Merge tag 'v5.2-rc4' into regulator-5.3

Linux 5.2-rc4

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 {