diff options
| author | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2012-12-12 13:34:03 +0200 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2013-02-07 15:07:28 -0800 |
| commit | 96477b4cd705c5416346aef262b0a1116cfcdd80 (patch) | |
| tree | fcc031d7eb37e0eeef361e65102c260c8b62490b /arch/x86/lib | |
| parent | 07f4207a305c834f528d08428df4531744e25678 (diff) | |
x86-32: Add support for 64bit get_user()
Implement __get_user_8() for x86-32. It will return the
64-bit result in edx:eax register pair, and ecx is used
to pass in the address and return the error value.
For consistency, change the register assignment for all
other __get_user_x() variants, so that address is passed in
ecx/rcx, the error value is returned in ecx/rcx, and eax/rax
contains the actual value.
[ hpa: I modified the patch so that it does NOT change the calling
conventions for the existing callsites, this also means that the code
is completely unchanged for 64 bits.
Instead, continue to use eax for address input/error output and use
the ecx:edx register pair for the output. ]
This is a partial refresh of a patch [1] by Jamie Lokier from
2004. Only the minimal changes to implement 64bit get_user()
were picked from the original patch.
[1] http://article.gmane.org/gmane.linux.kernel/198823
Originally-by: Jamie Lokier <jamie@shareable.org>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link:
http://lkml.kernel.org/r/1355312043-11467-1-git-send-email-ville.syrjala@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/lib')
| -rw-r--r-- | arch/x86/lib/getuser.S | 37 |
1 files changed, 32 insertions, 5 deletions
diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S index 156b9c80467..d3bf9f99ca7 100644 --- a/arch/x86/lib/getuser.S +++ b/arch/x86/lib/getuser.S @@ -15,11 +15,10 @@ * __get_user_X * * Inputs: %[r|e]ax contains the address. - * The register is modified, but all changes are undone - * before returning because the C code doesn't know about it. * * Outputs: %[r|e]ax is error code (0 or -EFAULT) * %[r|e]dx contains zero-extended value + * %ecx contains the high half for 32-bit __get_user_8 * * * These functions should not modify any other registers, @@ -79,22 +78,35 @@ ENTRY(__get_user_4) CFI_ENDPROC ENDPROC(__get_user_4) -#ifdef CONFIG_X86_64 ENTRY(__get_user_8) CFI_STARTPROC +#ifdef CONFIG_X86_64 add $7,%_ASM_AX jc bad_get_user GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX - jae bad_get_user + jae bad_get_user ASM_STAC 4: movq -7(%_ASM_AX),%_ASM_DX xor %eax,%eax ASM_CLAC ret +#else + add $7,%_ASM_AX + jc bad_get_user_8 + GET_THREAD_INFO(%_ASM_DX) + cmp TI_addr_limit(%_ASM_DX),%_ASM_AX + jae bad_get_user_8 + ASM_STAC +4: mov -7(%_ASM_AX),%edx +5: mov -3(%_ASM_AX),%ecx + xor %eax,%eax + ASM_CLAC + ret +#endif CFI_ENDPROC ENDPROC(__get_user_8) -#endif + bad_get_user: CFI_STARTPROC @@ -105,9 +117,24 @@ bad_get_user: CFI_ENDPROC END(bad_get_user) +#ifdef CONFIG_X86_32 +bad_get_user_8: + CFI_STARTPROC + xor %edx,%edx + xor %ecx,%ecx + mov $(-EFAULT),%_ASM_AX + ASM_CLAC + ret + CFI_ENDPROC +END(bad_get_user_8) +#endif + _ASM_EXTABLE(1b,bad_get_user) _ASM_EXTABLE(2b,bad_get_user) _ASM_EXTABLE(3b,bad_get_user) #ifdef CONFIG_X86_64 _ASM_EXTABLE(4b,bad_get_user) +#else + _ASM_EXTABLE(4b,bad_get_user_8) + _ASM_EXTABLE(5b,bad_get_user_8) #endif |