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>hifive-unleashed-5.1
Ville Syrjälä
H. Peter Anvin
parent
07f4207a30
commit
96477b4cd7
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@ -151,8 +151,15 @@ extern int __get_user_bad(void);
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* On error, the variable @x is set to zero.
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*/
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#ifdef CONFIG_X86_32
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#define __get_user_8(__ret_gu, __val_gu, ptr) \
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__get_user_x(X, __ret_gu, __val_gu, ptr)
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#define __get_user_8(ret, x, ptr) \
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do { \
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register unsigned long long __xx asm("%edx"); \
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asm volatile("call __get_user_8" \
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: "=a" (ret), "=r" (__xx) \
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: "0" (ptr)); \
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(x) = __xx; \
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} while (0)
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#else
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#define __get_user_8(__ret_gu, __val_gu, ptr) \
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__get_user_x(8, __ret_gu, __val_gu, ptr)
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@ -162,6 +169,7 @@ extern int __get_user_bad(void);
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({ \
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int __ret_gu; \
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unsigned long __val_gu; \
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unsigned long long __val_gu8; \
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__chk_user_ptr(ptr); \
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might_fault(); \
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switch (sizeof(*(ptr))) { \
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@ -175,13 +183,16 @@ extern int __get_user_bad(void);
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__get_user_x(4, __ret_gu, __val_gu, ptr); \
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break; \
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case 8: \
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__get_user_8(__ret_gu, __val_gu, ptr); \
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__get_user_8(__ret_gu, __val_gu8, ptr); \
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break; \
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default: \
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__get_user_x(X, __ret_gu, __val_gu, ptr); \
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break; \
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} \
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(x) = (__typeof__(*(ptr)))__val_gu; \
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if (sizeof(*(ptr)) == 8) \
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(x) = (__typeof__(*(ptr)))__val_gu8; \
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else \
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(x) = (__typeof__(*(ptr)))__val_gu; \
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__ret_gu; \
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})
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@ -26,6 +26,7 @@ EXPORT_SYMBOL(csum_partial_copy_generic);
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EXPORT_SYMBOL(__get_user_1);
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EXPORT_SYMBOL(__get_user_2);
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EXPORT_SYMBOL(__get_user_4);
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EXPORT_SYMBOL(__get_user_8);
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EXPORT_SYMBOL(__put_user_1);
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EXPORT_SYMBOL(__put_user_2);
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@ -15,11 +15,10 @@
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* __get_user_X
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*
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* Inputs: %[r|e]ax contains the address.
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* The register is modified, but all changes are undone
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* before returning because the C code doesn't know about it.
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*
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* Outputs: %[r|e]ax is error code (0 or -EFAULT)
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* %[r|e]dx contains zero-extended value
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* %ecx contains the high half for 32-bit __get_user_8
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*
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*
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* These functions should not modify any other registers,
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@ -79,22 +78,35 @@ ENTRY(__get_user_4)
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CFI_ENDPROC
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ENDPROC(__get_user_4)
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#ifdef CONFIG_X86_64
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ENTRY(__get_user_8)
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CFI_STARTPROC
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#ifdef CONFIG_X86_64
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add $7,%_ASM_AX
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jc bad_get_user
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GET_THREAD_INFO(%_ASM_DX)
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cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
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jae bad_get_user
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jae bad_get_user
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ASM_STAC
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4: movq -7(%_ASM_AX),%_ASM_DX
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xor %eax,%eax
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ASM_CLAC
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ret
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#else
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add $7,%_ASM_AX
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jc bad_get_user_8
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GET_THREAD_INFO(%_ASM_DX)
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cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
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jae bad_get_user_8
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ASM_STAC
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4: mov -7(%_ASM_AX),%edx
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5: mov -3(%_ASM_AX),%ecx
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xor %eax,%eax
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ASM_CLAC
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ret
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#endif
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CFI_ENDPROC
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ENDPROC(__get_user_8)
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#endif
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bad_get_user:
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CFI_STARTPROC
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@ -105,9 +117,24 @@ bad_get_user:
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CFI_ENDPROC
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END(bad_get_user)
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#ifdef CONFIG_X86_32
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bad_get_user_8:
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CFI_STARTPROC
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xor %edx,%edx
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xor %ecx,%ecx
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mov $(-EFAULT),%_ASM_AX
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ASM_CLAC
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ret
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CFI_ENDPROC
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END(bad_get_user_8)
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#endif
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_ASM_EXTABLE(1b,bad_get_user)
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_ASM_EXTABLE(2b,bad_get_user)
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_ASM_EXTABLE(3b,bad_get_user)
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#ifdef CONFIG_X86_64
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_ASM_EXTABLE(4b,bad_get_user)
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#else
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_ASM_EXTABLE(4b,bad_get_user_8)
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_ASM_EXTABLE(5b,bad_get_user_8)
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#endif
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