Re: [PATCH v6 00/14] riscv: support for Svpbmt and D1 memory types
From: Atish Patra
Date: Fri Feb 11 2022 - 19:26:13 EST
On Thu, Feb 10, 2022 at 6:04 PM Heiko Stübner <heiko@xxxxxxxxx> wrote:
>
> Am Freitag, 11. Februar 2022, 02:48:38 CET schrieb Atish Patra:
> > On Thu, Feb 10, 2022 at 4:25 PM Atish Patra <atishp@xxxxxxxxxxxxxx> wrote:
> > >
> > > On Wed, Feb 9, 2022 at 4:38 AM Heiko Stuebner <heiko@xxxxxxxxx> wrote:
> > > >
> > > > Svpbmt is an extension defining "Supervisor-mode: page-based memory types"
> > > > for things like non-cacheable pages or I/O memory pages.
> > > >
> > > >
> > > > So this is my 2nd try at implementing Svpbmt (and the diverging D1 memory
> > > > types) using the alternatives framework.
> > > >
> > > > This includes a number of changes to the alternatives mechanism itself.
> > > > The biggest one being the move to a more central location, as I expect
> > > > in the future, nearly every chip needing some sort of patching, be it
> > > > either for erratas or for optional features (svpbmt or others).
> > > >
> > > > The dt-binding for svpbmt itself is of course not finished and is still
> > > > using the binding introduced in previous versions, as where to put
> > > > a svpbmt-property in the devicetree is still under dicussion.
> > > > Atish seems to be working on a framework for extensions [0],
> > > >
> > >
> > > Here is the patch series
> > > https://lore.kernel.org/lkml/20220210214018.55739-1-atishp@xxxxxxxxxxxx/
> > >
> > > I think we can simplify the cpu feature probing in PATCH 10 with the
> > > above series
> > > which simply relies on the existing riscv_isa bitmap.
> > >
> > > We also don't need the separate svpbmt property in DT mmu node.
> > > Let me know what you think.
> > >
> > > > The series also introduces support for the memory types of the D1
> > > > which are implemented differently to svpbmt. But when patching anyway
> > > > it's pretty clean to add the D1 variant via ALTERNATIVE_2 to the same
> > > > location.
> > > >
> > > > The only slightly bigger difference is that the "normal" type is not 0
> > > > as with svpbmt, so kernel patches for this PMA type need to be applied
> > > > even before the MMU is brought up, so the series introduces a separate
> > > > stage for that.
> > > >
> > > >
> > > > In theory this series is 3 parts:
> > > > - sbi cache-flush / null-ptr
> > > > - alternatives improvements
> > > > - svpbmt+d1
> > > >
> > > > So expecially patches from the first 2 areas could be applied when
> > > > deemed ready, I just thought to keep it together to show-case where
> > > > the end-goal is and not requiring jumping between different series.
> > > >
> > > >
> > > > The sbi cache-flush patch is based on Atish's sparse-hartid patch [1],
> > > > as it touches a similar area in mm/cacheflush.c
> > > >
> > > >
> > > > I picked the recipient list from the previous version, hopefully
> > > > I didn't forget anybody.
> > > >
> >
> > I am also getting a load access fault while booting this series in Qemu.
> >
> > <with additional debug message when before sbi_trap_redirect in OpenSBI>
> > sbi_trap_error_debug: hart1: trap handler failed (error -2)
> > sbi_trap_error_debug: hart1: mcause=0x0000000000000005 mtval=0x0000000080046468
> > sbi_trap_error_debug: hart1: mtval2=0x0000000000000000 mtinst=0x0000000000000000
> > sbi_trap_error_debug: hart1: mepc=0x000000008080a8b8 mstatus=0x0000000a00000800
> > sbi_trap_error_debug: hart1: ra=0x0000000080202b06 sp=0x0000000081203f00
> > sbi_trap_error_debug: hart1: gp=0x00000000812d9db8 tp=0x0000000080046000
> > sbi_trap_error_debug: hart1: s0=0x0000000081203f80 s1=0x0000000080c1a8a8
> > sbi_trap_error_debug: hart1: a0=0x0000000080c1a8a8 a1=0x0000000080c1b0d0
> > sbi_trap_error_debug: hart1: a2=0x0000000000000002 a3=0x0000000000000000
> > sbi_trap_error_debug: hart1: a4=0x00000000812da902 a5=0x0000000000000000
> > sbi_trap_error_debug: hart1: a6=0x0000000000000006 a7=0x0000000000000010
> > sbi_trap_error_debug: hart1: s2=0x0000000080c1b0d0 s3=0x0000000000000002
> > sbi_trap_error_debug: hart1: s4=0x00000000bf000000 s5=0x0000000000000000
> > sbi_trap_error_debug: hart1: s6=0x8000000a00006800 s7=0x000000000000007f
> > sbi_trap_error_debug: hart1: s8=0x0000000080018038 s9=0x0000000080039eac
> > sbi_trap_error_debug: hart1: s10=0x0000000000000000 s11=0x0000000000000000
> > sbi_trap_error_debug: hart1: t0=0x0000000080c04000 t1=0x0000000000000002
> > sbi_trap_error_debug: hart1: t2=0x0000000000001000 t3=0x0000000000000010
> > sbi_trap_error_debug: hart1: t4=0x00000000800168be t5=0x0000000000000027
> > sbi_trap_error_debug: hart1: t6=0x0000000000000001
> >
> > mepc : 0x000000008080a8b8 - call_function_init (kernel/smp.c)
> >
> > Kernel - 5.17-rc2 + my patches
> > Qemu - Alistairs next tree + my patches
>
> very strange. I was testing of course with Qemu as well, though never saw
> anything like this.
>
> But of course it was Qemu master + the then still pending svpbmt patchset [0]
> [looks like Alistair applied this today] + a patch that made qemu insert the
> svpbmt dt-property for the virt machine.
>
> Oh ... just to make sure, did you enable the svpbmt parameter when starting
> Qemu? (-cpu ...,svpbmt=true)
>
Yeah. I tried with or without. It's failing in both cases. I found a
fix but that may be unrelated and hiding the real issue.
Marking the cpufeature_svpbmt_check_of functions inline allows me to boot.
Here is my analysis:
Here is the trace of the trap:
sbi_trap_error_debug: hart0: trap handler failed (error -2)
sbi_trap_error_debug: hart0: mcause=0x0000000000000005 mtval=0x0000000080048468
sbi_trap_error_debug: hart0: mtval2=0x0000000000000000 mtinst=0x0000000000000000
sbi_trap_error_debug: hart0: mepc=0x000000008080a8b8 mstatus=0x0000000a00000800
sbi_trap_error_debug: hart0: ra=0x0000000080202b06 sp=0x0000000081203f00
sbi_trap_error_debug: hart0: gp=0x00000000812d9db8 tp=0x0000000080048000
sbi_trap_error_debug: hart0: s0=0x0000000081203f80 s1=0x0000000080c1a8a8
sbi_trap_error_debug: hart0: a0=0x0000000080c1a8a8 a1=0x0000000080c1b0d0
sbi_trap_error_debug: hart0: a2=0x0000000000000002 a3=0x0000000000000000
sbi_trap_error_debug: hart0: a4=0x00000000812da902 a5=0x0000000000000000
sbi_trap_error_debug: hart0: a6=0x0000000000000006 a7=0x0000000000000010
sbi_trap_error_debug: hart0: s2=0x0000000080c1b0d0 s3=0x0000000000000002
sbi_trap_error_debug: hart0: s4=0x00000000bf000000 s5=0x0000000000000000
sbi_trap_error_debug: hart0: s6=0x8000000a00006800 s7=0x000000000000007f
sbi_trap_error_debug: hart0: s8=0x0000000080018038 s9=0x0000000080039ea8
sbi_trap_error_debug: hart0: s10=0x0000000000000000 s11=0x0000000000000000
sbi_trap_error_debug: hart0: t0=0x0000000080c04000 t1=0x0000000000000002
sbi_trap_error_debug: hart0: t2=0x0000000000001000 t3=0x0000000000000010
sbi_trap_error_debug: hart0: t4=0x00000000800168be t5=0x0000000000000027
sbi_trap_error_debug: hart0: t6=0x0000000000000001
mepc : 0x000000008080a8b8 - should be ffffffff8060a8b8 in objdump
output after offset
Here is the snippet of the objdump output for riscv_cpufeature_patch_func
========================================================================
inline output: (booting fails with above dump)
void riscv_cpufeature_patch_func(struct alt_entry *begin, struct alt_entry *end,
unsigned int stage)
{
ffffffff8060a89a: 7119 addi sp,sp,-128
ffffffff8060a89c: f8a2 sd s0,112(sp)
ffffffff8060a89e: f4a6 sd s1,104(sp)
ffffffff8060a8a0: f0ca sd s2,96(sp)
ffffffff8060a8a2: e4d6 sd s5,72(sp)
ffffffff8060a8a4: fc86 sd ra,120(sp)
ffffffff8060a8a6: ecce sd s3,88(sp)
ffffffff8060a8a8: e8d2 sd s4,80(sp)
ffffffff8060a8aa: e0da sd s6,64(sp)
ffffffff8060a8ac: fc5e sd s7,56(sp)
ffffffff8060a8ae: f862 sd s8,48(sp)
ffffffff8060a8b0: f466 sd s9,40(sp)
ffffffff8060a8b2: f06a sd s10,32(sp)
ffffffff8060a8b4: ec6e sd s11,24(sp)
ffffffff8060a8b6: 0100 addi s0,sp,128
ffffffff8060a8b8: 46823783 ld a5,1128(tp) #
468 <__efistub_.L0 +0x5> --------> Faulting instruction
ffffffff8060a8bc: f8f43423 sd a5,-120(s0)
ffffffff8060a8c0: 4781 li a5,0
ffffffff8060a8c2: 8932 mv s2,a2
ffffffff8060a8c4: 84aa mv s1,a0
ffffffff8060a8c6: 8aae mv s5,a1
switch (stage) {
ffffffff8060a8c8: ca1d beqz
a2,ffffffff8060a8fe <riscv_cpufeature_patch_func+0x64>
ffffffff8060a8ca: 4789 li a5,2
ffffffff8060a8cc: 18f60363 beq
a2,a5,ffffffff8060aa52 <riscv_cpufeature_patch_func+0x1b8>
for_each_of_cpu_node(node) {
ffffffff8060a8d0: 4501 li a0,0
========================================================================
noinline output (boots fine)
========================================================================
void riscv_cpufeature_patch_func(struct alt_entry *begin, struct alt_entry *end,
unsigned int stage)
{
ffffffff8060a968: 7159 addi sp,sp,-112
ffffffff8060a96a: f0a2 sd s0,96(sp)
ffffffff8060a96c: eca6 sd s1,88(sp)
ffffffff8060a96e: e8ca sd s2,80(sp)
ffffffff8060a970: fc56 sd s5,56(sp)
ffffffff8060a972: f486 sd ra,104(sp)
ffffffff8060a974: e4ce sd s3,72(sp)
ffffffff8060a976: e0d2 sd s4,64(sp)
ffffffff8060a978: f85a sd s6,48(sp)
ffffffff8060a97a: f45e sd s7,40(sp)
ffffffff8060a97c: f062 sd s8,32(sp)
ffffffff8060a97e: ec66 sd s9,24(sp)
ffffffff8060a980: e86a sd s10,16(sp)
ffffffff8060a982: e46e sd s11,8(sp)
ffffffff8060a984: 1880 addi s0,sp,112
ffffffff8060a986: 8932 mv s2,a2
ffffffff8060a988: 84aa mv s1,a0
ffffffff8060a98a: 8aae mv s5,a1
switch (stage) {
ffffffff8060a98c: ca09 beqz
a2,ffffffff8060a99e <riscv_cpufeature_patch_func+0x36>
ffffffff8060a98e: 4789 li a5,2
ffffffff8060a990: 0ef60f63 beq
a2,a5,ffffffff8060aa8e <riscv_cpufeature_patch_func+0x126>
return cpufeature_svpbmt_check_of();
ffffffff8060a994: f07ff0ef jal
ra,ffffffff8060a89a <cpufeature_svpbmt_check_of>
cpu_req_feature |= (1U << idx);
ffffffff8060a998: 0005091b sext.w s2,a0
ffffffff8060a99c: a8d5 j
ffffffff8060aa90 <riscv_cpufeature_patch_func+0x128>
const void *fdt = dtb_early_va;
Any thoughts ? It looks like it may related to "tp"
>
> Heiko
>
> [0] http://lore.kernel.org/r/20220204022658.18097-1-liweiwei@xxxxxxxxxxx
>
>
> > I do have some out-of-tree patches but that shouldn't be an issue as I
> > am able to boot without your patches.
> > Commenting the *_boot_alternatives at both the places works fine as well.
> >
> > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> > index 0e1bb97f9749..bdeb7ab3e719 100644
> > --- a/arch/riscv/kernel/head.S
> > +++ b/arch/riscv/kernel/head.S
> > @@ -342,7 +342,7 @@ clear_bss_done:
> > call kasan_early_init
> > #endif
> > /* Start the kernel */
> > - call apply_boot_alternatives
> > + //call apply_boot_alternatives
> > call soc_early_init
> > tail start_kernel
> >
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index 7216db5d6a2c..c6bf8f4d3d16 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -819,7 +819,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> > BUG_ON((kernel_map.virt_addr + kernel_map.size) >
> > ADDRESS_SPACE_END - SZ_4K);
> > #endif
> >
> > - apply_early_boot_alternatives();
> > + //apply_early_boot_alternatives();
> > pt_ops_set_early();
> >
> > /* Setup early PGD for fixmap */
> >
> > I am currently debugging it and will let you know if I find the root cause.
> >
> > > > changes in v6:
> > > > - rebase onto 5.17-rc1
> > > > - handle sbi null-ptr differently
> > > > - improve commit messages
> > > > - use riscv,mmu as property name
> > > >
> > > > changes in v5:
> > > > - move to use alternatives for runtime-patching
> > > > - add D1 variant
> > > >
> > > >
> > > > [0] https://lore.kernel.org/r/20211224211632.1698523-1-atishp@xxxxxxxxxxxx
> > > > [1] https://lore.kernel.org/r/20220120090918.2646626-1-atishp@xxxxxxxxxxxx
> > > >
> > > >
> > > > Heiko Stuebner (12):
> > > > riscv: prevent null-pointer dereference with sbi_remote_fence_i
> > > > riscv: integrate alternatives better into the main architecture
> > > > riscv: allow different stages with alternatives
> > > > riscv: implement module alternatives
> > > > riscv: implement ALTERNATIVE_2 macro
> > > > riscv: extend concatenated alternatives-lines to the same length
> > > > riscv: prevent compressed instructions in alternatives
> > > > riscv: move boot alternatives to a slightly earlier position
> > > > riscv: Fix accessing pfn bits in PTEs for non-32bit variants
> > > > riscv: add cpufeature handling via alternatives
> > > > riscv: remove FIXMAP_PAGE_IO and fall back to its default value
> > > > riscv: add memory-type errata for T-Head
> > > >
> > > > Wei Fu (2):
> > > > dt-bindings: riscv: add MMU Standard Extensions support for Svpbmt
> > > > riscv: add RISC-V Svpbmt extension support
> > > >
> > > > .../devicetree/bindings/riscv/cpus.yaml | 10 ++
> > > > arch/riscv/Kconfig.erratas | 29 ++--
> > > > arch/riscv/Kconfig.socs | 1 -
> > > > arch/riscv/Makefile | 2 +-
> > > > arch/riscv/errata/Makefile | 2 +-
> > > > arch/riscv/errata/sifive/errata.c | 10 +-
> > > > arch/riscv/errata/thead/Makefile | 1 +
> > > > arch/riscv/errata/thead/errata.c | 85 +++++++++++
> > > > arch/riscv/include/asm/alternative-macros.h | 114 ++++++++-------
> > > > arch/riscv/include/asm/alternative.h | 16 ++-
> > > > arch/riscv/include/asm/errata_list.h | 52 +++++++
> > > > arch/riscv/include/asm/fixmap.h | 2 -
> > > > arch/riscv/include/asm/pgtable-32.h | 17 +++
> > > > arch/riscv/include/asm/pgtable-64.h | 79 +++++++++-
> > > > arch/riscv/include/asm/pgtable-bits.h | 10 --
> > > > arch/riscv/include/asm/pgtable.h | 53 +++++--
> > > > arch/riscv/include/asm/vendorid_list.h | 1 +
> > > > arch/riscv/kernel/Makefile | 1 +
> > > > arch/riscv/{errata => kernel}/alternative.c | 48 ++++++-
> > > > arch/riscv/kernel/cpufeature.c | 136 +++++++++++++++++-
> > > > arch/riscv/kernel/head.S | 2 +
> > > > arch/riscv/kernel/module.c | 29 ++++
> > > > arch/riscv/kernel/sbi.c | 10 +-
> > > > arch/riscv/kernel/smpboot.c | 4 -
> > > > arch/riscv/kernel/traps.c | 2 +-
> > > > arch/riscv/mm/init.c | 1 +
> > > > 26 files changed, 606 insertions(+), 111 deletions(-)
> > > > create mode 100644 arch/riscv/errata/thead/Makefile
> > > > create mode 100644 arch/riscv/errata/thead/errata.c
> > > > rename arch/riscv/{errata => kernel}/alternative.c (59%)
> > > >
> > > > --
> > > > 2.30.2
> > > >
> > > >
> > > > _______________________________________________
> > > > linux-riscv mailing list
> > > > linux-riscv@xxxxxxxxxxxxxxxxxxx
> > > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> > >
> > >
> > >
> > > --
> > > Regards,
> > > Atish
> >
> >
> >
> >
>
>
>
>
--
Regards,
Atish