Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux

Pull ARM fixes from Russell King:

 - Fix arch_memremap_can_ram_remap() which incorrectly passed a PFN to
   memblock_is_map_memory rather than the actual address.

 - Disallow kernel mode NEON when IRQs are disabled

   Explanation:

     "To avoid having to preserve/restore kernel mode NEON state when
      such a softirq is taken softirqs are now disabled when using the
      NEON from task context."

   should explain that it's nested kernel mode.

   In other words, softirqs from user mode are fine, because the context
   will be preserved. softirqs from kernel mode may be from a context
   that has already saved the user NEON state, and thus we would need to
   preserve the NEON state for the parent kernel mode context, and this
   we don't allow.

   The problem occurs when the kernel context disables hard IRQs, and
   then uses NEON. When it's finished, and restores the userspace NEON
   state, we call local_bh_enable() with hard IRQs disabled, which
   causes a warning.

   This commit addresses that by disallowing the use of NEON with hard
   IRQs disabled.

	https://lore.kernel.org/all/20250516231858.27899-4-ebiggers@kernel.org/T/#m104841b6e9346b1814c8b0fb9f2340551b0cd3e8

   has some further context

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux:
  ARM: 9446/1: Disallow kernel mode NEON when IRQs are disabled
  ARM: 9447/1: arm/memremap: fix arch_memremap_can_ram_remap()

3 files changed, 4 insertions, 4 deletions

diff --git a/arch/arm/include/asm/simd.h b/arch/arm/include/asm/simd.h
index d37559762180..be08a8da046f 100644
--- a/arch/arm/include/asm/simd.h
+++ b/arch/arm/include/asm/simd.h
@@ -8,7 +8,8 @@
 
 static __must_check inline bool may_use_simd(void)
 {
-	return IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && !in_hardirq();
+	return IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && !in_hardirq()
+	       && !irqs_disabled();
 }
 
 #endif	/* _ASM_SIMD_H */
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 748698e91a4b..27e64f782cb3 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -515,7 +515,5 @@ void __init early_ioremap_init(void)
 bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
 				 unsigned long flags)
 {
-	unsigned long pfn = PHYS_PFN(offset);
-
-	return memblock_is_map_memory(pfn);
+	return memblock_is_map_memory(offset);
 }
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 7803d50b90f8..e559ad3cd148 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -877,6 +877,7 @@ void kernel_neon_begin(void)
 	 * the kernel mode NEON register contents never need to be preserved.
 	 */
 	BUG_ON(in_hardirq());
+	BUG_ON(irqs_disabled());
 	cpu = __smp_processor_id();
 
 	fpexc = fmrx(FPEXC) | FPEXC_EN;