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. -- Ville Syrjälä Intel OTC -- 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/
