linux-next: build failure after merge of the aio tree
From: bcrl@kvack.org (Benjamin LaHaise)
Date: 2016-02-04 18:48:27
Also in:
linux-next, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
On Thu, Feb 04, 2016 at 04:17:42PM +0000, Russell King - ARM Linux wrote:
__gu_val will be 32-bit, even when you're wanting a 64-bit quantity. That's where the fun and games start...
Okay, I figured out how to do it: instead of using a 64 bit unsigned long long for __gu_val, use an array of 2 unsigned longs. See the patch below which I verified boots, passes your tests and doesn't truncate 64 bit values. Comments? A simple test module to verify things is located at http://www.kvack.org/~bcrl/test_module2.c . -ben -- "Thought is the essence of where you are now."
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 09b1b0a..53244ae 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h@@ -326,7 +326,22 @@ do { \ } while (0) #ifdef CONFIG_X86_32 -#define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad() +#define __get_user_asm_u64(x, addr, err, errret) \ + asm volatile(ASM_STAC "\n" \ + "1: movl %2,%%eax\n" \ + "2: movl %3,%%edx\n" \ + "3: " ASM_CLAC "\n" \ + ".section .fixup,\"ax\"\n" \ + "4: mov %4,%0\n" \ + " xorl %%eax,%%eax\n" \ + " xorl %%edx,%%edx\n" \ + " jmp 3b\n" \ + ".previous\n" \ + _ASM_EXTABLE(1b, 4b) \ + _ASM_EXTABLE(2b, 4b) \ + : "=r" (err), "=A"(x) \ + : "m" (__m(addr)), "m" __m(((u32 *)addr) + 1), "i" (errret), "0" (err)) + #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad() #else #define __get_user_asm_u64(x, ptr, retval, errret) \
@@ -407,9 +422,16 @@ do { \ #define __get_user_nocheck(x, ptr, size) \ ({ \ int __gu_err; \ - unsigned long __gu_val; \ - __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ - (x) = (__force __typeof__(*(ptr)))__gu_val; \ + if (size == 8) { \ + unsigned long __gu_val[2]; \ + __gu_err = 0; \ + __get_user_asm_u64(__gu_val, ptr, __gu_err, -EFAULT); \ + (x) = *(__force __typeof__((ptr)))__gu_val; \ + } else { \ + unsigned long __gu_val; \ + __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ + (x) = (__force __typeof__(*(ptr)))__gu_val; \ + } \ __builtin_expect(__gu_err, 0); \ })