kpatch/LoongArch: process section __patchable_function_entries

Generate 2 NOPs right at the beginning of each function with
-fpatchable-function-entry=2 in LoongArch. Here process the situation.

Co-developed-by: zhanghongchen <[email protected]>
Signed-off-by: George Guo <[email protected]>

Author: georgejguo

kpatch-build/create-diff-object.c

@@ -3838,6 +3838,20 @@ static void kpatch_create_ftrace_callsite_sections(struct kpatch_elf *kelf, bool
 			insn_offset = sym->sym.st_value;
 			break;
 		}
+		case LOONGARCH64: {
+#define LOONGARCH_NOP 0x03400000
+			bool found = false;
+			unsigned int *insn = sym->sec->data->d_buf + sym->sym.st_value;
+
+			if (*insn == LOONGARCH_NOP && *(insn + 1) == LOONGARCH_NOP)
+				found = true;
+
+			if (!found)
+				ERROR("%s: unexpected instruction at the start of the function", sym->name);
+
+			insn_offset = 0;
+			break;
+		}
 		default:
 			ERROR("unsupported arch");
 		}
@@ -4088,6 +4102,23 @@ static void kpatch_find_func_profiling_calls(struct kpatch_elf *kelf)
 				insn[4] == 0x00 && insn[5] == 0x00)
 				sym->has_func_profiling = 1;
 			break;
+		case LOONGARCH64:
+			struct section *sec;
+
+			sec = find_section_by_name(&kelf->sections,
+					"__patchable_function_entries");
+			if (sec) {
+				list_for_each_entry(rela, &sec->rela->relas, list) {
+					if (rela->sym->sec == sym->sec &&
+					   (rela->sym->sym.st_value +
+					   rela->addend) == sym->sym.st_value) {
+						sym->has_func_profiling = 1;
+						break;
+					}
+				}
+			}
+			break;
+
 		default:
 			ERROR("unsupported arch");
 		}