A build failure was raised by kbuild with the following error.
drivers/android/binder.c: Assembler messages:
drivers/android/binder.c:3861: Error: unrecognized keyword/register name
`l.lwz ?ap,4(r24)'
drivers/android/binder.c:3866: Error: unrecognized keyword/register name
`l.addi ?ap,r0,0'
The issue is with 64-bit get_user() calls on openrisc. I traced this to
a problem where in the internally in the get_user macros there is a cast
to long __gu_val this causes GCC to think the get_user call is 32-bit.
This binder code is really long and GCC allocates register r30, which
triggers the issue. The 64-bit get_user asm tries to get the 64-bit pair
register, which for r30 overflows the general register names and returns
the dummy register ?ap.
The fix is to just remove the assignment to the 32-bit temporary
variable __gu_val.
Link: https://lore.kernel.org/lkml/202008200453.ohnhqkjq%25...@intel.com/
Signed-off-by: Stafford Horne <sho...@gmail.com>
---
arch/openrisc/include/asm/uaccess.h | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/openrisc/include/asm/uaccess.h
b/arch/openrisc/include/asm/uaccess.h
index f0390211236b..4a8976dda1a5 100644
--- a/arch/openrisc/include/asm/uaccess.h
+++ b/arch/openrisc/include/asm/uaccess.h
@@ -165,19 +165,19 @@ struct __large_struct {
#define __get_user_nocheck(x, ptr, size) \
({ \
- long __gu_err, __gu_val; \
- __get_user_size(__gu_val, (ptr), (size), __gu_err); \
- (x) = (__force __typeof__(*(ptr)))__gu_val; \
+ long __gu_err; \
+ __get_user_size((x), (ptr), (size), __gu_err); \
__gu_err; \
})
#define __get_user_check(x, ptr, size) \
({ \
- long __gu_err = -EFAULT, __gu_val = 0; \
+ long __gu_err = -EFAULT; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
- if (access_ok(__gu_addr, size)) \
- __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
- (x) = (__force __typeof__(*(ptr)))__gu_val; \
+ if (access_ok(__gu_addr, size)) \
+ __get_user_size((x), __gu_addr, (size), __gu_err); \
+ else \
+ (x) = 0; \
__gu_err; \
})
@@ -191,7 +191,7 @@ do {
\
case 2: __get_user_asm(x, ptr, retval, "l.lhz"); break; \
case 4: __get_user_asm(x, ptr, retval, "l.lwz"); break; \
case 8: __get_user_asm2(x, ptr, retval); break; \
- default: (x) = __get_user_bad(); \
+ default: (x) = (__typeof__(x)) __get_user_bad(); \
} \
} while (0)
--
2.26.2
