[PATCH] um: always use the same type for __syscall_stub_start

[PATCH] um: always use the same type for __syscall_stub_start

[Nicolas Iooss]

syscall_stub_start is declared with different types in C files:

  arch/um/kernel/physmem.c: extern int __syscall_stub_start;
  arch/um/kernel/skas/mmu.c: extern int __syscall_stub_start;
  arch/um/os-Linux/skas/mem.c: extern unsigned long __syscall_stub_start;
  arch/um/os-Linux/skas/process.c: extern int __syscall_stub_start;

Fix this inconsistency by always using unsigned long.  This does not
change anything in the compiled code because only the address of
__syscall_stub_start is used, but it makes the static checker I use
stop complaining about incompatible declarations.

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
---
 arch/um/kernel/physmem.c        | 2 +-
 arch/um/kernel/skas/mmu.c       | 2 +-
 arch/um/os-Linux/skas/process.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index 30fdd5d0067b..f1d7ed26d638 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -75,7 +75,7 @@ void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
 	}
 }
 
-extern int __syscall_stub_start;
+extern unsigned long __syscall_stub_start;
 
 void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 			  unsigned long len, unsigned long long highmem)
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 007d5503f49b..4bdd49e0bdc3 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -12,7 +12,7 @@
 #include <os.h>
 #include <skas.h>
 
-extern int __syscall_stub_start;
+extern unsigned long __syscall_stub_start;
 
 static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 			 unsigned long kernel)
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 908579f2b0ab..f30575557791 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -193,7 +193,7 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
 	handle_syscall(regs);
 }
 
-extern int __syscall_stub_start;
+extern unsigned long __syscall_stub_start;
 
 static int userspace_tramp(void *stack)
 {
-- 
2.1.2

Re: [uml-devel] [PATCH] um: always use the same type for __syscall_stub_start

[Richard Weinberger]

Am 11.10.2014 um 13:29 schrieb Nicolas Iooss:
> syscall_stub_start is declared with different types in C files:
> 
>   arch/um/kernel/physmem.c: extern int __syscall_stub_start;
>   arch/um/kernel/skas/mmu.c: extern int __syscall_stub_start;
>   arch/um/os-Linux/skas/mem.c: extern unsigned long __syscall_stub_start;
>   arch/um/os-Linux/skas/process.c: extern int __syscall_stub_start;
> 
> Fix this inconsistency by always using unsigned long.  This does not
> change anything in the compiled code because only the address of
> __syscall_stub_start is used, but it makes the static checker I use
> stop complaining about incompatible declarations.

While we're here, can you put these declarations into a single header file?

Thanks,
//richard

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Re: [PATCH] um: always use the same type for __syscall_stub_start

[Nicolas Iooss]

2014-10-11 13:42 GMT+02:00 Richard Weinberger:
> Am 11.10.2014 um 13:29 schrieb Nicolas Iooss:
>> syscall_stub_start is declared with different types in C files:
>>
>>   arch/um/kernel/physmem.c: extern int __syscall_stub_start;
>>   arch/um/kernel/skas/mmu.c: extern int __syscall_stub_start;
>>   arch/um/os-Linux/skas/mem.c: extern unsigned long __syscall_stub_start;
>>   arch/um/os-Linux/skas/process.c: extern int __syscall_stub_start;
>>
>> Fix this inconsistency by always using unsigned long.  This does not
>> change anything in the compiled code because only the address of
>> __syscall_stub_start is used, but it makes the static checker I use
>> stop complaining about incompatible declarations.
>
> While we're here, can you put these declarations into a single header
file?

Sure.  Do you have a specific header file in mind or shall I create
arch/um/include/asm/sections.h with declarations for
__syscall_stub_start, __syscall_stub_end and __binary_start (used in
arch/um/kernel/um_arch.c)?

Thanks for your quick reply,

Nicolas

Re: [PATCH] um: always use the same type for __syscall_stub_start

[Richard Weinberger]

Am 11.10.2014 um 14:15 schrieb Nicolas Iooss:
> 2014-10-11 13:42 GMT+02:00 Richard Weinberger:
>> Am 11.10.2014 um 13:29 schrieb Nicolas Iooss:
>>> syscall_stub_start is declared with different types in C files:
>>>
>>>   arch/um/kernel/physmem.c: extern int __syscall_stub_start;
>>>   arch/um/kernel/skas/mmu.c: extern int __syscall_stub_start;
>>>   arch/um/os-Linux/skas/mem.c: extern unsigned long __syscall_stub_start;
>>>   arch/um/os-Linux/skas/process.c: extern int __syscall_stub_start;
>>>
>>> Fix this inconsistency by always using unsigned long.  This does not
>>> change anything in the compiled code because only the address of
>>> __syscall_stub_start is used, but it makes the static checker I use
>>> stop complaining about incompatible declarations.
>>
>> While we're here, can you put these declarations into a single header
> file?
> 
> Sure.  Do you have a specific header file in mind or shall I create
> arch/um/include/asm/sections.h with declarations for
> __syscall_stub_start, __syscall_stub_end and __binary_start (used in
> arch/um/kernel/um_arch.c)?

Not really. Maybe you can find a common header for all.
But I fear where is a reason why these declarations are not in a
common header. They are used in the kernel- and userspace part of
UML.
Anyway, please give it a try. :)

Thanks,
//richard

Re: [PATCH] um: always use the same type for __syscall_stub_start

[Nicolas Iooss]

Le 11/10/2014 14:24, Richard Weinberger a écrit :
> Am 11.10.2014 um 14:15 schrieb Nicolas Iooss:
>> 2014-10-11 13:42 GMT+02:00 Richard Weinberger:
>>> Am 11.10.2014 um 13:29 schrieb Nicolas Iooss:
>>>> syscall_stub_start is declared with different types in C files:
>>>>
>>>>   arch/um/kernel/physmem.c: extern int __syscall_stub_start;
>>>>   arch/um/kernel/skas/mmu.c: extern int __syscall_stub_start;
>>>>   arch/um/os-Linux/skas/mem.c: extern unsigned long __syscall_stub_start;
>>>>   arch/um/os-Linux/skas/process.c: extern int __syscall_stub_start;
>>>>
>>>> Fix this inconsistency by always using unsigned long.  This does not
>>>> change anything in the compiled code because only the address of
>>>> __syscall_stub_start is used, but it makes the static checker I use
>>>> stop complaining about incompatible declarations.
>>>
>>> While we're here, can you put these declarations into a single header
>> file?
>>
>> Sure.  Do you have a specific header file in mind or shall I create
>> arch/um/include/asm/sections.h with declarations for
>> __syscall_stub_start, __syscall_stub_end and __binary_start (used in
>> arch/um/kernel/um_arch.c)?
> 
> Not really. Maybe you can find a common header for all.
> But I fear where is a reason why these declarations are not in a
> common header. They are used in the kernel- and userspace part of
> UML.
> Anyway, please give it a try. :)

Ok.  I'll at least try to add a kernel header and send a new patch after
some tests.

By the way, most variables in include/asm-generic/sections.h are
declared "char[]" and used without operator, contrary to
__syscall_stub_start, declared "int" or "unsigned long" and only used
with "&" operator.  Is there any reason why there are in the kernel two
ways of declaring/accessing code addresses defined in linker files?  If
not, I can send a patch which makes __syscall_stub_start "char[]"
instead of "unsigned long" to make the code a little bit clearer.

Nicolas

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