diff mbox

arm64: ftrace: fix building without CONFIG_MODULES

Message ID 20170609102807.2992510-1-arnd@arndb.de
State New
Headers show

Commit Message

Arnd Bergmann June 9, 2017, 10:27 a.m. UTC 
When CONFIG_MODULES is disabled, we cannot dereference a module pointer:

arch/arm64/kernel/ftrace.c: In function 'ftrace_make_call':
arch/arm64/kernel/ftrace.c:107:36: error: dereferencing pointer to incomplete type 'struct module'
   trampoline = (unsigned long *)mod->arch.ftrace_trampoline;

Also, the within_module() function is not defined:

arch/arm64/kernel/ftrace.c: In function 'ftrace_make_nop':
arch/arm64/kernel/ftrace.c:171:8: error: implicit declaration of function 'within_module'; did you mean 'init_module'? [-Werror=implicit-function-declaration]

This addresses both by adding the appropriate stubs.

Fixes: e71a4e1bebaf ("arm64: ftrace: add support for far branches to dynamic ftrace")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 arch/arm64/include/asm/module.h | 6 ++++++
 arch/arm64/kernel/ftrace.c      | 2 +-
 include/linux/module.h          | 5 +++++
 3 files changed, 12 insertions(+), 1 deletion(-)

-- 
2.9.0

Comments

Will Deacon June 9, 2017, 11:38 a.m. UTC | #1 
Hi Arnd,

On Fri, Jun 09, 2017 at 12:27:06PM +0200, Arnd Bergmann wrote:
> When CONFIG_MODULES is disabled, we cannot dereference a module pointer:

> 

> arch/arm64/kernel/ftrace.c: In function 'ftrace_make_call':

> arch/arm64/kernel/ftrace.c:107:36: error: dereferencing pointer to incomplete type 'struct module'

>    trampoline = (unsigned long *)mod->arch.ftrace_trampoline;

> 

> Also, the within_module() function is not defined:

> 

> arch/arm64/kernel/ftrace.c: In function 'ftrace_make_nop':

> arch/arm64/kernel/ftrace.c:171:8: error: implicit declaration of function 'within_module'; did you mean 'init_module'? [-Werror=implicit-function-declaration]

> 

> This addresses both by adding the appropriate stubs.

> 

> Fixes: e71a4e1bebaf ("arm64: ftrace: add support for far branches to dynamic ftrace")

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

>  arch/arm64/include/asm/module.h | 6 ++++++

>  arch/arm64/kernel/ftrace.c      | 2 +-

>  include/linux/module.h          | 5 +++++

>  3 files changed, 12 insertions(+), 1 deletion(-)


I can't seem to reproduce this simply by disabling MODULES in defconfig.
Could you share your .config, please?

Will
Arnd Bergmann June 9, 2017, 6:57 p.m. UTC | #2 
On Fri, Jun 9, 2017 at 1:38 PM, Will Deacon <will.deacon@arm.com> wrote:
> Hi Arnd,

>

> On Fri, Jun 09, 2017 at 12:27:06PM +0200, Arnd Bergmann wrote:

>> When CONFIG_MODULES is disabled, we cannot dereference a module pointer:

>>

>> arch/arm64/kernel/ftrace.c: In function 'ftrace_make_call':

>> arch/arm64/kernel/ftrace.c:107:36: error: dereferencing pointer to incomplete type 'struct module'

>>    trampoline = (unsigned long *)mod->arch.ftrace_trampoline;

>>

>> Also, the within_module() function is not defined:

>>

>> arch/arm64/kernel/ftrace.c: In function 'ftrace_make_nop':

>> arch/arm64/kernel/ftrace.c:171:8: error: implicit declaration of function 'within_module'; did you mean 'init_module'? [-Werror=implicit-function-declaration]

>>

>> This addresses both by adding the appropriate stubs.

>>

>> Fixes: e71a4e1bebaf ("arm64: ftrace: add support for far branches to dynamic ftrace")

>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

>> ---

>>  arch/arm64/include/asm/module.h | 6 ++++++

>>  arch/arm64/kernel/ftrace.c      | 2 +-

>>  include/linux/module.h          | 5 +++++

>>  3 files changed, 12 insertions(+), 1 deletion(-)

>

> I can't seem to reproduce this simply by disabling MODULES in defconfig.

> Could you share your .config, please?


This is the randconfig I used: https://pastebin.com/SfKBY7f8

      Arnd
Will Deacon June 12, 2017, 12:48 p.m. UTC | #3 
On Fri, Jun 09, 2017 at 08:57:31PM +0200, Arnd Bergmann wrote:
> On Fri, Jun 9, 2017 at 1:38 PM, Will Deacon <will.deacon@arm.com> wrote:

> > On Fri, Jun 09, 2017 at 12:27:06PM +0200, Arnd Bergmann wrote:

> >> When CONFIG_MODULES is disabled, we cannot dereference a module pointer:

> >>

> >> arch/arm64/kernel/ftrace.c: In function 'ftrace_make_call':

> >> arch/arm64/kernel/ftrace.c:107:36: error: dereferencing pointer to incomplete type 'struct module'

> >>    trampoline = (unsigned long *)mod->arch.ftrace_trampoline;

> >>

> >> Also, the within_module() function is not defined:

> >>

> >> arch/arm64/kernel/ftrace.c: In function 'ftrace_make_nop':

> >> arch/arm64/kernel/ftrace.c:171:8: error: implicit declaration of function 'within_module'; did you mean 'init_module'? [-Werror=implicit-function-declaration]

> >>

> >> This addresses both by adding the appropriate stubs.

> >>

> >> Fixes: e71a4e1bebaf ("arm64: ftrace: add support for far branches to dynamic ftrace")

> >> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> >> ---

> >>  arch/arm64/include/asm/module.h | 6 ++++++

> >>  arch/arm64/kernel/ftrace.c      | 2 +-

> >>  include/linux/module.h          | 5 +++++

> >>  3 files changed, 12 insertions(+), 1 deletion(-)

> >

> > I can't seem to reproduce this simply by disabling MODULES in defconfig.

> > Could you share your .config, please?

> 

> This is the randconfig I used: https://pastebin.com/SfKBY7f8


Thanks, I was forgetting to enable ftrace. I think a simpler patch (and one
that I can just apply via arm64) is switching the IS_ENABLEDs out for
#ifdefs. See below.

Will

--->8diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 8a42be0693c9..401aa27808a4 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -71,11 +71,12 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
 	unsigned long pc = rec->ip;
-	long offset = (long)pc - (long)addr;
 	u32 old, new;
 
-	if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
-	    (offset < -SZ_128M || offset >= SZ_128M)) {
+#ifdef CONFIG_ARM64_MODULE_PLTS
+	long offset = (long)pc - (long)addr;
+
+	if (offset < -SZ_128M || offset >= SZ_128M) {
 		unsigned long *trampoline;
 		struct module *mod;
 
@@ -121,6 +122,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 		}
 		addr = (unsigned long)&trampoline[1];
 	}
+#endif /* CONFIG_ARM64_MODULE_PLTS */
 
 	old = aarch64_insn_gen_nop();
 	new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
@@ -135,12 +137,13 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 		    unsigned long addr)
 {
 	unsigned long pc = rec->ip;
-	long offset = (long)pc - (long)addr;
 	bool validate = true;
 	u32 old = 0, new;
 
-	if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
-	    (offset < -SZ_128M || offset >= SZ_128M)) {
+#ifdef CONFIG_ARM64_MODULE_PLTS
+	long offset = (long)pc - (long)addr;
+
+	if (offset < -SZ_128M || offset >= SZ_128M) {
 		u32 replaced;
 
 		/*
@@ -177,6 +180,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 		old = aarch64_insn_gen_branch_imm(pc, addr,
 						  AARCH64_INSN_BRANCH_LINK);
 	}
+#endif /* CONFIG_ARM64_MODULE_PLTS */
 
 	new = aarch64_insn_gen_nop();
Ard Biesheuvel June 12, 2017, 1:01 p.m. UTC | #4 
On 12 June 2017 at 14:48, Will Deacon <will.deacon@arm.com> wrote:
> On Fri, Jun 09, 2017 at 08:57:31PM +0200, Arnd Bergmann wrote:

>> On Fri, Jun 9, 2017 at 1:38 PM, Will Deacon <will.deacon@arm.com> wrote:

>> > On Fri, Jun 09, 2017 at 12:27:06PM +0200, Arnd Bergmann wrote:

>> >> When CONFIG_MODULES is disabled, we cannot dereference a module pointer:

>> >>

>> >> arch/arm64/kernel/ftrace.c: In function 'ftrace_make_call':

>> >> arch/arm64/kernel/ftrace.c:107:36: error: dereferencing pointer to incomplete type 'struct module'

>> >>    trampoline = (unsigned long *)mod->arch.ftrace_trampoline;

>> >>

>> >> Also, the within_module() function is not defined:

>> >>

>> >> arch/arm64/kernel/ftrace.c: In function 'ftrace_make_nop':

>> >> arch/arm64/kernel/ftrace.c:171:8: error: implicit declaration of function 'within_module'; did you mean 'init_module'? [-Werror=implicit-function-declaration]

>> >>

>> >> This addresses both by adding the appropriate stubs.

>> >>

>> >> Fixes: e71a4e1bebaf ("arm64: ftrace: add support for far branches to dynamic ftrace")

>> >> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

>> >> ---

>> >>  arch/arm64/include/asm/module.h | 6 ++++++

>> >>  arch/arm64/kernel/ftrace.c      | 2 +-

>> >>  include/linux/module.h          | 5 +++++

>> >>  3 files changed, 12 insertions(+), 1 deletion(-)

>> >

>> > I can't seem to reproduce this simply by disabling MODULES in defconfig.

>> > Could you share your .config, please?

>>

>> This is the randconfig I used: https://pastebin.com/SfKBY7f8

>

> Thanks, I was forgetting to enable ftrace. I think a simpler patch (and one

> that I can just apply via arm64) is switching the IS_ENABLEDs out for

> #ifdefs.


I agree that this makes more sense in this particular case.

Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>


Interestingly, ARM64_MODULE_PLTS does not depend on CONFIG_MODULES,
but I can't remember whether that was deliberate or an oversight.

> See below.

>

> --->8

>

> diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c

> index 8a42be0693c9..401aa27808a4 100644

> --- a/arch/arm64/kernel/ftrace.c

> +++ b/arch/arm64/kernel/ftrace.c

> @@ -71,11 +71,12 @@ int ftrace_update_ftrace_func(ftrace_func_t func)

>  int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)

>  {

>         unsigned long pc = rec->ip;

> -       long offset = (long)pc - (long)addr;

>         u32 old, new;

>

> -       if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&

> -           (offset < -SZ_128M || offset >= SZ_128M)) {

> +#ifdef CONFIG_ARM64_MODULE_PLTS

> +       long offset = (long)pc - (long)addr;

> +

> +       if (offset < -SZ_128M || offset >= SZ_128M) {

>                 unsigned long *trampoline;

>                 struct module *mod;

>

> @@ -121,6 +122,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)

>                 }

>                 addr = (unsigned long)&trampoline[1];

>         }

> +#endif /* CONFIG_ARM64_MODULE_PLTS */

>

>         old = aarch64_insn_gen_nop();

>         new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);

> @@ -135,12 +137,13 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,

>                     unsigned long addr)

>  {

>         unsigned long pc = rec->ip;

> -       long offset = (long)pc - (long)addr;

>         bool validate = true;

>         u32 old = 0, new;

>

> -       if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&

> -           (offset < -SZ_128M || offset >= SZ_128M)) {

> +#ifdef CONFIG_ARM64_MODULE_PLTS

> +       long offset = (long)pc - (long)addr;

> +

> +       if (offset < -SZ_128M || offset >= SZ_128M) {

>                 u32 replaced;

>

>                 /*

> @@ -177,6 +180,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,

>                 old = aarch64_insn_gen_branch_imm(pc, addr,

>                                                   AARCH64_INSN_BRANCH_LINK);

>         }

> +#endif /* CONFIG_ARM64_MODULE_PLTS */

>

>         new = aarch64_insn_gen_nop();

>
Arnd Bergmann June 12, 2017, 2:22 p.m. UTC | #5 
On Mon, Jun 12, 2017 at 2:48 PM, Will Deacon <will.deacon@arm.com> wrote:
> On Fri, Jun 09, 2017 at 08:57:31PM +0200, Arnd Bergmann wrote:

>> On Fri, Jun 9, 2017 at 1:38 PM, Will Deacon <will.deacon@arm.com> wrote:

>> > I can't seem to reproduce this simply by disabling MODULES in defconfig.

>> > Could you share your .config, please?

>>

>> This is the randconfig I used: https://pastebin.com/SfKBY7f8

>

> Thanks, I was forgetting to enable ftrace. I think a simpler patch (and one

> that I can just apply via arm64) is switching the IS_ENABLEDs out for

> #ifdefs. See below.


Yes, good idea.

        Arnd
diff mbox

Patch

diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h
index 19bd97671bb8..ca5d024f4247 100644
--- a/arch/arm64/include/asm/module.h
+++ b/arch/arm64/include/asm/module.h
@@ -36,6 +36,12 @@  struct mod_arch_specific {
 };
 #endif
 
+#if defined(CONFIG_MODULES) && defined(CONFIG_ARM64_MODULE_PLTS)
+#define module_ftrace_trampoline(mod) ((mod)->arch.ftrace_trampoline)
+#else
+#define module_ftrace_trampoline(mod) NULL
+#endif
+
 u64 module_emit_plt_entry(struct module *mod, void *loc, const Elf64_Rela *rela,
 			  Elf64_Sym *sym);
 
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 8a42be0693c9..7f5eb9939a55 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -104,7 +104,7 @@  int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 		 * is added in the future, but for now, the pr_err() below
 		 * deals with a theoretical issue only.
 		 */
-		trampoline = (unsigned long *)mod->arch.ftrace_trampoline;
+		trampoline = module_ftrace_trampoline(mod);
 		if (trampoline[0] != addr) {
 			if (trampoline[0] != 0) {
 				pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n");
diff --git a/include/linux/module.h b/include/linux/module.h
index 21f56393602f..9196f532f158 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -671,6 +671,11 @@  static inline bool is_module_text_address(unsigned long addr)
 	return false;
 }
 
+static inline bool within_module(unsigned long addr, const struct module *mod)
+{
+	return false;
+}
+
 /* Get/put a kernel symbol (calls should be symmetric) */
 #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak)); &(x); })
 #define symbol_put(x) do { } while (0)