| Message ID | 20191018161033.261971-2-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | add support for Clang's Shadow Call Stack | expand |
On Fri, Oct 18, 2019 at 9:10 AM Sami Tolvanen <samitolvanen@google.com> wrote: > > idmap_kpti_install_ng_mappings uses x18 as a temporary register, which > will result in a conflict when x18 is reserved. Use x16 and x17 instead > where needed. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> TIL about .req/.unreq. Seems like a nice way of marking "variable" lifetime. Technically, only `pte` needed to be moved to reuse {w|x}16, but moving most the unreqs together is nicer than splitting them apart. The usage all looks correct to me. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > --- > arch/arm64/mm/proc.S | 63 ++++++++++++++++++++++---------------------- > 1 file changed, 32 insertions(+), 31 deletions(-) > > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index a1e0592d1fbc..fdabf40a83c8 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -250,15 +250,15 @@ ENTRY(idmap_kpti_install_ng_mappings) > /* We're the boot CPU. Wait for the others to catch up */ > sevl > 1: wfe > - ldaxr w18, [flag_ptr] > - eor w18, w18, num_cpus > - cbnz w18, 1b > + ldaxr w17, [flag_ptr] > + eor w17, w17, num_cpus > + cbnz w17, 1b > > /* We need to walk swapper, so turn off the MMU. */ > pre_disable_mmu_workaround > - mrs x18, sctlr_el1 > - bic x18, x18, #SCTLR_ELx_M > - msr sctlr_el1, x18 > + mrs x17, sctlr_el1 > + bic x17, x17, #SCTLR_ELx_M > + msr sctlr_el1, x17 > isb > > /* Everybody is enjoying the idmap, so we can rewrite swapper. */ > @@ -281,9 +281,9 @@ skip_pgd: > isb > > /* We're done: fire up the MMU again */ > - mrs x18, sctlr_el1 > - orr x18, x18, #SCTLR_ELx_M > - msr sctlr_el1, x18 > + mrs x17, sctlr_el1 > + orr x17, x17, #SCTLR_ELx_M > + msr sctlr_el1, x17 > isb > > /* > @@ -353,46 +353,47 @@ skip_pte: > b.ne do_pte > b next_pmd > > + .unreq cpu > + .unreq num_cpus > + .unreq swapper_pa > + .unreq cur_pgdp > + .unreq end_pgdp > + .unreq pgd > + .unreq cur_pudp > + .unreq end_pudp > + .unreq pud > + .unreq cur_pmdp > + .unreq end_pmdp > + .unreq pmd > + .unreq cur_ptep > + .unreq end_ptep > + .unreq pte > + > /* Secondary CPUs end up here */ > __idmap_kpti_secondary: > /* Uninstall swapper before surgery begins */ > - __idmap_cpu_set_reserved_ttbr1 x18, x17 > + __idmap_cpu_set_reserved_ttbr1 x16, x17 > > /* Increment the flag to let the boot CPU we're ready */ > -1: ldxr w18, [flag_ptr] > - add w18, w18, #1 > - stxr w17, w18, [flag_ptr] > +1: ldxr w16, [flag_ptr] > + add w16, w16, #1 > + stxr w17, w16, [flag_ptr] > cbnz w17, 1b > > /* Wait for the boot CPU to finish messing around with swapper */ > sevl > 1: wfe > - ldxr w18, [flag_ptr] > - cbnz w18, 1b > + ldxr w16, [flag_ptr] > + cbnz w16, 1b > > /* All done, act like nothing happened */ > - offset_ttbr1 swapper_ttb, x18 > + offset_ttbr1 swapper_ttb, x16 > msr ttbr1_el1, swapper_ttb > isb > ret > > - .unreq cpu > - .unreq num_cpus > - .unreq swapper_pa > .unreq swapper_ttb > .unreq flag_ptr > - .unreq cur_pgdp > - .unreq end_pgdp > - .unreq pgd > - .unreq cur_pudp > - .unreq end_pudp > - .unreq pud > - .unreq cur_pmdp > - .unreq end_pmdp > - .unreq pmd > - .unreq cur_ptep > - .unreq end_ptep > - .unreq pte > ENDPROC(idmap_kpti_install_ng_mappings) > .popsection > #endif > -- > 2.23.0.866.gb869b98d4c-goog >
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index a1e0592d1fbc..fdabf40a83c8 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -250,15 +250,15 @@ ENTRY(idmap_kpti_install_ng_mappings) /* We're the boot CPU. Wait for the others to catch up */ sevl 1: wfe - ldaxr w18, [flag_ptr] - eor w18, w18, num_cpus - cbnz w18, 1b + ldaxr w17, [flag_ptr] + eor w17, w17, num_cpus + cbnz w17, 1b /* We need to walk swapper, so turn off the MMU. */ pre_disable_mmu_workaround - mrs x18, sctlr_el1 - bic x18, x18, #SCTLR_ELx_M - msr sctlr_el1, x18 + mrs x17, sctlr_el1 + bic x17, x17, #SCTLR_ELx_M + msr sctlr_el1, x17 isb /* Everybody is enjoying the idmap, so we can rewrite swapper. */ @@ -281,9 +281,9 @@ skip_pgd: isb /* We're done: fire up the MMU again */ - mrs x18, sctlr_el1 - orr x18, x18, #SCTLR_ELx_M - msr sctlr_el1, x18 + mrs x17, sctlr_el1 + orr x17, x17, #SCTLR_ELx_M + msr sctlr_el1, x17 isb /* @@ -353,46 +353,47 @@ skip_pte: b.ne do_pte b next_pmd + .unreq cpu + .unreq num_cpus + .unreq swapper_pa + .unreq cur_pgdp + .unreq end_pgdp + .unreq pgd + .unreq cur_pudp + .unreq end_pudp + .unreq pud + .unreq cur_pmdp + .unreq end_pmdp + .unreq pmd + .unreq cur_ptep + .unreq end_ptep + .unreq pte + /* Secondary CPUs end up here */ __idmap_kpti_secondary: /* Uninstall swapper before surgery begins */ - __idmap_cpu_set_reserved_ttbr1 x18, x17 + __idmap_cpu_set_reserved_ttbr1 x16, x17 /* Increment the flag to let the boot CPU we're ready */ -1: ldxr w18, [flag_ptr] - add w18, w18, #1 - stxr w17, w18, [flag_ptr] +1: ldxr w16, [flag_ptr] + add w16, w16, #1 + stxr w17, w16, [flag_ptr] cbnz w17, 1b /* Wait for the boot CPU to finish messing around with swapper */ sevl 1: wfe - ldxr w18, [flag_ptr] - cbnz w18, 1b + ldxr w16, [flag_ptr] + cbnz w16, 1b /* All done, act like nothing happened */ - offset_ttbr1 swapper_ttb, x18 + offset_ttbr1 swapper_ttb, x16 msr ttbr1_el1, swapper_ttb isb ret - .unreq cpu - .unreq num_cpus - .unreq swapper_pa .unreq swapper_ttb .unreq flag_ptr - .unreq cur_pgdp - .unreq end_pgdp - .unreq pgd - .unreq cur_pudp - .unreq end_pudp - .unreq pud - .unreq cur_pmdp - .unreq end_pmdp - .unreq pmd - .unreq cur_ptep - .unreq end_ptep - .unreq pte ENDPROC(idmap_kpti_install_ng_mappings) .popsection #endif
idmap_kpti_install_ng_mappings uses x18 as a temporary register, which will result in a conflict when x18 is reserved. Use x16 and x17 instead where needed. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- arch/arm64/mm/proc.S | 63 ++++++++++++++++++++++---------------------- 1 file changed, 32 insertions(+), 31 deletions(-)