x86/iopl: Make 'struct tss_struct' constant size again

After the following commit:

  c751fe45e7f2: ("x86/pti/32: Calculate the various PTI cpu_entry_area sizes correctly, make the CPU_ENTRY_AREA_PAGES assert precise")

'struct cpu_entry_area' has to be Kconfig invariant, so that we always
have a matching CPU_ENTRY_AREA_PAGES size.

This commit added a CONFIG_X86_IOPL_IOPERM dependency to tss_struct:

  b19ba9714815: ("x86/ioperm: Extend IOPL config to control ioperm() as well")

Which, if CONFIG_X86_IOPL_IOPERM is turned off, reduces the size of
cpu_entry_area by two pages, triggering the assert:

  ./include/linux/compiler.h:391:38: error: call to ‘__compiletime_assert_202’ declared with attribute error: BUILD_BUG_ON failed: (CPU_ENTRY_AREA_PAGES+1)*PAGE_SIZE != CPU_ENTRY_AREA_MAP_SIZE

Simplify the Kconfig dependencies and make cpu_entry_area constant
size on 32-bit kernels again.

Fixes: c751fe45e7f2: ("x86/pti/32: Calculate the various PTI cpu_entry_area sizes correctly, make the CPU_ENTRY_AREA_PAGES assert precise")
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index b4e29d8b9e5a0a47631a6ff4572691255eea83bb..e51afbb0cbfbe1aab03f5db3d4b5fcd97f9dcf3b 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -411,9 +411,7 @@ struct tss_struct {
         */
        struct x86_hw_tss       x86_tss;
 
-#ifdef CONFIG_X86_IOPL_IOPERM
        struct x86_io_bitmap    io_bitmap;
-#endif
 } __aligned(PAGE_SIZE);
 
 DECLARE_PER_CPU_PAGE_ALIGNED(struct tss_struct, cpu_tss_rw);