diff options
Diffstat (limited to 'arch/parisc/include/asm/special_insns.h')
| -rw-r--r-- | arch/parisc/include/asm/special_insns.h | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/arch/parisc/include/asm/special_insns.h b/arch/parisc/include/asm/special_insns.h index 51f40eaf7780..1013eeba31e5 100644 --- a/arch/parisc/include/asm/special_insns.h +++ b/arch/parisc/include/asm/special_insns.h @@ -32,6 +32,34 @@ pa; \ }) +/** + * prober_user() - Probe user read access + * @sr: Space regster. + * @va: Virtual address. + * + * Return: Non-zero if address is accessible. + * + * Due to the way _PAGE_READ is handled in TLB entries, we need + * a special check to determine whether a user address is accessible. + * The ldb instruction does the initial access check. If it is + * successful, the probe instruction checks user access rights. + */ +#define prober_user(sr, va) ({ \ + unsigned long read_allowed; \ + __asm__ __volatile__( \ + "copy %%r0,%0\n" \ + "8:\tldb 0(%%sr%1,%2),%%r0\n" \ + "\tproberi (%%sr%1,%2),%3,%0\n" \ + "9:\n" \ + ASM_EXCEPTIONTABLE_ENTRY(8b, 9b, \ + "or %%r0,%%r0,%%r0") \ + : "=&r" (read_allowed) \ + : "i" (sr), "r" (va), "i" (PRIV_USER) \ + : "memory" \ + ); \ + read_allowed; \ +}) + #define CR_EIEM 15 /* External Interrupt Enable Mask */ #define CR_CR16 16 /* CR16 Interval Timer */ #define CR_EIRR 23 /* External Interrupt Request Register */ |