LoongArch: extable: Add `type` and `data` fields

mainline inclusion
from mainline-v6.2-rc1
commit 26bc8244
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6BWFP
CVE: NA

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

This is a LoongArch port of commit d6e2cc56 ("arm64: extable: add
`type` and `data` fields").

Subsequent patches will add specialized handlers for fixups, in addition
to the simple PC fixup we have today. In preparation, this patch adds a
new `type` field to struct exception_table_entry, and uses this to
distinguish the fixup and other cases. A `data` field is also added so
that subsequent patches can associate data specific to each exception
site (e.g. register numbers).

Handlers are named ex_handler_*() for consistency, following the example
of x86. At the same time, get_ex_fixup() is split out into a helper so
that it can be used by other ex_handler_*() functions in the subsequent
patches.
Signed-off-by: NYouling Tang <tangyouling@loongson.cn>
Signed-off-by: NHuacai Chen <chenhuacai@loongson.cn>
Change-Id: I95ac7a755a8a3389b63b92c1e98a851c1993c0aa

arch/loongarch/include/asm/asm-extable.h

@@ -2,17 +2,22 @@
 #ifndef __ASM_ASM_EXTABLE_H
 #define __ASM_ASM_EXTABLE_H
 
+#define EX_TYPE_NONE			0
+#define EX_TYPE_FIXUP			1
+
 #ifdef __ASSEMBLY__
 
-#define __ASM_EXTABLE_RAW(insn, fixup)			\
+#define __ASM_EXTABLE_RAW(insn, fixup, type, data)	\
 	.pushsection	__ex_table, "a";		\
 	.balign		4;				\
 	.long		((insn) - .);			\
 	.long		((fixup) - .);			\
+	.short		(type);				\
+	.short		(data);				\
 	.popsection;
 
 	.macro		_asm_extable, insn, fixup
-	__ASM_EXTABLE_RAW(\insn, \fixup)
+	__ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_FIXUP, 0)
 	.endm
 
 #else /* __ASSEMBLY__ */
@@ -20,15 +25,17 @@
 #include <linux/bits.h>
 #include <linux/stringify.h>
 
-#define __ASM_EXTABLE_RAW(insn, fixup)			\
+#define __ASM_EXTABLE_RAW(insn, fixup, type, data)	\
 	".pushsection	__ex_table, \"a\"\n"		\
 	".balign	4\n"				\
 	".long		((" insn ") - .)\n"		\
 	".long		((" fixup ") - .)\n"		\
+	".short		(" type ")\n"			\
+	".short		(" data ")\n"			\
 	".popsection\n"
 
 #define _ASM_EXTABLE(insn, fixup)	\
-	__ASM_EXTABLE_RAW(#insn, #fixup)
+	__ASM_EXTABLE_RAW(#insn, #fixup, __stringify(EX_TYPE_FIXUP), "0")
 
 #endif /* __ASSEMBLY__ */
 

arch/loongarch/include/asm/extable.h

@@ -17,10 +17,21 @@
 
 struct exception_table_entry {
 	int insn, fixup;
+	short type, data;
 };
 
 #define ARCH_HAS_RELATIVE_EXTABLE
 
+#define swap_ex_entry_fixup(a, b, tmp, delta)		\
+do {							\
+	(a)->fixup = (b)->fixup + (delta);		\
+	(b)->fixup = (tmp).fixup - (delta);		\
+	(a)->type = (b)->type;				\
+	(b)->type = (tmp).type;				\
+	(a)->data = (b)->data;				\
+	(b)->data = (tmp).data;				\
+} while (0)
+
 bool fixup_exception(struct pt_regs *regs);
 
 #endif

arch/loongarch/kernel/vmlinux.lds.S

@@ -4,6 +4,7 @@
 #include <asm/thread_info.h>
 
 #define PAGE_SIZE _PAGE_SIZE
+#define RO_EXCEPTION_TABLE_ALIGN	4
 
 /*
  * Put .bss..swapper_pg_dir as the first thing in .bss. This will
@@ -53,8 +54,6 @@ SECTIONS
 	. = ALIGN(PECOFF_SEGMENT_ALIGN);
 	_etext = .;
 
-	EXCEPTION_TABLE(16)
-
 	. = ALIGN(PECOFF_SEGMENT_ALIGN);
 	__init_begin = .;
 	__inittext_begin = .;

arch/loongarch/mm/extable.c

@@ -30,5 +30,10 @@ bool fixup_exception(struct pt_regs *regs)
 	if (!ex)
 		return false;
 
-	return ex_handler_fixup(ex, regs);
+	switch (ex->type) {
+	case EX_TYPE_FIXUP:
+		return ex_handler_fixup(ex, regs);
+	}
+
+	BUG();
 }

scripts/sorttable.c

@@ -231,6 +231,34 @@ static void sort_relative_table(char *extab_image, int image_size)
 	}
 }
 
+static void sort_relative_table_with_data(char *extab_image, int image_size)
+{
+	int i = 0;
+
+	while (i < image_size) {
+		uint32_t *loc = (uint32_t *)(extab_image + i);
+
+		w(r(loc) + i, loc);
+		w(r(loc + 1) + i + 4, loc + 1);
+		/* Don't touch the fixup type or data */
+
+		i += sizeof(uint32_t) * 3;
+	}
+
+	qsort(extab_image, image_size / 12, 12, compare_relative_table);
+
+	i = 0;
+	while (i < image_size) {
+		uint32_t *loc = (uint32_t *)(extab_image + i);
+
+		w(r(loc) - i, loc);
+		w(r(loc + 1) - (i + 4), loc + 1);
+		/* Don't touch the fixup type or data */
+
+		i += sizeof(uint32_t) * 3;
+	}
+}
+
 static void x86_sort_relative_table(char *extab_image, int image_size)
 {
 	int i = 0;
@@ -339,6 +367,9 @@ static int do_file(char const *const fname, void *addr)
 	case EM_X86_64:
 		custom_sort = x86_sort_relative_table;
 		break;
+	case EM_LOONGARCH:
+		custom_sort = sort_relative_table_with_data;
+		break;
 	case EM_S390:
 		custom_sort = s390_sort_relative_table;
 		break;
@@ -347,7 +378,6 @@ static int do_file(char const *const fname, void *addr)
 	case EM_PPC:
 	case EM_ARM:
 	case EM_PPC64:
-	case EM_LOONGARCH:
 		custom_sort = sort_relative_table;
 		break;
 	case EM_ARCOMPACT: