It's a good change -- and one which opens up even more unification -- but right now we're worried about 3.8.
"Ville Syrjälä" <ville.syrj...@linux.intel.com> wrote: >On Wed, Dec 12, 2012 at 08:15:12AM -0800, H. Peter Anvin wrote: >> Can we worry about this after the merge window? > >Sure. The only use I have for this is in my drm/kms atomic >modeset/pageflip patch set, and that's not 3.8 material. > >> >> ville.syrj...@linux.intel.com wrote: >> >> >From: Ville Syrjälä <ville.syrj...@linux.intel.com> >> > >> >Implement __get_user_8() for x86-32. It will return the >> >64bit 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. >> > >> >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 >> > >> >Cc: Jamie Lokier <ja...@shareable.org> >> >Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com> >> >--- >> > arch/x86/include/asm/uaccess.h | 17 ++++++-- >> > arch/x86/kernel/i386_ksyms_32.c | 1 + >> >arch/x86/lib/getuser.S | 82 >> >++++++++++++++++++++++++++------------ >> > 3 files changed, 69 insertions(+), 31 deletions(-) >> > >> >diff --git a/arch/x86/include/asm/uaccess.h >> >b/arch/x86/include/asm/uaccess.h >> >index 7ccf8d1..3f4387e 100644 >> >--- a/arch/x86/include/asm/uaccess.h >> >+++ b/arch/x86/include/asm/uaccess.h >> >@@ -127,7 +127,7 @@ extern int __get_user_bad(void); >> > >> > #define __get_user_x(size, ret, x, ptr) \ >> > asm volatile("call __get_user_" #size \ >> >- : "=a" (ret), "=d" (x) \ >> >+ : "=c" (ret), "=a" (x) \ >> > : "0" (ptr)) \ >> > >> > /* Careful: we have to cast the result to the type of the pointer >> >@@ -151,8 +151,11 @@ extern int __get_user_bad(void); >> > * On error, the variable @x is set to zero. >> > */ >> > #ifdef CONFIG_X86_32 >> >-#define __get_user_8(__ret_gu, __val_gu, ptr) >> >\ >> >- __get_user_x(X, __ret_gu, __val_gu, ptr) >> >+#define __get_user_8(ret, x, ptr) \ >> >+ asm volatile("call __get_user_8" \ >> >+ : "=c" (ret), "=A" (x) \ >> >+ : "0" (ptr)) \ >> >+ >> > #else >> > #define __get_user_8(__ret_gu, __val_gu, ptr) >> > \ >> > __get_user_x(8, __ret_gu, __val_gu, ptr) >> >@@ -162,6 +165,7 @@ extern int __get_user_bad(void); >> > ({ \ >> > int __ret_gu; \ >> > unsigned long __val_gu; \ >> >+ unsigned long long __val_gu8; \ >> > __chk_user_ptr(ptr); \ >> > might_fault(); \ >> > switch (sizeof(*(ptr))) { \ >> >@@ -175,13 +179,16 @@ extern int __get_user_bad(void); >> > __get_user_x(4, __ret_gu, __val_gu, ptr); \ >> > break; \ >> > case 8: \ >> >- __get_user_8(__ret_gu, __val_gu, ptr); \ >> >+ __get_user_8(__ret_gu, __val_gu8, ptr); \ >> > break; \ >> > default: \ >> > __get_user_x(X, __ret_gu, __val_gu, ptr); \ >> > break; \ >> > } \ >> >- (x) = (__typeof__(*(ptr)))__val_gu; \ >> >+ if (sizeof(*(ptr)) == 8) \ >> >+ (x) = (__typeof__(*(ptr)))__val_gu8; \ >> >+ else \ >> >+ (x) = (__typeof__(*(ptr)))__val_gu; \ >> > __ret_gu; \ >> > }) >> > >> >diff --git a/arch/x86/kernel/i386_ksyms_32.c >> >b/arch/x86/kernel/i386_ksyms_32.c >> >index 9c3bd4a..0fa6912 100644 >> >--- a/arch/x86/kernel/i386_ksyms_32.c >> >+++ b/arch/x86/kernel/i386_ksyms_32.c >> >@@ -26,6 +26,7 @@ EXPORT_SYMBOL(csum_partial_copy_generic); >> > EXPORT_SYMBOL(__get_user_1); >> > EXPORT_SYMBOL(__get_user_2); >> > EXPORT_SYMBOL(__get_user_4); >> >+EXPORT_SYMBOL(__get_user_8); >> > >> > EXPORT_SYMBOL(__put_user_1); >> > EXPORT_SYMBOL(__put_user_2); >> >diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S >> >index 156b9c8..38afef0 100644 >> >--- a/arch/x86/lib/getuser.S >> >+++ b/arch/x86/lib/getuser.S >> >@@ -14,12 +14,11 @@ >> > /* >> > * __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. >> >+ * Inputs: %[r|e]cx contains the address. >> > * >> >- * Outputs: %[r|e]ax is error code (0 or -EFAULT) >> >- * %[r|e]dx contains zero-extended value >> >+ * Outputs: %[r|e]cx is error code (0 or -EFAULT) >> >+ * %[r|e]ax contains zero-extended value >> >+ * %edx contains the high bits of the value for __get_user_8 on >> >x86-32 >> > * >> > * >> > * These functions should not modify any other registers, >> >@@ -38,12 +37,12 @@ >> > .text >> > ENTRY(__get_user_1) >> > CFI_STARTPROC >> >- GET_THREAD_INFO(%_ASM_DX) >> >- cmp TI_addr_limit(%_ASM_DX),%_ASM_AX >> >+ GET_THREAD_INFO(%_ASM_AX) >> >+ cmp TI_addr_limit(%_ASM_AX),%_ASM_CX >> > jae bad_get_user >> > ASM_STAC >> >-1: movzb (%_ASM_AX),%edx >> >- xor %eax,%eax >> >+1: movzb (%_ASM_CX),%eax >> >+ xor %ecx,%ecx >> > ASM_CLAC >> > ret >> > CFI_ENDPROC >> >@@ -51,14 +50,14 @@ ENDPROC(__get_user_1) >> > >> > ENTRY(__get_user_2) >> > CFI_STARTPROC >> >- add $1,%_ASM_AX >> >+ add $1,%_ASM_CX >> > jc bad_get_user >> >- GET_THREAD_INFO(%_ASM_DX) >> >- cmp TI_addr_limit(%_ASM_DX),%_ASM_AX >> >+ GET_THREAD_INFO(%_ASM_AX) >> >+ cmp TI_addr_limit(%_ASM_AX),%_ASM_CX >> > jae bad_get_user >> > ASM_STAC >> >-2: movzwl -1(%_ASM_AX),%edx >> >- xor %eax,%eax >> >+2: movzwl -1(%_ASM_CX),%eax >> >+ xor %ecx,%ecx >> > ASM_CLAC >> > ret >> > CFI_ENDPROC >> >@@ -66,14 +65,14 @@ ENDPROC(__get_user_2) >> > >> > ENTRY(__get_user_4) >> > CFI_STARTPROC >> >- add $3,%_ASM_AX >> >+ add $3,%_ASM_CX >> > jc bad_get_user >> >- GET_THREAD_INFO(%_ASM_DX) >> >- cmp TI_addr_limit(%_ASM_DX),%_ASM_AX >> >+ GET_THREAD_INFO(%_ASM_AX) >> >+ cmp TI_addr_limit(%_ASM_AX),%_ASM_CX >> > jae bad_get_user >> > ASM_STAC >> >-3: mov -3(%_ASM_AX),%edx >> >- xor %eax,%eax >> >+3: mov -3(%_ASM_CX),%eax >> >+ xor %ecx,%ecx >> > ASM_CLAC >> > ret >> > CFI_ENDPROC >> >@@ -82,14 +81,30 @@ ENDPROC(__get_user_4) >> > #ifdef CONFIG_X86_64 >> > ENTRY(__get_user_8) >> > CFI_STARTPROC >> >- add $7,%_ASM_AX >> >+ add $7,%_ASM_CX >> > jc bad_get_user >> >- GET_THREAD_INFO(%_ASM_DX) >> >- cmp TI_addr_limit(%_ASM_DX),%_ASM_AX >> >+ GET_THREAD_INFO(%_ASM_AX) >> >+ cmp TI_addr_limit(%_ASM_AX),%_ASM_CX >> > jae bad_get_user >> > ASM_STAC >> >-4: movq -7(%_ASM_AX),%_ASM_DX >> >- xor %eax,%eax >> >+4: movq -7(%_ASM_CX),%_ASM_AX >> >+ xor %ecx,%ecx >> >+ ASM_CLAC >> >+ ret >> >+ CFI_ENDPROC >> >+ENDPROC(__get_user_8) >> >+#else >> >+ENTRY(__get_user_8) >> >+ CFI_STARTPROC >> >+ add $7,%_ASM_CX >> >+ jc bad_get_user_8 >> >+ GET_THREAD_INFO(%_ASM_AX) >> >+ cmp TI_addr_limit(%_ASM_AX),%_ASM_CX >> >+ jae bad_get_user_8 >> >+ ASM_STAC >> >+4: mov -7(%_ASM_CX),%eax >> >+5: mov -3(%_ASM_CX),%edx >> >+ xor %ecx,%ecx >> > ASM_CLAC >> > ret >> > CFI_ENDPROC >> >@@ -98,16 +113,31 @@ ENDPROC(__get_user_8) >> > >> > bad_get_user: >> > CFI_STARTPROC >> >- xor %edx,%edx >> >- mov $(-EFAULT),%_ASM_AX >> >+ xor %eax,%eax >> >+ mov $(-EFAULT),%_ASM_CX >> > ASM_CLAC >> > ret >> > CFI_ENDPROC >> > END(bad_get_user) >> > >> >+#ifdef CONFIG_X86_32 >> >+bad_get_user_8: >> >+ CFI_STARTPROC >> >+ xor %eax,%eax >> >+ xor %edx,%edx >> >+ mov $(-EFAULT),%_ASM_CX >> >+ 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 >> >> -- >> Sent from my mobile phone. Please excuse brevity and lack of >formatting. -- Sent from my mobile phone. Please excuse brevity and lack of formatting. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
