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[PATCH] x86/its: Fix build errors when CONFIG_MODULES=n

Eric Biggers posted 1 patch 9 months ago 
arch/x86/kernel/alternative.c | 6 ++++++
1 file changed, 6 insertions(+)
[PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Eric Biggers 9 months ago 
From: Eric Biggers <ebiggers@google.com>

Fix several build errors when CONFIG_MODULES=n, including the following:

../arch/x86/kernel/alternative.c:195:25: error: incomplete definition of type 'struct module'
  195 |         for (int i = 0; i < mod->its_num_pages; i++) {

Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 arch/x86/kernel/alternative.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 48fd04e90114..45bcff181cba 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -131,11 +131,13 @@ const unsigned char * const x86_nops[ASM_NOP_MAX+1] =
 static bool cfi_paranoid __ro_after_init;
 #endif
 
 #ifdef CONFIG_MITIGATION_ITS
 
+#ifdef CONFIG_MODULES
 static struct module *its_mod;
+#endif
 static void *its_page;
 static unsigned int its_offset;
 
 /* Initialize a thunk with the "jmp *reg; int3" instructions. */
 static void *its_init_thunk(void *thunk, int reg)
@@ -169,10 +171,11 @@ static void *its_init_thunk(void *thunk, int reg)
 	bytes[i++] = 0xcc;
 
 	return thunk + offset;
 }
 
+#ifdef CONFIG_MODULES
 void its_init_mod(struct module *mod)
 {
 	if (!cpu_feature_enabled(X86_FEATURE_INDIRECT_THUNK_ITS))
 		return;
 
@@ -207,18 +210,20 @@ void its_free_mod(struct module *mod)
 		void *page = mod->its_page_array[i];
 		execmem_free(page);
 	}
 	kfree(mod->its_page_array);
 }
+#endif /* CONFIG_MODULES */
 
 static void *its_alloc(void)
 {
 	void *page __free(execmem) = execmem_alloc(EXECMEM_MODULE_TEXT, PAGE_SIZE);
 
 	if (!page)
 		return NULL;
 
+#ifdef CONFIG_MODULES
 	if (its_mod) {
 		void *tmp = krealloc(its_mod->its_page_array,
 				     (its_mod->its_num_pages+1) * sizeof(void *),
 				     GFP_KERNEL);
 		if (!tmp)
@@ -227,10 +232,11 @@ static void *its_alloc(void)
 		its_mod->its_page_array = tmp;
 		its_mod->its_page_array[its_mod->its_num_pages++] = page;
 
 		execmem_make_temp_rw(page, PAGE_SIZE);
 	}
+#endif /* CONFIG_MODULES */
 
 	return no_free_ptr(page);
 }
 
 static void *its_allocate_thunk(int reg)

base-commit: 627277ba7c2398dc4f95cc9be8222bb2d9477800
-- 
2.49.0
Re: [PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Dave Hansen 8 months, 4 weeks ago 
On 5/12/25 19:58, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Fix several build errors when CONFIG_MODULES=n, including the following:
> 
> ../arch/x86/kernel/alternative.c:195:25: error: incomplete definition of type 'struct module'
>   195 |         for (int i = 0; i < mod->its_num_pages; i++) {

Thanks for sending this:

Acked-by: Dave Hansen <dave.hansen@intel.com>
Re: [PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Dave Hansen 8 months, 4 weeks ago 
On 5/13/25 11:54, Dave Hansen wrote:
> On 5/12/25 19:58, Eric Biggers wrote:
>> From: Eric Biggers <ebiggers@google.com>
>>
>> Fix several build errors when CONFIG_MODULES=n, including the following:
>>
>> ../arch/x86/kernel/alternative.c:195:25: error: incomplete definition of type 'struct module'
>>   195 |         for (int i = 0; i < mod->its_num_pages; i++) {

Linus, could you pick this one up directly, please? The thread has acks
from a few folks already.

The normal x86/urgent branch doesn't have this bug yet and I don't want
to merge the existing pile of fixes with your tree at a completely
random point.

Oh, and you called it ... "done without public testing" strikes again.
Re: [PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Linus Torvalds 8 months, 4 weeks ago 
On Tue, 13 May 2025 at 13:32, Dave Hansen <dave.hansen@intel.com> wrote:
>
> Linus, could you pick this one up directly, please?

Done. Thanks,

                 Linus
Re: [PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Steven Rostedt 8 months, 4 weeks ago 
On Mon, 12 May 2025 19:58:39 -0700
Eric Biggers <ebiggers@kernel.org> wrote:

> Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches")
> Cc: stable@vger.kernel.org

No need to Cc stable. This isn't even in Linus's tree.

-- Steve

> Signed-off-by: Eric Biggers <ebiggers@google.com>
Re: [PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Harshit Mogalapalli 8 months, 4 weeks ago 
Hi Steven,


On 13/05/25 23:47, Steven Rostedt wrote:
> On Mon, 12 May 2025 19:58:39 -0700
> Eric Biggers <ebiggers@kernel.org> wrote:
> 
>> Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches")
>> Cc: stable@vger.kernel.org
> 
> No need to Cc stable. This isn't even in Linus's tree.

It is now(today) present I think: 
https://github.com/torvalds/linux/commit/872df34d7c51a79523820ea6a14860398c639b87

Greg queued this up for today's stable-rc which was released for Testing.

Informed him about this fix:

https://lore.kernel.org/all/88d537d6-57be-4fbc-9722-15997a022abb@oracle.com/

Thanks,
Harshit


> -- Steve
> 
>> Signed-off-by: Eric Biggers <ebiggers@google.com>
>
Re: [PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Steven Rostedt 8 months, 4 weeks ago 
On Wed, 14 May 2025 00:53:26 +0530
Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> wrote:

> Hi Steven,
> 
> 
> On 13/05/25 23:47, Steven Rostedt wrote:
> > On Mon, 12 May 2025 19:58:39 -0700
> > Eric Biggers <ebiggers@kernel.org> wrote:
> >   
> >> Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches")
> >> Cc: stable@vger.kernel.org  
> > 
> > No need to Cc stable. This isn't even in Linus's tree.  
> 
> It is now(today) present I think: 
> https://github.com/torvalds/linux/commit/872df34d7c51a79523820ea6a14860398c639b87

Bah. My upstream repo gets updated every night via a cronjob, and that's
what I was looking at.

> 
> Greg queued this up for today's stable-rc which was released for Testing.

I didn't see any "stable" or "fixes" tag in the offending commit, so I
definitely didn't expect it to be in stable :-p


> 
> Informed him about this fix:
> 
> https://lore.kernel.org/all/88d537d6-57be-4fbc-9722-15997a022abb@oracle.com/

Thanks for letting me know.

-- Steve
Re: [PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Steven Rostedt 8 months, 4 weeks ago 
On Mon, 12 May 2025 19:58:39 -0700
Eric Biggers <ebiggers@kernel.org> wrote:

> From: Eric Biggers <ebiggers@google.com>
> 
> Fix several build errors when CONFIG_MODULES=n, including the following:
> 
> ../arch/x86/kernel/alternative.c:195:25: error: incomplete definition of type 'struct module'
>   195 |         for (int i = 0; i < mod->its_num_pages; i++) {
> 
> Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches")
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---

I just hit this build failure while running tests on patches that are on
top of tip/master.

Tested-by: Steven Rostedt (Google) <rostedt@goodmis.org>

-- Steve
Re: [PATCH] x86/its: Fix build errors when CONFIG_MODULES=n
Posted by Alexandre Chartre 8 months, 4 weeks ago 
On 5/13/25 04:58, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Fix several build errors when CONFIG_MODULES=n, including the following:
> 
> ../arch/x86/kernel/alternative.c:195:25: error: incomplete definition of type 'struct module'
>    195 |         for (int i = 0; i < mod->its_num_pages; i++) {
> 
> Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches")
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>   arch/x86/kernel/alternative.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 

Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>

alex.

> diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
> index 48fd04e90114..45bcff181cba 100644
> --- a/arch/x86/kernel/alternative.c
> +++ b/arch/x86/kernel/alternative.c
> @@ -131,11 +131,13 @@ const unsigned char * const x86_nops[ASM_NOP_MAX+1] =
>   static bool cfi_paranoid __ro_after_init;
>   #endif
>   
>   #ifdef CONFIG_MITIGATION_ITS
>   
> +#ifdef CONFIG_MODULES
>   static struct module *its_mod;
> +#endif
>   static void *its_page;
>   static unsigned int its_offset;
>   
>   /* Initialize a thunk with the "jmp *reg; int3" instructions. */
>   static void *its_init_thunk(void *thunk, int reg)
> @@ -169,10 +171,11 @@ static void *its_init_thunk(void *thunk, int reg)
>   	bytes[i++] = 0xcc;
>   
>   	return thunk + offset;
>   }
>   
> +#ifdef CONFIG_MODULES
>   void its_init_mod(struct module *mod)
>   {
>   	if (!cpu_feature_enabled(X86_FEATURE_INDIRECT_THUNK_ITS))
>   		return;
>   
> @@ -207,18 +210,20 @@ void its_free_mod(struct module *mod)
>   		void *page = mod->its_page_array[i];
>   		execmem_free(page);
>   	}
>   	kfree(mod->its_page_array);
>   }
> +#endif /* CONFIG_MODULES */
>   
>   static void *its_alloc(void)
>   {
>   	void *page __free(execmem) = execmem_alloc(EXECMEM_MODULE_TEXT, PAGE_SIZE);
>   
>   	if (!page)
>   		return NULL;
>   
> +#ifdef CONFIG_MODULES
>   	if (its_mod) {
>   		void *tmp = krealloc(its_mod->its_page_array,
>   				     (its_mod->its_num_pages+1) * sizeof(void *),
>   				     GFP_KERNEL);
>   		if (!tmp)
> @@ -227,10 +232,11 @@ static void *its_alloc(void)
>   		its_mod->its_page_array = tmp;
>   		its_mod->its_page_array[its_mod->its_num_pages++] = page;
>   
>   		execmem_make_temp_rw(page, PAGE_SIZE);
>   	}
> +#endif /* CONFIG_MODULES */
>   
>   	return no_free_ptr(page);
>   }
>   
>   static void *its_allocate_thunk(int reg)
> 
> base-commit: 627277ba7c2398dc4f95cc9be8222bb2d9477800

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