xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86/entry: Use SYSCALL_DEFINE() macros for sys_modify_ldt()

Browse Source 
We do not have tracepoints for sys_modify_ldt() because we define
it directly instead of using the normal SYSCALL_DEFINEx() macros.

However, there is a reason sys_modify_ldt() does not use the macros:
it has an 'int' return type instead of 'unsigned long'.  This is
a bug, but it's a bug cemented in the ABI.

What does this mean?  If we return -EINVAL from a function that
returns 'int', we have 0x00000000ffffffea in %rax.  But, if we
return -EINVAL from a function returning 'unsigned long', we end
up with 0xffffffffffffffea in %rax, which is wrong.

To work around this and maintain the 'int' behavior while using
the SYSCALL_DEFINEx() macros, so we add a cast to 'unsigned int'
in both implementations of sys_modify_ldt().

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Brian Gerst <brgerst@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171018172107.1A79C532@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dave Hansen
2017-10-18 10:21:07 -07:00
committed by Ingo Molnar
parent fc72ae40e3
commit da20ab3518
3 changed files with 19 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/include/asm/syscalls.h
View File

@@ -21,7 +21,7 @@ asmlinkage long sys_ioperm(unsigned long, unsigned long, int);
asmlinkage long sys_iopl(unsigned int);
/* kernel/ldt.c */
asmlinkage int sys_modify_ldt(int, void __user *, unsigned long);
asmlinkage long sys_modify_ldt(int, void __user *, unsigned long);
/* kernel/signal.c */
asmlinkage long sys_rt_sigreturn(void);