On Wed, Jan 18, 2006 at 01:37:59PM +0000, Martin Michlmayr wrote: > * Ralf Baechle <ralf@xxxxxxxxxxxxxx> [2006-01-18 13:05]: > > > With current linux-mips git I still get the problem. As a reminder, > > > the error is: > > > > > > CC fs/compat_ioctl.o > > > fs/compat_ioctl.c: In function 'fd_ioctl_trans': > > > fs/compat_ioctl.c:1831: error: read-only variable '__gu_val' used as 'asm' output > > I have not been able to find some construct that keeps gcc happy and at the > > same time doesn't result in significantly worse code. That matters because > > get_user / put_user are used very often throughout the kernel. > > Who could help with that? Maciej? David Daney? > > (See the original discussion and the proposed patch at > http://www.spinics.net/lists/mips/msg20671.html) I'd appreciate if somebody with gcc 4.0.1 could test this kernel patch below. Ralf include/asm-mips/uaccess.h | 71 ++++++++++++++++++++++----------------------- 1 files changed, 36 insertions(+), 35 deletions(-) Index: linux-mips/include/asm-mips/uaccess.h =================================================================== --- linux-mips.orig/include/asm-mips/uaccess.h +++ linux-mips/include/asm-mips/uaccess.h @@ -202,49 +202,49 @@ struct __large_struct { unsigned long bu * Yuck. We need two variants, one for 64bit operation and one * for 32 bit mode and old iron. */ -#ifdef __mips64 -#define __GET_USER_DW(ptr) __get_user_asm("ld", ptr) -#else -#define __GET_USER_DW(ptr) __get_user_asm_ll32(ptr) +#ifdef CONFIG_32BIT +#define __GET_USER_DW(val, ptr) __get_user_asm_ll32(val, ptr) +#endif +#ifdef CONFIG_64BIT +#define __GET_USER_DW(val, ptr) __get_user_asm(val, "ld", ptr) #endif -#define __get_user_nocheck(x,ptr,size) \ -({ \ - __typeof(*(ptr)) __gu_val = (__typeof(*(ptr))) 0; \ - long __gu_err = 0; \ - \ +extern void __get_user_unknown(void); + +#define __get_user_common(val, size, ptr) \ +do { \ switch (size) { \ - case 1: __get_user_asm("lb", ptr); break; \ - case 2: __get_user_asm("lh", ptr); break; \ - case 4: __get_user_asm("lw", ptr); break; \ - case 8: __GET_USER_DW(ptr); break; \ + case 1: __get_user_asm(val, "lb", ptr); break; \ + case 2: __get_user_asm(val, "lh", ptr); break; \ + case 4: __get_user_asm(val, "lw", ptr); break; \ + case 8: __GET_USER_DW(val, ptr); break; \ default: __get_user_unknown(); break; \ } \ - (x) = (__typeof__(*(ptr))) __gu_val; \ +} while (0) + +#define __get_user_nocheck(x,ptr,size) \ +({ \ + long __gu_err; \ + \ + __get_user_common((x), size, ptr); \ __gu_err; \ }) #define __get_user_check(x,ptr,size) \ ({ \ - const __typeof__(*(ptr)) __user * __gu_addr = (ptr); \ - __typeof__(*(ptr)) __gu_val = 0; \ long __gu_err = -EFAULT; \ + void * __gu_ptr = (ptr); \ + \ + if (likely(access_ok(VERIFY_READ, __gu_ptr, size))) \ + __get_user_common((x), size, __gu_ptr); \ \ - if (likely(access_ok(VERIFY_READ, __gu_addr, size))) { \ - switch (size) { \ - case 1: __get_user_asm("lb", __gu_addr); break; \ - case 2: __get_user_asm("lh", __gu_addr); break; \ - case 4: __get_user_asm("lw", __gu_addr); break; \ - case 8: __GET_USER_DW(__gu_addr); break; \ - default: __get_user_unknown(); break; \ - } \ - } \ - (x) = (__typeof__(*(ptr))) __gu_val; \ __gu_err; \ }) -#define __get_user_asm(insn, addr) \ +#define __get_user_asm(val, insn, addr) \ { \ + long __gu_tmp; \ + \ __asm__ __volatile__( \ "1: " insn " %1, %3 \n" \ "2: \n" \ @@ -255,14 +255,16 @@ struct __large_struct { unsigned long bu " .section __ex_table,\"a\" \n" \ " "__UA_ADDR "\t1b, 3b \n" \ " .previous \n" \ - : "=r" (__gu_err), "=r" (__gu_val) \ + : "=r" (__gu_err), "=r" (__gu_tmp) \ : "0" (0), "o" (__m(addr)), "i" (-EFAULT)); \ + \ + (val) = (__typeof__(val)) __gu_tmp; \ } /* * Get a long long 64 using 32 bit registers. */ -#define __get_user_asm_ll32(addr) \ +#define __get_user_asm_ll32(val, addr) \ { \ __asm__ __volatile__( \ "1: lw %1, (%3) \n" \ @@ -278,21 +280,20 @@ struct __large_struct { unsigned long bu " " __UA_ADDR " 1b, 4b \n" \ " " __UA_ADDR " 2b, 4b \n" \ " .previous \n" \ - : "=r" (__gu_err), "=&r" (__gu_val) \ + : "=r" (__gu_err), "=&r" (val) \ : "0" (0), "r" (addr), "i" (-EFAULT)); \ } -extern void __get_user_unknown(void); - /* * Yuck. We need two variants, one for 64bit operation and one * for 32 bit mode and old iron. */ -#ifdef __mips64 -#define __PUT_USER_DW(ptr) __put_user_asm("sd", ptr) -#else +#ifdef CONFIG_32BIT #define __PUT_USER_DW(ptr) __put_user_asm_ll32(ptr) #endif +#ifdef CONFIG_64BIT +#define __PUT_USER_DW(ptr) __put_user_asm("sd", ptr) +#endif #define __put_user_nocheck(x,ptr,size) \ ({ \
