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Diffstat (limited to 'arch/nds32/include/uapi/asm/sigcontext.h')
-rw-r--r--arch/nds32/include/uapi/asm/sigcontext.h24
1 files changed, 17 insertions, 7 deletions
diff --git a/arch/nds32/include/uapi/asm/sigcontext.h b/arch/nds32/include/uapi/asm/sigcontext.h
index 628ff6b75825..dc89af7ddcc3 100644
--- a/arch/nds32/include/uapi/asm/sigcontext.h
+++ b/arch/nds32/include/uapi/asm/sigcontext.h
@@ -13,14 +13,24 @@ struct fpu_struct {
unsigned long long fd_regs[32];
unsigned long fpcsr;
/*
- * UDF_trap is used to recognize whether underflow trap is enabled
- * or not. When UDF_trap == 1, this process will be traped and then
- * get a SIGFPE signal when encountering an underflow exception.
- * UDF_trap is only modified through setfputrap syscall. Therefore,
- * UDF_trap needn't be saved or loaded to context in each context
- * switch.
+ * When CONFIG_SUPPORT_DENORMAL_ARITHMETIC is defined, kernel prevents
+ * hardware from treating the denormalized output as an underflow case
+ * and rounding it to a normal number. Hence kernel enables the UDF and
+ * IEX trap in the fpcsr register to step in the calculation.
+ * However, the UDF and IEX trap enable bit in $fpcsr also lose
+ * their use.
+ *
+ * UDF_IEX_trap replaces the feature of UDF and IEX trap enable bit in
+ * $fpcsr to control the trap of underflow and inexact. The bit filed
+ * of UDF_IEX_trap is the same as $fpcsr, 10th bit is used to enable UDF
+ * exception trapping and 11th bit is used to enable IEX exception
+ * trapping.
+ *
+ * UDF_IEX_trap is only modified through fp_udfiex_crtl syscall.
+ * Therefore, UDF_IEX_trap needn't be saved and restored in each
+ * context switch.
*/
- unsigned long UDF_trap;
+ unsigned long UDF_IEX_trap;
};
struct zol_struct {