sw64: perf: don't rely on layout of pt_regs to grab some registers

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6ILAC

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

The layout of struct perf_event_sw64_regs and pt_regs is inconsistent,
and some integer registers cannot get correct value.

This patch checks these registers explicitly to return the appropriate
values.
Signed-off-by: NHe Chuyue <hechuyue@wxiat.com>
Reviewed-by: NHe Sheng <hesheng@wxiat.com>
Signed-off-by: NGu Zitao <guzitao@wxiat.com>

arch/sw_64/kernel/perf_regs.c

@@ -8,7 +8,24 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
 	if (WARN_ON_ONCE((u32)idx >= PERF_REG_SW64_MAX))
 		return 0;
 
-	return ((unsigned long *)regs)[idx];
+	switch (idx) {
+	case PERF_REG_SW64_R16:
+		return regs->r16;
+	case PERF_REG_SW64_R17:
+		return regs->r17;
+	case PERF_REG_SW64_R18:
+		return regs->r18;
+	case PERF_REG_SW64_R19 ... PERF_REG_SW64_R28:
+		return ((unsigned long *)regs)[idx - 3];
+	case PERF_REG_SW64_GP:
+		return regs->gp;
+	case PERF_REG_SW64_SP:
+		return (u64)(user_mode(regs) ? rdusp() : (regs + 1));
+	case PERF_REG_SW64_PC:
+		return regs->pc;
+	default:
+		return ((unsigned long *)regs)[idx];
+	}
 }
 
 #define REG_RESERVED (~((1ULL << PERF_REG_SW64_MAX) - 1))