* Re: [PATCH] x86/ia32: State that IA32 emulation is disabled
2023-11-30 15:52 [PATCH] x86/ia32: State that IA32 emulation is disabled Borislav Petkov
@ 2023-11-30 15:59 ` Nikolay Borisov
2023-11-30 16:00 ` Nikolay Borisov
` (3 subsequent siblings)
4 siblings, 0 replies; 13+ messages in thread
From: Nikolay Borisov @ 2023-11-30 15:59 UTC (permalink / raw)
To: Borislav Petkov, X86 ML; +Cc: LKML
On 30.11.23 г. 17:52 ч., Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
>
> 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 says:
>
> -bash: ./strsep32: cannot execute binary file: Exec format error
>
> No functional changes.
>
> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
> Cc: Nikolay Borisov <nik.borisov@suse.com>
LGTM:
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Would have liked for this function to replace the non-verbose variant
but since it's used in syscall it might be easier to miss.
> ---
> arch/x86/include/asm/elf.h | 2 +-
> arch/x86/include/asm/ia32.h | 9 ++++++++-
> 2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
> index a0234dfd1031..1e16bd5ac781 100644
> --- 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 5a2ae24b1204..43e02b52ad19 100644
> --- 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 +83,12 @@ static inline bool ia32_enabled(void)
>
> #endif
>
> +static inline bool ia32_enabled_verbose(void)
> +{
> +#ifdef CONFIG_IA32_EMULATION
> + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> +#endif
> + return ia32_enabled();
> +}
> +
> #endif /* _ASM_X86_IA32_H */
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH] x86/ia32: State that IA32 emulation is disabled
2023-11-30 15:52 [PATCH] x86/ia32: State that IA32 emulation is disabled Borislav Petkov
2023-11-30 15:59 ` Nikolay Borisov
@ 2023-11-30 16:00 ` Nikolay Borisov
2023-11-30 16:03 ` Borislav Petkov
2023-11-30 16:04 ` Nikolay Borisov
` (2 subsequent siblings)
4 siblings, 1 reply; 13+ messages in thread
From: Nikolay Borisov @ 2023-11-30 16:00 UTC (permalink / raw)
To: Borislav Petkov, X86 ML; +Cc: LKML
On 30.11.23 г. 17:52 ч., Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
>
> 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 says:
>
> -bash: ./strsep32: cannot execute binary file: Exec format error
>
> No functional changes.
>
> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
> Cc: Nikolay Borisov <nik.borisov@suse.com>
> ---
> arch/x86/include/asm/elf.h | 2 +-
> arch/x86/include/asm/ia32.h | 9 ++++++++-
> 2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
> index a0234dfd1031..1e16bd5ac781 100644
> --- 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 5a2ae24b1204..43e02b52ad19 100644
> --- 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 +83,12 @@ static inline bool ia32_enabled(void)
>
> #endif
>
> +static inline bool ia32_enabled_verbose(void)
> +{
> +#ifdef CONFIG_IA32_EMULATION
Hang on, this is wrong, it should be CONFIG_IA32_EMULATION_DEFAULT_DISABLED
> + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> +#endif
> + return ia32_enabled();
> +}
> +
> #endif /* _ASM_X86_IA32_H */
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH] x86/ia32: State that IA32 emulation is disabled
2023-11-30 15:52 [PATCH] x86/ia32: State that IA32 emulation is disabled Borislav Petkov
2023-11-30 15:59 ` Nikolay Borisov
2023-11-30 16:00 ` Nikolay Borisov
@ 2023-11-30 16:04 ` Nikolay Borisov
2023-11-30 16:09 ` Borislav Petkov
2023-12-11 9:28 ` [tip: x86/misc] " tip-bot2 for Borislav Petkov (AMD)
4 siblings, 0 replies; 13+ messages in thread
From: Nikolay Borisov @ 2023-11-30 16:04 UTC (permalink / raw)
To: Borislav Petkov, X86 ML; +Cc: LKML
On 30.11.23 г. 17:52 ч., Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
>
> 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 says:
>
> -bash: ./strsep32: cannot execute binary file: Exec format error
>
> No functional changes.
>
> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
> Cc: Nikolay Borisov <nik.borisov@suse.com>
> ---
> arch/x86/include/asm/elf.h | 2 +-
> arch/x86/include/asm/ia32.h | 9 ++++++++-
> 2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
> index a0234dfd1031..1e16bd5ac781 100644
> --- 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 5a2ae24b1204..43e02b52ad19 100644
> --- 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 +83,12 @@ static inline bool ia32_enabled(void)
>
> #endif
>
> +static inline bool ia32_enabled_verbose(void)
> +{
> +#ifdef CONFIG_IA32_EMULATION
> + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
Actually this will result in a false-positive, even with the
DEFAULT_DISABLED but booting with ia32_emulation = 0 so it's best if
it's predicated on the output of ia32_enabled. This means we'll always
pay the price of the branch even if it's disabled but removes a spurious
notice in a certain case.
> +#endif
> + return ia32_enabled();
> +}
> +
> #endif /* _ASM_X86_IA32_H */
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH] x86/ia32: State that IA32 emulation is disabled
2023-11-30 15:52 [PATCH] x86/ia32: State that IA32 emulation is disabled Borislav Petkov
` (2 preceding siblings ...)
2023-11-30 16:04 ` Nikolay Borisov
@ 2023-11-30 16:09 ` Borislav Petkov
2023-11-30 16:42 ` Brian Gerst
2023-12-06 17:20 ` [PATCH -v2] " Borislav Petkov
2023-12-11 9:28 ` [tip: x86/misc] " tip-bot2 for Borislav Petkov (AMD)
4 siblings, 2 replies; 13+ messages in thread
From: Borislav Petkov @ 2023-11-30 16:09 UTC (permalink / raw)
To: X86 ML; +Cc: LKML, Nikolay Borisov
On Thu, Nov 30, 2023 at 04:52:13PM +0100, Borislav Petkov wrote:
> +static inline bool ia32_enabled_verbose(void)
> +{
> +#ifdef CONFIG_IA32_EMULATION
> + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> +#endif
> + return ia32_enabled();
> +}
As Nik rightfully points out offlist, this should rather be something
like:
---
bool enabled = ia32_enabled();
#ifdef CONFIG_IA32_EMULATION
if (!enabled)
pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
#endif
return enabled;
---
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH] x86/ia32: State that IA32 emulation is disabled
2023-11-30 16:09 ` Borislav Petkov
@ 2023-11-30 16:42 ` Brian Gerst
2023-11-30 16:47 ` Brian Gerst
2023-12-06 17:20 ` [PATCH -v2] " Borislav Petkov
1 sibling, 1 reply; 13+ messages in thread
From: Brian Gerst @ 2023-11-30 16:42 UTC (permalink / raw)
To: Borislav Petkov; +Cc: X86 ML, LKML, Nikolay Borisov
On Thu, Nov 30, 2023 at 11:09 AM Borislav Petkov <bp@alien8.de> wrote:
>
> On Thu, Nov 30, 2023 at 04:52:13PM +0100, Borislav Petkov wrote:
> > +static inline bool ia32_enabled_verbose(void)
> > +{
> > +#ifdef CONFIG_IA32_EMULATION
> > + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> > +#endif
> > + return ia32_enabled();
> > +}
>
> As Nik rightfully points out offlist, this should rather be something
> like:
>
> ---
> bool enabled = ia32_enabled();
>
> #ifdef CONFIG_IA32_EMULATION
> if (!enabled)
> pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> #endif
>
> return enabled;
The #ifdef isn't necessary, as ia32_enabled() will always return false
in that case.
Brian Gerst
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH] x86/ia32: State that IA32 emulation is disabled
2023-11-30 16:42 ` Brian Gerst
@ 2023-11-30 16:47 ` Brian Gerst
0 siblings, 0 replies; 13+ messages in thread
From: Brian Gerst @ 2023-11-30 16:47 UTC (permalink / raw)
To: Borislav Petkov; +Cc: X86 ML, LKML, Nikolay Borisov
On Thu, Nov 30, 2023 at 11:42 AM Brian Gerst <brgerst@gmail.com> wrote:
>
> On Thu, Nov 30, 2023 at 11:09 AM Borislav Petkov <bp@alien8.de> wrote:
> >
> > On Thu, Nov 30, 2023 at 04:52:13PM +0100, Borislav Petkov wrote:
> > > +static inline bool ia32_enabled_verbose(void)
> > > +{
> > > +#ifdef CONFIG_IA32_EMULATION
> > > + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> > > +#endif
> > > + return ia32_enabled();
> > > +}
> >
> > As Nik rightfully points out offlist, this should rather be something
> > like:
> >
> > ---
> > bool enabled = ia32_enabled();
> >
> > #ifdef CONFIG_IA32_EMULATION
> > if (!enabled)
> > pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> > #endif
> >
> > return enabled;
>
> The #ifdef isn't necessary, as ia32_enabled() will always return false
> in that case.
Scratch that, I misread it. If compat is disabled at build time you
don't want the message to appear, or at least would want a different
message.
Brian Gerst
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH -v2] x86/ia32: State that IA32 emulation is disabled
2023-11-30 16:09 ` Borislav Petkov
2023-11-30 16:42 ` Brian Gerst
@ 2023-12-06 17:20 ` Borislav Petkov
2023-12-08 18:42 ` Nikolay Borisov
1 sibling, 1 reply; 13+ messages in thread
From: Borislav Petkov @ 2023-12-06 17:20 UTC (permalink / raw)
To: X86 ML; +Cc: LKML, Nikolay Borisov
From: "Borislav Petkov (AMD)" <bp@alien8.de>
Date: Thu, 30 Nov 2023 16:39:33 +0100
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>
Cc: Nikolay Borisov <nik.borisov@suse.com>
---
arch/x86/include/asm/elf.h | 2 +-
arch/x86/include/asm/ia32.h | 11 ++++++++++-
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index a0234dfd1031..1e16bd5ac781 100644
--- 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 5a2ae24b1204..094886a8717e 100644
--- 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 */
--
2.42.0.rc0.25.ga82fb66fed25
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH -v2] x86/ia32: State that IA32 emulation is disabled
2023-12-06 17:20 ` [PATCH -v2] " Borislav Petkov
@ 2023-12-08 18:42 ` Nikolay Borisov
2023-12-08 19:22 ` Borislav Petkov
0 siblings, 1 reply; 13+ messages in thread
From: Nikolay Borisov @ 2023-12-08 18:42 UTC (permalink / raw)
To: Borislav Petkov, X86 ML; +Cc: LKML
On 6.12.23 г. 19:20 ч., Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
> Date: Thu, 30 Nov 2023 16:39:33 +0100
>
> 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>
> Cc: Nikolay Borisov <nik.borisov@suse.com>
LGTM:
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
> ---
> arch/x86/include/asm/elf.h | 2 +-
> arch/x86/include/asm/ia32.h | 11 ++++++++++-
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
> index a0234dfd1031..1e16bd5ac781 100644
> --- 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 5a2ae24b1204..094886a8717e 100644
> --- 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)
nit: But why check config_ia32_emulation explicitly, its state should
already be accounted for in ia32_enabled's value? So this check can
simply be 'if (!enabled)'
> + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> +
> + return enabled;
> +}
> +
> #endif /* _ASM_X86_IA32_H */
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH -v2] x86/ia32: State that IA32 emulation is disabled
2023-12-08 18:42 ` Nikolay Borisov
@ 2023-12-08 19:22 ` Borislav Petkov
2023-12-08 19:28 ` Nikolay Borisov
0 siblings, 1 reply; 13+ messages in thread
From: Borislav Petkov @ 2023-12-08 19:22 UTC (permalink / raw)
To: Nikolay Borisov; +Cc: X86 ML, LKML
On Fri, Dec 08, 2023 at 08:42:29PM +0200, Nikolay Borisov wrote:
> > +static inline bool ia32_enabled_verbose(void)
> > +{
> > + bool enabled = ia32_enabled();
> > +
> > + if (IS_ENABLED(CONFIG_IA32_EMULATION) && !enabled)
>
> nit: But why check config_ia32_emulation explicitly, its state should
> already be accounted for in ia32_enabled's value? So this check can simply
> be 'if (!enabled)'
>
> > + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
^^^^^^^^^^
If CONFIG_IA32_EMULATION is disabled, is there any 32-bit emulation to
be enabled, at all?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH -v2] x86/ia32: State that IA32 emulation is disabled
2023-12-08 19:22 ` Borislav Petkov
@ 2023-12-08 19:28 ` Nikolay Borisov
0 siblings, 0 replies; 13+ messages in thread
From: Nikolay Borisov @ 2023-12-08 19:28 UTC (permalink / raw)
To: Borislav Petkov; +Cc: X86 ML, LKML
On 8.12.23 г. 21:22 ч., Borislav Petkov wrote:
> On Fri, Dec 08, 2023 at 08:42:29PM +0200, Nikolay Borisov wrote:
>>> +static inline bool ia32_enabled_verbose(void)
>>> +{
>>> + bool enabled = ia32_enabled();
>>> +
>>> + if (IS_ENABLED(CONFIG_IA32_EMULATION) && !enabled)
>>
>> nit: But why check config_ia32_emulation explicitly, its state should
>> already be accounted for in ia32_enabled's value? So this check can simply
>> be 'if (!enabled)'
>>
>>> + pr_notice_once("32-bit emulation disabled. You can reenable with ia32_emulation=on\n");
> ^^^^^^^^^^
>
> If CONFIG_IA32_EMULATION is disabled, is there any 32-bit emulation to
> be enabled, at all?
>
Ah, the !enabled condition will then trigger so it will result in a
false print. Fair enough...
^ permalink raw reply [flat|nested] 13+ messages in thread
* [tip: x86/misc] x86/ia32: State that IA32 emulation is disabled
2023-11-30 15:52 [PATCH] x86/ia32: State that IA32 emulation is disabled Borislav Petkov
` (3 preceding siblings ...)
2023-11-30 16:09 ` Borislav Petkov
@ 2023-12-11 9:28 ` tip-bot2 for Borislav Petkov (AMD)
4 siblings, 0 replies; 13+ messages in thread
From: tip-bot2 for Borislav Petkov (AMD) @ 2023-12-11 9:28 UTC (permalink / raw)
To: linux-tip-commits
Cc: Borislav Petkov (AMD), Nikolay Borisov, x86, linux-kernel
The following commit has been merged into the x86/misc branch of tip:
Commit-ID: f789383fa34a266d0c1a76f272043a15a8edf733
Gitweb: https://git.kernel.org/tip/f789383fa34a266d0c1a76f272043a15a8edf733
Author: Borislav Petkov (AMD) <bp@alien8.de>
AuthorDate: Thu, 30 Nov 2023 16:39:33 +01:00
Committer: Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 11 Dec 2023 10:14:28 +01:00
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
---
arch/x86/include/asm/elf.h | 2 +-
arch/x86/include/asm/ia32.h | 11 ++++++++++-
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index a0234df..1e16bd5 100644
--- 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 5a2ae24..094886a 100644
--- 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 */
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