On Wed, Apr 06, 2022 at 09:13:08AM +0000, Tong Tiangen wrote: > Add scenarios copy_from_user to machine check safe. > > The data copied is user data and is machine check safe, so just kill > the user process and isolate the error page, not necessary panic. > > Signed-off-by: Tong Tiangen <tongtiangen@xxxxxxxxxx> > --- > arch/arm64/include/asm/asm-uaccess.h | 16 ++++++++++++++++ > arch/arm64/lib/copy_from_user.S | 11 ++++++----- > 2 files changed, 22 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h > index 0557af834e03..f31c8978e1af 100644 > --- a/arch/arm64/include/asm/asm-uaccess.h > +++ b/arch/arm64/include/asm/asm-uaccess.h > @@ -92,4 +92,20 @@ alternative_else_nop_endif > > _asm_extable 8888b,\l; > .endm > + > + .macro user_ldp_mc l, reg1, reg2, addr, post_inc > +8888: ldtr \reg1, [\addr]; > +8889: ldtr \reg2, [\addr, #8]; > + add \addr, \addr, \post_inc; > + > + _asm_extable_mc 8888b, \l; > + _asm_extable_mc 8889b, \l; > + .endm > + > + .macro user_ldst_mc l, inst, reg, addr, post_inc > +8888: \inst \reg, [\addr]; > + add \addr, \addr, \post_inc; > + > + _asm_extable_mc 8888b, \l; > + .endm > #endif > diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S > index 34e317907524..d9d7c5291871 100644 > --- a/arch/arm64/lib/copy_from_user.S > +++ b/arch/arm64/lib/copy_from_user.S > @@ -21,7 +21,7 @@ > */ > > .macro ldrb1 reg, ptr, val > - user_ldst 9998f, ldtrb, \reg, \ptr, \val > + user_ldst_mc 9998f, ldtrb, \reg, \ptr, \val > .endm > > .macro strb1 reg, ptr, val > @@ -29,7 +29,7 @@ > .endm > > .macro ldrh1 reg, ptr, val > - user_ldst 9997f, ldtrh, \reg, \ptr, \val > + user_ldst_mc 9997f, ldtrh, \reg, \ptr, \val > .endm > > .macro strh1 reg, ptr, val > @@ -37,7 +37,7 @@ > .endm > > .macro ldr1 reg, ptr, val > - user_ldst 9997f, ldtr, \reg, \ptr, \val > + user_ldst_mc 9997f, ldtr, \reg, \ptr, \val > .endm > > .macro str1 reg, ptr, val > @@ -45,7 +45,7 @@ > .endm > > .macro ldp1 reg1, reg2, ptr, val > - user_ldp 9997f, \reg1, \reg2, \ptr, \val > + user_ldp_mc 9997f, \reg1, \reg2, \ptr, \val > .endm > > .macro stp1 reg1, reg2, ptr, val > @@ -62,7 +62,8 @@ SYM_FUNC_START(__arch_copy_from_user) > ret > > // Exception fixups > -9997: cmp dst, dstin > +9997: cbz x0, 9998f // Check machine check exception > + cmp dst, dstin > b.ne 9998f If you look at the copy template, you'd see that `dstin` *is* x0. Consier if we took a non-SEA fault. The the fixup handler will overwrite x0, it's likely `dst` != `dstin`, and we'll branch to the byte-by-byte copy. Or if we're doing something odd and mmap_min_addr is 0, we can do the wrong thing the other way around and *not* branch to the byte-by-byte copy when we should. So this is at best confusing, but likely broken too. Thanks, Mark. > // Before being absolutely sure we couldn't copy anything, try harder > USER(9998f, ldtrb tmp1w, [srcin]) > -- > 2.18.0.huawei.25 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
