(es)

arch/x86/mm/pgtable.c

@@ -360,7 +360,7 @@ static inline pgd_t *_pgd_alloc(struct mm_struct *mm)
 	 * We allocate one page for pgd.
 	 */
 	if (!SHARED_KERNEL_PMD)
-		return __pgd_alloc(mm, PGD_ALLOCATION_ORDER);
+		return __pgd_alloc(mm, pgd_allocation_order());
 
 	/*
 	 * Now PAE kernel is not running as a Xen domain. We can allocate
@@ -380,7 +380,7 @@ static inline void _pgd_free(struct mm_struct *mm, pgd_t *pgd)
 
 static inline pgd_t *_pgd_alloc(struct mm_struct *mm)
 {
-	return __pgd_alloc(mm, PGD_ALLOCATION_ORDER);
+	return __pgd_alloc(mm, pgd_allocation_order());
 }
 
 static inline void _pgd_free(struct mm_struct *mm, pgd_t *pgd)

arch/x86/platform/efi/efi_64.c

@@ -73,7 +73,7 @@ int __init efi_alloc_page_tables(void)
 	gfp_t gfp_mask;
 
 	gfp_mask = GFP_KERNEL | __GFP_ZERO;
-	efi_pgd = (pgd_t *)__get_free_pages(gfp_mask, PGD_ALLOCATION_ORDER);
+	efi_pgd = (pgd_t *)__get_free_pages(gfp_mask, pgd_allocation_order());
 	if (!efi_pgd)
 		goto fail;
 
@@ -96,7 +96,7 @@ int __init efi_alloc_page_tables(void)
 	if (pgtable_l5_enabled())
 		free_page((unsigned long)pgd_page_vaddr(*pgd));
 free_pgd:
-	free_pages((unsigned long)efi_pgd, PGD_ALLOCATION_ORDER);
+	free_pages((unsigned long)efi_pgd, pgd_allocation_order());
 fail:
 	return -ENOMEM;
 }

tools/arch/x86/lib/x86-opcode-map.txt

@@ -996,8 +996,8 @@ AVXcode: 4
 83: Grp1 Ev,Ib (1A),(es)
 # CTESTSCC instructions are: CTESTB, CTESTBE, CTESTF, CTESTL, CTESTLE, CTESTNB, CTESTNBE, CTESTNL,
 #			     CTESTNLE, CTESTNO, CTESTNS, CTESTNZ, CTESTO, CTESTS, CTESTT, CTESTZ
-84: CTESTSCC (ev)
-85: CTESTSCC (es) | CTESTSCC (66),(es)
+84: CTESTSCC Eb,Gb (ev)
+85: CTESTSCC Ev,Gv (es) | CTESTSCC Ev,Gv (66),(es)
 88: POPCNT Gv,Ev (es) | POPCNT Gv,Ev (66),(es)
 8f: POP2 Bq,Rq (000),(11B),(ev)
 a5: SHLD Ev,Gv,CL (es) | SHLD Ev,Gv,CL (66),(es)