Re: [Crash-utility] ramdump support for va_bits_actual

Hi Dave, On Sat, Apr 18, 2020 at 2:08 PM Dave Anderson <anderson(a)redhat.com&gt; wrote: > > > > ----- 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: I changed it like this and it works for ramdump. I don't actually have a live setup to try this. Let me try to set up one. diff --git a/arm64.c b/arm64.c index 04efc13..fce3f8e 100644 --- a/arm64.c +++ b/arm64.c @@ -981,7 +981,7 @@ arm64_calc_physvirt_offset(void) if ((sp = kernel_symbol_search("physvirt_offset")) && machdep->machspec->kimage_voffset) { - if (READMEM(-1, &physvirt_offset, sizeof(physvirt_offset), + if (READMEM(pc->mfd, &physvirt_offset, sizeof(physvirt_offset), sp->value, sp->value - machdep->machspec->kimage_voffset) > 0) { ms->physvirt_offset = physvirt_offset; > > 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") > I did try "make warn" and it does not show any issues.Am I missing something?

> But regardless of that, why are you setting it back to 48 if it's greater > than 48? > I did that because machspec->CONFIG_ARM64_VA_BITS is used for calculation of vmemmap size. In kernel vmemmap size is calculated using VA_BITS_MIN and it is defined like this #if VA_BITS > 48 #define VA_BITS_MIN (48) #else #define VA_BITS_MIN (VA_BITS) #endif But I realize now that its not the right thing to do, because machspec->CONFIG_ARM64_VA_BITS is later used in arm64_calc_VA_BITS to verify machspec->VA_BITS. So what about this ? diff --git a/arm64.c b/arm64.c index 04efc13..a35a30e 100644 --- a/arm64.c +++ b/arm64.c @@ -4023,8 +4023,6 @@ arm64_calc_virtual_memory_ranges(void) 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; } } @@ -4049,7 +4047,12 @@ arm64_calc_virtual_memory_ranges(void) #define STRUCT_PAGE_MAX_SHIFT 6 if (ms->VA_BITS_ACTUAL) { - vmemmap_size = (1UL) << (ms->CONFIG_ARM64_VA_BITS - machdep->pageshift - 1 + STRUCT_PAGE_MAX_SHIFT); + ulong va_bits_min = 48; + + if (machdep->machspec->CONFIG_ARM64_VA_BITS < 48) + va_bits_min = ms->CONFIG_ARM64_VA_BITS; + + vmemmap_size = (1UL) << (va_bits_min - machdep->pageshift - 1 + STRUCT_PAGE_MAX_SHIFT); vmalloc_end = (- PUD_SIZE - vmemmap_size - KILOBYTES(64)); vmemmap_start = (-vmemmap_size); ms->vmalloc_end = vmalloc_end - 1;