Re: [PATCH v2] RISC-V: Add mvendorid, marchid, and mimpid to /proc/cpuinfo output

[Palmer Dabbelt <palmer@dabbelt.com>]

On Mon, 03 Oct 2022 21:35:25 PDT (-0700), Palmer Dabbelt wrote:
> On Mon, 03 Oct 2022 20:44:54 PDT (-0700), anup@brainfault.org wrote:
>> On Tue, Oct 4, 2022 at 8:24 AM Palmer Dabbelt <palmer@dabbelt.com> wrote:
>>>
>>> On Tue, 26 Jul 2022 21:38:29 PDT (-0700), apatel@ventanamicro.com wrote:
>>> > Identifying the underlying RISC-V implementation can be important
>>> > for some of the user space applications. For example, the perf tool
>>> > uses arch specific CPU implementation id (i.e. CPUID) to select a
>>> > JSON file describing custom perf events on a CPU.
>>> >
>>> > Currently, there is no way to identify RISC-V implementation so we
>>> > add mvendorid, marchid, and mimpid to /proc/cpuinfo output.
>>> >
>>> > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
>>> > Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
>>> > Tested-by: Nikita Shubin <n.shubin@yadro.com>
>>> > ---
>>> > Changes since v1:
>>> >  - Use IS_ENABLED() to check CONFIG defines
>>> >  - Added RB and TB tags in commit description
>>> > ---
>>> >  arch/riscv/kernel/cpu.c | 51 +++++++++++++++++++++++++++++++++++++++++
>>> >  1 file changed, 51 insertions(+)
>>>
>>> Sorry for being slow on this one.  I'd been worried about sticking more
>>> stuff into /proc/cpuinfo, as having the only user interface for these
>>> involve parsing /proc/cpuinfo is really just a recipe for disaster.  I
>>> didn't get around do doing something better, though, and waiting for
>>> another release seems kind of silly.
>>
>> In addition to being useful for perf tool, printing vendor and
>> implementation details in /proc/cpuinfo is a very useful info.
>>
>> Users can easily know the underlying CPU implementer using
>> "cat /proc/cpuinfo".
>>
>>>
>>> I was going to go put this on for-next, but it looks like it's causing
>>> kasan boot failures.  I'm not actually quite sure how this is triggering
>>> these, at least based on the backtrace, but there's a bunch of them and
>>> boot hangs.
>>>
>>> Here's the first of them:
>>>
>>> [    3.830416] Hardware name: riscv-virtio,qemu (DT)
>>> [    3.830828] epc : kasan_check_range+0x116/0x14c
>>> [    3.832377]  ra : memset+0x1e/0x4c
>>> [    3.832699] epc : ffffffff8026468e ra : ffffffff80264d6e sp : ff600000832afa60
>>> [    3.833051]  gp : ffffffff81d800a0 tp : ff600000831d2400 t0 : ff60000083224360
>>> [    3.833397]  t1 : ffebfffefffef000 t2 : 0000000000000000 s0 : ff600000832afa90
>>> [    3.833811]  s1 : 0000000000000004 a0 : 0000000000000010 a1 : 0000000000000004
>>> [    3.834210]  a2 : 0000000000000001 a3 : ffffffff801fa22c a4 : ff5ffffffff78000
>>> [    3.834558]  a5 : ffebfffefffef000 a6 : ffebfffefffef001 a7 : ff5ffffffff78003
>>> [    3.834931]  s2 : ff5ffffffff78000 s3 : 0000000000000000 s4 : ffffffff815b59b0
>>> [    3.835292]  s5 : ffffffff81d815e0 s6 : 0000000000000000 s7 : 0000000000000008
>>> [    3.836400]  s8 : ffffffff81d8b0e0 s9 : 0000000000000000 s10: 0000000000000008
>>> [    3.836817]  s11: ff5ffffffff78000 t3 : 0000000000000000 t4 : ffebfffefffef000
>>> [    3.837154]  t5 : ffebfffefffef001 t6 : 0000000000000002
>>> [    3.837471] status: 0000000000000120 badaddr: ffebfffefffef000 cause: 000000000000000d
>>> [    3.837933] [<ffffffff801fa22c>] pcpu_alloc+0x494/0x838
>>> [    3.838324] [<ffffffff801fa5fc>] __alloc_percpu+0x14/0x1c
>>> [    3.838623] [<ffffffff800930fa>] __percpu_init_rwsem+0x1a/0x98
>>> [    3.838995] [<ffffffff80286c5a>] alloc_super+0x148/0x3da
>>> [    3.839631] [<ffffffff80287af2>] sget_fc+0x90/0x2c4
>>> [    3.840240] [<ffffffff80288498>] get_tree_nodev+0x24/0xa4
>>> [    3.840598] [<ffffffff801e919a>] shmem_get_tree+0x14/0x1c
>>> [    3.840891] [<ffffffff80286436>] vfs_get_tree+0x3a/0x11a
>>> [    3.841172] [<ffffffff802ba746>] path_mount+0x2ea/0xb44
>>> [    3.841468] [<ffffffff802bb69a>] sys_mount+0x1b2/0x270
>>> [    3.841790] [<ffffffff80003d1c>] ret_from_syscall+0x0/0x2
>>> [    3.842480] ---[ end trace 0000000000000000 ]---
>>
>> Sure, I will try to fix this ASAP.
>>
>> Are you willing to take this if the above issue is fixed ?
>
> I still think the other interface is better, but it's taking too long
> and some stuff is blocked on getting these to userspace so I'm fine with
> it.

Replying to my own email here as I'm a bit mixed up right now from 
trying to convert over and I can't find Anup's response saying he can't 
reproduce the issues:

It looks like this was just bad luck, for some reason it happens these 
random failures started triggering for me right when I was merging the 
patch (I even went back and they went away).  So I think these were just 
spurious failures.  
https://lore.kernel.org/all/20221009083050.3814850-1-panqinglin2020@iscas.ac.cn/ 
is out as a proposed fix, I've got it in my testing repo as it's making 
the crashes stop -- it smells a bit fishy, though, so I want to get some 
more time to look before merging it.

This one, though, is on for-next.

Thanks!

>
>>
>> Regards,
>> Anup
>>
>>>
>>> >
>>> > diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
>>> > index fba9e9f46a8c..04bcc91c91ea 100644
>>> > --- a/arch/riscv/kernel/cpu.c
>>> > +++ b/arch/riscv/kernel/cpu.c
>>> > @@ -3,10 +3,13 @@
>>> >   * Copyright (C) 2012 Regents of the University of California
>>> >   */
>>> >
>>> > +#include <linux/cpu.h>
>>> >  #include <linux/init.h>
>>> >  #include <linux/seq_file.h>
>>> >  #include <linux/of.h>
>>> > +#include <asm/csr.h>
>>> >  #include <asm/hwcap.h>
>>> > +#include <asm/sbi.h>
>>> >  #include <asm/smp.h>
>>> >  #include <asm/pgtable.h>
>>> >
>>> > @@ -64,6 +67,50 @@ int riscv_of_parent_hartid(struct device_node *node)
>>> >  }
>>> >
>>> >  #ifdef CONFIG_PROC_FS
>>> > +
>>> > +struct riscv_cpuinfo {
>>> > +     unsigned long mvendorid;
>>> > +     unsigned long marchid;
>>> > +     unsigned long mimpid;
>>> > +};
>>> > +static DEFINE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);
>>> > +
>>> > +static int riscv_cpuinfo_starting(unsigned int cpu)
>>> > +{
>>> > +     struct riscv_cpuinfo *ci = this_cpu_ptr(&riscv_cpuinfo);
>>> > +
>>> > +#if IS_ENABLED(CONFIG_RISCV_SBI)
>>> > +     ci->mvendorid = sbi_spec_is_0_1() ? 0 : sbi_get_mvendorid();
>>> > +     ci->marchid = sbi_spec_is_0_1() ? 0 : sbi_get_marchid();
>>> > +     ci->mimpid = sbi_spec_is_0_1() ? 0 : sbi_get_mimpid();
>>> > +#elif IS_ENABLED(CONFIG_RISCV_M_MODE)
>>> > +     ci->mvendorid = csr_read(CSR_MVENDORID);
>>> > +     ci->marchid = csr_read(CSR_MARCHID);
>>> > +     ci->mimpid = csr_read(CSR_MIMPID);
>>> > +#else
>>> > +     ci->mvendorid = 0;
>>> > +     ci->marchid = 0;
>>> > +     ci->mimpid = 0;
>>> > +#endif
>>> > +
>>> > +     return 0;
>>> > +}
>>> > +
>>> > +static int __init riscv_cpuinfo_init(void)
>>> > +{
>>> > +     int ret;
>>> > +
>>> > +     ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "riscv/cpuinfo:starting",
>>> > +                             riscv_cpuinfo_starting, NULL);
>>> > +     if (ret < 0) {
>>> > +             pr_err("cpuinfo: failed to register hotplug callbacks.\n");
>>> > +             return ret;
>>> > +     }
>>> > +
>>> > +     return 0;
>>> > +}
>>> > +device_initcall(riscv_cpuinfo_init);
>>> > +
>>> >  #define __RISCV_ISA_EXT_DATA(UPROP, EXTID) \
>>> >       {                                                       \
>>> >               .uprop = #UPROP,                                \
>>> > @@ -178,6 +225,7 @@ static int c_show(struct seq_file *m, void *v)
>>> >  {
>>> >       unsigned long cpu_id = (unsigned long)v - 1;
>>> >       struct device_node *node = of_get_cpu_node(cpu_id, NULL);
>>> > +     struct riscv_cpuinfo *ci = per_cpu_ptr(&riscv_cpuinfo, cpu_id);
>>> >       const char *compat, *isa;
>>> >
>>> >       seq_printf(m, "processor\t: %lu\n", cpu_id);
>>> > @@ -188,6 +236,9 @@ static int c_show(struct seq_file *m, void *v)
>>> >       if (!of_property_read_string(node, "compatible", &compat)
>>> >           && strcmp(compat, "riscv"))
>>> >               seq_printf(m, "uarch\t\t: %s\n", compat);
>>> > +     seq_printf(m, "mvendorid\t: 0x%lx\n", ci->mvendorid);
>>> > +     seq_printf(m, "marchid\t\t: 0x%lx\n", ci->marchid);
>>> > +     seq_printf(m, "mimpid\t\t: 0x%lx\n", ci->mimpid);
>>> >       seq_puts(m, "\n");
>>> >       of_node_put(node);

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