在 2022/6/18 11:26, Tong Tiangen 写道:
在 2022/6/17 16:24, Mark Rutland 写道:On Sat, May 28, 2022 at 06:50:50AM +0000, Tong Tiangen wrote: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@xxxxxxx> Signed-off-by: Tong Tiangen <tongtiangen@xxxxxxxxxx> --- 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.hindex 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) + .endmI'm not too keen on using `~0` here, since that also sets other bits in thedata field, and its somewhat opaque.How painful is it to generate the data fields as with the C version of thismacro, so that we can pass in wzr explciitly for the two sub-fields? Other than that, this looks good to me. Thanks, Mark.ok, will fix next version. Thanks, Tong.
I tried to using data filelds as with C version, but here assembly code we can not using operator such as << and |, if we use lsl and orr instructions, the gpr will be occupied.
So how about using 0x3ff directly here? it means err register and zero register both set to x31.
Thanks, Tong.
/** 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.hindex 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._______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-arm-kernel