[Crash-utility] [External Mail][????] Re: ramdump support for va_bits_actual

[赵乾利]

Hi
I made almost the same patch to fix the problem with arm64 in version 5.4...

One very small change can merged together,vmemmap_start has a little error:
[arch/arm64/include/asm/memory.h]
 56 #define VMEMMAP_START           (-VMEMMAP_SIZE - SZ_2M)
in crash arm64.c
-               vmemmap_start = (-vmemmap_size);
+               vmemmap_start = (-vmemmap_size - MEGABYTES(2));


BTW,in arm64_VTOP,it's easier to use the physvirt_offset directly
@@ -1148,8 +1155,7 @@ arm64_VTOP(ulong addr)
                }

                if (addr >= machdep->machspec->page_offset)
-                       return machdep->machspec->phys_offset
-                               + (addr - machdep->machspec->page_offset);
+                       return (addr + machdep->machspec->physvirt_offset);

________________________________________
From: crash-utility-bounces at redhat.com <crash-utility-bounces at redhat.com> on behalf of Dave Anderson <anderson at redhat.com>
Sent: Saturday, April 18, 2020 0:32
To: Discussion list for crash utility usage,    maintenance and development
Subject: [External Mail][????] Re: [Crash-utility] ramdump support for va_bits_actual

----- Original Message -----
> Hi Dave,
>
> Noticed that raw ramdumps of 5.4 kernel aren't working with crash tip.
> With the patches attached, I could get it working. Please take a look.
>
> Thanks,
> Vinayak
>

Hi Vinayak,

A couple quick questions come to mind...

First, I haven't checked all possible READMEM plugins, but for example, if this
function is run on a live system, the -1 file descriptor would cause the READMEM()
call to fail:

 static void
+arm64_calc_physvirt_offset(void)
+{
+       struct machine_specific *ms = machdep->machspec;
+       ulong physvirt_offset;
+       struct syment *sp;
+
+       ms->physvirt_offset = ms->phys_offset - ms->page_offset;
+
+       if ((sp = kernel_symbol_search("physvirt_offset")) &&
+                       machdep->machspec->kimage_voffset) {
+               if (READMEM(-1, &physvirt_offset, sizeof(physvirt_offset),
+                       sp->value, sp->value -
+                       machdep->machspec->kimage_voffset) > 0) {
+                               ms->physvirt_offset = physvirt_offset;
+               }
+       }
+
+       if (CRASHDEBUG(1))
+               fprintf(fp, "using %lx as physvirt_offset\n", ms->physvirt_offset);
+}

And here -- are you missing some brackets?  (run "make warn")

But regardless of that, why are you setting it back to 48 if it's greater than 48?

diff --git a/arm64.c b/arm64.c
index 31d6e90..04efc13 100644
--- a/arm64.c
+++ b/arm64.c
@@ -4011,6 +4011,7 @@ arm64_calc_virtual_memory_ranges(void)
        struct machine_specific *ms = machdep->machspec;
        ulong value, vmemmap_start, vmemmap_end, vmemmap_size, vmalloc_end;
        char *string;
+       int ret;
        ulong PUD_SIZE = UNINITIALIZED;

        if (!machdep->machspec->CONFIG_ARM64_VA_BITS) {
@@ -4018,6 +4019,12 @@ arm64_calc_virtual_memory_ranges(void)
                        value = atol(string);
                        free(string);
                        machdep->machspec->CONFIG_ARM64_VA_BITS = value;
+               } else if (kt->ikconfig_flags & IKCONFIG_AVAIL) {
+                       if ((ret = get_kernel_config("CONFIG_ARM64_VA_BITS",
+                                       &string)) == IKCONFIG_STR)
+                               machdep->machspec->CONFIG_ARM64_VA_BITS = atol(string);
+                               if (machdep->machspec->CONFIG_ARM64_VA_BITS > 48)
+                                       machdep->machspec->CONFIG_ARM64_VA_BITS = 48;
                }
        }

Thanks,
  Dave

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