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sparc/compat: provide an accurate in_compat_syscall implementation 

On sparc64 compat-enabled kernels, any task can make 32-bit and 64-bit
syscalls.  is_compat_task returns true in 32-bit tasks, which does not
necessarily imply that the current syscall is 32-bit.

Provide an in_compat_syscall implementation that checks whether the
current syscall is compat.

As far as I know, sparc is the only architecture on which is_compat_task
checks the compat status of the task and on which the compat status of a
syscall can differ from the compat status of the task.  On x86,
is_compat_task checks the syscall type, not the task type.

[akpm@linux-foundation.org: add comment, per Sam]
[akpm@linux-foundation.org: update comment, per Andy]
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andy Lutomirski 2016-03-22 14:24:46 -07:00 committed by Linus Torvalds
parent 5180e3e24f
commit 069923d87e
1 changed files with 7 additions and 0 deletions
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7
arch/sparc/include/asm/compat.h
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@ -307,4 +307,11 @@ static inline int is_compat_task(void)
return test_thread_flag(TIF_32BIT);
}
static inline bool in_compat_syscall(void)
{
/* Vector 0x110 is LINUX_32BIT_SYSCALL_TRAP */
return pt_regs_trap_type(current_pt_regs()) == 0x110;
}
#define in_compat_syscall in_compat_syscall
#endif /* _ASM_SPARC64_COMPAT_H */