[PATCH -next v5 2/8] arm64: extable: make uaaccess helper use extable type EX_TYPE_UACCESS_ERR_ZERO

Tong Tiangen
2022-05-28T06:32:21Z

Currnetly, the extable type used by __arch_copy_from/to_user() is
EX_TYPE_FIXUP. In fact, It is more clearly to use meaningful
EX_TYPE_UACCESS_*.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
---
arch/arm64/include/asm/asm-extable.h | 8 ++++++++
arch/arm64/include/asm/asm-uaccess.h | 12 ++++++------
2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h
index 56ebe183e78b..9c94ac1f082c 100644
--- a/arch/arm64/include/asm/asm-extable.h
+++ b/arch/arm64/include/asm/asm-extable.h
@@ -28,6 +28,14 @@
__ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_FIXUP, 0)
.endm

+/*
+ * Create an exception table entry for uaccess `insn`, which will branch to `fixup`
+ * when an unhandled fault is taken.
+ * ex->data = ~0 means both reg_err and reg_zero is set to wzr(x31).
+ */
+ .macro _asm_extable_uaccess, insn, fixup
+ __ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_UACCESS_ERR_ZERO, ~0)
+ .endm
/*
* Create an exception table entry for `insn` if `fixup` is provided. Otherwise
* do nothing.
diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
index 0557af834e03..75b211c98dea 100644
--- a/arch/arm64/include/asm/asm-uaccess.h
+++ b/arch/arm64/include/asm/asm-uaccess.h
@@ -61,7 +61,7 @@ alternative_else_nop_endif

#define USER(l, x...) \
9999: x; \
- _asm_extable 9999b, l
+ _asm_extable_uaccess 9999b, l

/*
* Generate the assembly for LDTR/STTR with exception table entries.
@@ -73,8 +73,8 @@ alternative_else_nop_endif
8889: ldtr \reg2, [\addr, #8];
add \addr, \addr, \post_inc;

- _asm_extable 8888b,\l;
- _asm_extable 8889b,\l;
+ _asm_extable_uaccess 8888b, \l;
+ _asm_extable_uaccess 8889b, \l;
.endm

.macro user_stp l, reg1, reg2, addr, post_inc
@@ -82,14 +82,14 @@ alternative_else_nop_endif
8889: sttr \reg2, [\addr, #8];
add \addr, \addr, \post_inc;

- _asm_extable 8888b,\l;
- _asm_extable 8889b,\l;
+ _asm_extable_uaccess 8888b,\l;
+ _asm_extable_uaccess 8889b,\l;
.endm

.macro user_ldst l, inst, reg, addr, post_inc
8888: \inst \reg, [\addr];
add \addr, \addr, \post_inc;

- _asm_extable 8888b,\l;
+ _asm_extable_uaccess 8888b, \l;
.endm
#endif
--
2.25.1