x86: only use lfence if x86 bcb config enabled

Work around a testcase problem, where we want to check some
logic for the bounds check bypass mitigation in the common
kernel code. By changing the ifdef to the x86-specific option
for these lfence instructions, we avoid IAMCU build errors
but still test the common code.

Signed-off-by: Andrew Boie <[email protected]>

Author: Andrew Boie

arch/x86/core/ia32/userspace.S

@@ -199,7 +199,7 @@ SECTION_FUNC(TEXT, z_x86_syscall_entry_stub)
 	jae	_bad_syscall
 
 _id_ok:
-#ifdef CONFIG_BOUNDS_CHECK_BYPASS_MITIGATION
+#ifdef CONFIG_X86_BOUNDS_CHECK_BYPASS_MITIGATION
 	/* Prevent speculation with bogus system call IDs */
 	lfence
 #endif

arch/x86/core/ia32/x86_mmu.c

@@ -162,7 +162,7 @@ int z_arch_buffer_validate(void *addr, size_t size, int write)
 	}
 	ret = 0;
 out:
-#ifdef CONFIG_BOUNDS_CHECK_BYPASS_MITIGATION
+#ifdef CONFIG_X86_BOUNDS_CHECK_BYPASS_MITIGATION
 	__asm__ volatile ("lfence" : : : "memory");
 #endif