x86/ia32: State that IA32 emulation is disabled

Issue a short message once, on the first try to load a 32-bit process to
save people time when wondering why it won't load and trying to execute
it, would say:

  -bash: ./strsep32: cannot execute binary file: Exec format error

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: https://lore.kernel.org/r/20231130155213.1407-1-bp@alien8.de

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index a0234dfd103176518fcc7d4f372723ee080b3962..1e16bd5ac781d8ad734110278d6a47517b685f87 100644 (file)
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -150,7 +150,7 @@ do {                                                \
        ((x)->e_machine == EM_X86_64)
 
 #define compat_elf_check_arch(x)                                       \
-       ((elf_check_arch_ia32(x) && ia32_enabled()) ||                  \
+       ((elf_check_arch_ia32(x) && ia32_enabled_verbose()) ||          \
         (IS_ENABLED(CONFIG_X86_X32_ABI) && (x)->e_machine == EM_X86_64))
 
 static inline void elf_common_init(struct thread_struct *t,

diff --git a/arch/x86/include/asm/ia32.h b/arch/x86/include/asm/ia32.h
index 5a2ae24b1204f932e15ff3d5f08232e541e54be5..094886a8717eedb1b94b75a04cde89ade706e84a 100644 (file)
--- a/arch/x86/include/asm/ia32.h
+++ b/arch/x86/include/asm/ia32.h
@@ -2,7 +2,6 @@
 #ifndef _ASM_X86_IA32_H
 #define _ASM_X86_IA32_H
 
-
 #ifdef CONFIG_IA32_EMULATION
 
 #include <linux/compat.h>
@@ -84,4 +83,14 @@ static inline bool ia32_enabled(void)
 
 #endif
 
+static inline bool ia32_enabled_verbose(void)
+{
+       bool enabled = ia32_enabled();
+
+       if (IS_ENABLED(CONFIG_IA32_EMULATION) && !enabled)
+               pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
+
+       return enabled;
+}
+
 #endif /* _ASM_X86_IA32_H */