Subject: [PATCH 09/12] riscv: extable: add `type` and `data` fields

From: Jisheng Zhang <[email-masked]>
Date: Thu, 18 Nov 2021 19:26:05 +0800

From: Jisheng Zhang <[email-masked]>

This is a riscv port of commit d6e2cc564775("arm64: extable: add `type`
and `data` fields").

We will add specialized handlers for fixups, the `type` field is for
fixup handler type, the `data` field is used to pass specific data to
each handler, for example register numbers.

Signed-off-by: Jisheng Zhang <[email-masked]>
---
 arch/riscv/include/asm/asm-extable.h | 25 +++++++++++++++++--------
 arch/riscv/include/asm/extable.h     | 17 ++++++++++++++---
 arch/riscv/kernel/vmlinux.lds.S      |  2 +-
 arch/riscv/mm/extable.c              | 25 +++++++++++++++++++++----
 arch/riscv/net/bpf_jit_comp64.c      |  5 +++--
 scripts/sorttable.c                  |  4 +++-
 6 files changed, 59 insertions(+), 19 deletions(-)

diff --git a/arch/riscv/include/asm/asm-extable.h b/arch/riscv/include/asm/asm-extable.h
index b790c02dbdda..1b1f4ffd8d37 100644
--- a/arch/riscv/include/asm/asm-extable.h
+++ b/arch/riscv/include/asm/asm-extable.h
@@ -2,31 +2,40 @@
 #ifndef __ASM_ASM_EXTABLE_H
 #define __ASM_ASM_EXTABLE_H
 
+#define EX_TYPE_NONE			0
+#define EX_TYPE_FIXUP			1
+#define EX_TYPE_BPF			2
+
 #ifdef __ASSEMBLY__
 
-#define __ASM_EXTABLE_RAW(insn, fixup)		\
-	.pushsection	__ex_table, "a";	\
-	.balign		4;			\
-	.long		((insn) - .);		\
-	.long		((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__ */
 
 #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)
+#define _ASM_EXTABLE(insn, fixup)	\
+	__ASM_EXTABLE_RAW(#insn, #fixup, __stringify(EX_TYPE_FIXUP), "0")
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/riscv/include/asm/extable.h b/arch/riscv/include/asm/extable.h
index e4374dde02b4..512012d193dc 100644
--- a/arch/riscv/include/asm/extable.h
+++ b/arch/riscv/include/asm/extable.h
@@ -17,18 +17,29 @@
 
 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);
 
 #if defined(CONFIG_BPF_JIT) && defined(CONFIG_ARCH_RV64I)
-bool rv_bpf_fixup_exception(const struct exception_table_entry *ex, struct pt_regs *regs);
+bool ex_handler_bpf(const struct exception_table_entry *ex, struct pt_regs *regs);
 #else
 static inline bool
-rv_bpf_fixup_exception(const struct exception_table_entry *ex,
-		       struct pt_regs *regs)
+ex_handler_bpf(const struct exception_table_entry *ex,
+	       struct pt_regs *regs)
 {
 	return false;
 }
diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 5104f3a871e3..0e5ae851929e 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -4,7 +4,7 @@
  * Copyright (C) 2017 SiFive
  */
 
-#define RO_EXCEPTION_TABLE_ALIGN	16
+#define RO_EXCEPTION_TABLE_ALIGN	4
 
 #ifdef CONFIG_XIP_KERNEL
 #include "vmlinux-xip.lds.S"
diff --git a/arch/riscv/mm/extable.c b/arch/riscv/mm/extable.c
index 3c561f1d0115..91e52c4bb33a 100644
--- a/arch/riscv/mm/extable.c
+++ b/arch/riscv/mm/extable.c
@@ -10,6 +10,20 @@
 #include <linux/extable.h>
 #include <linux/module.h>
 #include <linux/uaccess.h>
+#include <asm/asm-extable.h>
+
+static inline unsigned long
+get_ex_fixup(const struct exception_table_entry *ex)
+{
+	return ((unsigned long)&ex->fixup + ex->fixup);
+}
+
+static bool ex_handler_fixup(const struct exception_table_entry *ex,
+			     struct pt_regs *regs)
+{
+	regs->epc = get_ex_fixup(ex);
+	return true;
+}
 
 bool fixup_exception(struct pt_regs *regs)
 {
@@ -19,9 +33,12 @@ bool fixup_exception(struct pt_regs *regs)
 	if (!ex)
 		return false;
 
-	if (regs->epc >= BPF_JIT_REGION_START && regs->epc < BPF_JIT_REGION_END)
-		return rv_bpf_fixup_exception(ex, regs);
+	switch (ex->type) {
+	case EX_TYPE_FIXUP:
+		return ex_handler_fixup(ex, regs);
+	case EX_TYPE_BPF:
+		return ex_handler_bpf(ex, regs);
+	}
 
-	regs->epc = (unsigned long)&ex->fixup + ex->fixup;
-	return true;
+	BUG();
 }
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index 7714081cbb64..69bab7e28f91 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -459,8 +459,8 @@ static int emit_call(bool fixed, u64 addr, struct rv_jit_context *ctx)
 #define BPF_FIXUP_OFFSET_MASK   GENMASK(26, 0)
 #define BPF_FIXUP_REG_MASK      GENMASK(31, 27)
 
-bool rv_bpf_fixup_exception(const struct exception_table_entry *ex,
-			    struct pt_regs *regs)
+bool ex_handler_bpf(const struct exception_table_entry *ex,
+		    struct pt_regs *regs)
 {
 	off_t offset = FIELD_GET(BPF_FIXUP_OFFSET_MASK, ex->fixup);
 	int regs_offset = FIELD_GET(BPF_FIXUP_REG_MASK, ex->fixup);
@@ -514,6 +514,7 @@ static int add_exception_handler(const struct bpf_insn *insn,
 
 	ex->fixup = FIELD_PREP(BPF_FIXUP_OFFSET_MASK, offset) |
 		FIELD_PREP(BPF_FIXUP_REG_MASK, dst_reg);
+	ex->type = EX_TYPE_BPF;
 
 	ctx->nexentries++;
 	return 0;
diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index 0c031e47a419..5b5472b543f5 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -376,9 +376,11 @@ static int do_file(char const *const fname, void *addr)
 	case EM_PARISC:
 	case EM_PPC:
 	case EM_PPC64:
-	case EM_RISCV:
 		custom_sort = sort_relative_table;
 		break;
+	case EM_RISCV:
+		custom_sort = arm64_sort_relative_table;
+		break;
 	case EM_ARCOMPACT:
 	case EM_ARCV2:
 	case EM_ARM:
-- 
2.33.0