Re: [Crash-utility] [PATCH 2/6] ppc64: dynamically allocate h/w interrupt stack

Hi Hari thank you for the patches. On 2022/06/29 4:19, Hari Bathini wrote: > Only older kernel (v2.4) used h/w interrupt stack to store frames when > CPU received IPI. Memory used for this in 'struct machine_specific' is > useless for later kernels. For the sake of backward compatibility keep > h/w interrupt stack but dynamically allocate memory for it and save > some bytes from being wasted. > > Signed-off-by: Hari Bathini <hbathini(a)linux.ibm.com&gt; > --- > defs.h | 2 +- > ppc64.c | 48 +++++++++++++++++++----------------------------- > 2 files changed, 20 insertions(+), 30 deletions(-) > > diff --git a/defs.h b/defs.h > index 7d3b734..d1d3ea9 100644 > --- a/defs.h > +++ b/defs.h > @@ -6303,7 +6303,7 @@ struct ppc64_vmemmap { > * Used to store the HW interrupt stack. It is only for 2.4. > */ > struct machine_specific { > - ulong hwintrstack[NR_CPUS]; > + ulong *hwintrstack; > char *hwstackbuf; > uint hwstacksize; > > diff --git a/ppc64.c b/ppc64.c > index 0e1d867..fe96cfa 100644 > --- a/ppc64.c > +++ b/ppc64.c > @@ -256,7 +256,7 @@ static int set_ppc64_max_physmem_bits(void) > } > > struct machine_specific ppc64_machine_specific = { > - .hwintrstack = { 0 }, > + .hwintrstack = NULL, > .hwstackbuf = 0, > .hwstacksize = 0, > .pte_rpn_shift = PTE_RPN_SHIFT_DEFAULT, > @@ -275,7 +275,7 @@ struct machine_specific ppc64_machine_specific = { > }; > > struct machine_specific book3e_machine_specific = { > - .hwintrstack = { 0 }, > + .hwintrstack = NULL, > .hwstackbuf = 0, > .hwstacksize = 0, > .pte_rpn_shift = PTE_RPN_SHIFT_L4_BOOK3E_64K, > @@ -676,6 +676,9 @@ ppc64_init(int when) > */ > offset = MEMBER_OFFSET("paca_struct", "xHrdIntStack"); > paca_sym = symbol_value("paca"); > + if (!(machdep->machspec->hwintrstack = > + (ulong *)calloc(NR_CPUS, sizeof(ulong)))) > + error(FATAL, "cannot malloc hwintrstack space."); > for (cpu = 0; cpu < kt->cpus; cpu++) { > readmem(paca_sym + (paca_size * cpu) + offset, > KVADDR, > @@ -686,14 +689,9 @@ ppc64_init(int when) > machdep->machspec->hwstacksize = 8 * machdep->pagesize; > if ((machdep->machspec->hwstackbuf = (char *) > malloc(machdep->machspec->hwstacksize)) == NULL) > - error(FATAL, "cannot malloc hwirqstack space."); > - } else > - /* > - * 'xHrdIntStack' member in "paca_struct" is not > - * available for 2.6 kernel. > - */ > - BZERO(&machdep->machspec->hwintrstack, > - NR_CPUS*sizeof(ulong)); > + error(FATAL, "cannot malloc hwirqstack buffer space."); > + } > + > if (!machdep->hz) { > machdep->hz = HZ; > if (THIS_KERNEL_VERSION >= LINUX(2,6,0)) > @@ -846,22 +844,13 @@ ppc64_dump_machdep_table(ulong arg) > fprintf(fp, " is_vmaddr: %s\n", > machdep->machspec->is_vmaddr == book3e_is_vmaddr ? > "book3e_is_vmaddr()" : "ppc64_is_vmaddr()"); > - fprintf(fp, " hwintrstack[%d]: ", NR_CPUS); > - for (c = 0; c < NR_CPUS; c++) { > - for (others = 0, i = c; i < NR_CPUS; i++) { > - if (machdep->machspec->hwintrstack[i]) > - others++; > + if (machdep->machspec->hwintrstack) { > + fprintf(fp, " hwintrstack[%d]: ", NR_CPUS); > + for (c = 0; c < NR_CPUS; c++) { > + fprintf(fp, "%s%016lx ", > + ((c % 4) == 0) ? "\n " : "", > + machdep->machspec->hwintrstack[c]); > } > - if (!others) { > - fprintf(fp, "%s%s", > - c && ((c % 4) == 0) ? "\n " : "", > - c ? "(remainder unused)" : "(unused)"); > - break; > - } > - > - fprintf(fp, "%s%016lx ", > - ((c % 4) == 0) ? "\n " : "", > - machdep->machspec->hwintrstack[c]); > } > fprintf(fp, "\n"); I would prefer to print something like "hwintrstack: (unused)" to show clearly when unused, but this (an empty line?) is also fine if you like.