On 04/18/2019 06:55 AM, Michael Ellerman wrote:
Christophe Leroy <christophe.le...@c-s.fr> writes:
diff --git a/arch/powerpc/include/asm/book3s/32/kup.h
b/arch/powerpc/include/asm/book3s/32/kup.h
index 5f97c742ca71..b3560b2de435 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -37,6 +37,113 @@
...
+
+static inline void allow_user_access(void __user *to, const void __user *from,
u32 size)
+{
+ u32 addr = (__force u32)to;
+ u32 end = min(addr + size, TASK_SIZE);
+
+ if (!addr || addr >= TASK_SIZE || !size)
+ return;
+
+ current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) &
0xf);
+ kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end); /* Clear Ks */
+}
When rebasing on my v6 I changed the above to:
static inline void allow_user_access(void __user *to, const void __user *from,
u32 size)
{
u32 addr, end;
if (__builtin_constant_p(to) && to == NULL)
return;
Look like the above doesn't work: gcc bug ?
#define NULL (void*)0
static inline int f1(void *to)
{
if (__builtin_constant_p(to) && to == NULL)
return 3;
return 5;
}
int g1(void)
{
return f1(NULL);
}
static inline int f2(int x)
{
if (__builtin_constant_p(x) && x == 0)
return 7;
return 9;
}
int g2(void)
{
return f2(0);
}
toto.o: file format elf32-powerpc
Disassembly of section .text:
00000000 <g1>:
0: 38 60 00 05 li r3,5
4: 4e 80 00 20 blr
00000008 <g2>:
8: 38 60 00 07 li r3,7
c: 4e 80 00 20 blr
It works for the int const, but not for the pointer const:
g1() should return 3, not 5. GCC bug ?
Christophe
