sw64: remove trap_a* and hae from pt_regs

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56OLG

--------------------------------

At present, glibc dumps `trap_a*` when a segmentation fault is caught,
but no user knows what they mean. That is, nobody care about them, so
remove them to reduce overhead of SAVE_COMMON_REGS.

Besides, `hae` is legacy code which should be deprecated too.
Signed-off-by: NHe Sheng <hesheng@wxiat.com>
Signed-off-by: NGu Zitao <guzitao@wxiat.com>

arch/sw_64/include/asm/ptrace.h

@@ -40,12 +40,7 @@ struct pt_regs {
 	unsigned long r26;
 	unsigned long r27;
 	unsigned long r28;
-	unsigned long hae;
-/* JRP - These are the values provided to a0-a2 by HMcode */
-	unsigned long trap_a0;
-	unsigned long trap_a1;
-	unsigned long trap_a2;
-/* These are saved by HMcode: */
+	/* These are saved by HMcode: */
 	unsigned long ps;
 	unsigned long pc;
 	unsigned long gp;

arch/sw_64/include/uapi/asm/sigcontext.h

@@ -2,15 +2,13 @@
 #ifndef _UAPI_ASM_SW64_SIGCONTEXT_H
 #define _UAPI_ASM_SW64_SIGCONTEXT_H
 
+/*
+ * Signal context structure
+ *
+ * The context is saved before a signal handler is invoked, and it is
+ * restored by sys_sigreturn / sys_rt_sigreturn.
+ */
 struct sigcontext {
-	/*
-	 * What should we have here? I'd probably better use the same
-	 * stack layout as DEC Unix, just in case we ever want to try
-	 * running their binaries..
-	 *
-	 * This is the basic layout, but I don't know if we'll ever
-	 * actually fill in all the values..
-	 */
 	long		sc_onstack;
 	long		sc_mask;
 	long		sc_pc;
@@ -19,6 +17,7 @@ struct sigcontext {
 	long		sc_ownedfp;
 	long		sc_fpregs[128];	/* SIMD-FP */
 	unsigned long	sc_fpcr;
+	/* TODO: Following are unused, to be removed and synced with libc */
 	unsigned long	sc_fp_control;
 	unsigned long	sc_reserved1, sc_reserved2;
 	unsigned long	sc_ssize;

arch/sw_64/kernel/asm-offsets.c

@@ -88,9 +88,6 @@ void foo(void)
 	DEFINE(PT_REGS_R26, offsetof(struct pt_regs, r26));
 	DEFINE(PT_REGS_R27, offsetof(struct pt_regs, r27));
 	DEFINE(PT_REGS_R28, offsetof(struct pt_regs, r28));
-	DEFINE(PT_REGS_TRAP_A0, offsetof(struct pt_regs, trap_a0));
-	DEFINE(PT_REGS_TRAP_A1, offsetof(struct pt_regs, trap_a1));
-	DEFINE(PT_REGS_TRAP_A2, offsetof(struct pt_regs, trap_a2));
 	DEFINE(PT_REGS_PS, offsetof(struct pt_regs, ps));
 	DEFINE(PT_REGS_PC, offsetof(struct pt_regs, pc));
 	DEFINE(PT_REGS_GP, offsetof(struct pt_regs, gp));

arch/sw_64/kernel/entry.S

@@ -14,11 +14,10 @@
 /*
  * This defines the normal kernel pt-regs layout.
  *
- * regs 9-15 preserved by C code
+ * regs 9-15 preserved by C code, saving to pt_regs will make
+ * them easier to be accessed in an unified way.
  * regs 16-18 saved by HMcode
  * regs 29-30 saved and set up by HMcode
- * JRP - Save regs 16-18 in a special area of the stack, so that
- * the hmcode-provided values are available to the signal handler.
  */
 
 	.macro SAVE_COMMON_REGS
@@ -42,9 +41,6 @@
 	stl	$25, PT_REGS_R25($sp)
 	stl	$26, PT_REGS_R26($sp)
 	stl	$27, PT_REGS_R27($sp)
-	stl	$16, PT_REGS_TRAP_A0($sp)
-	stl	$17, PT_REGS_TRAP_A1($sp)
-	stl	$18, PT_REGS_TRAP_A2($sp)
 	.endm
 
 	.macro RESTORE_COMMON_REGS

arch/sw_64/kernel/ptrace.c

@@ -504,10 +504,6 @@ static const struct pt_regs_offset regoffset_table[] = {
 	REG_OFFSET_NAME(r26),
 	REG_OFFSET_NAME(r27),
 	REG_OFFSET_NAME(r28),
-	REG_OFFSET_NAME(hae),
-	REG_OFFSET_NAME(trap_a0),
-	REG_OFFSET_NAME(trap_a1),
-	REG_OFFSET_NAME(trap_a2),
 	REG_OFFSET_NAME(ps),
 	REG_OFFSET_NAME(pc),
 	REG_OFFSET_NAME(gp),

arch/sw_64/kernel/signal.c

@@ -255,10 +255,6 @@ setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 				offsetof(struct user_fpsimd_state, fpcr));
 	err |= __put_user(current->thread.fpstate.fpcr, &sc->sc_fpcr);
 
-	err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
-	err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
-	err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
-
 	return err;
 }