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@xxxxxxxxxxxxx>
> ---
> 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.
Thanks,
Kazu
> fprintf(fp, " hwstackbuf: %lx\n", (ulong)machdep->machspec->hwstackbuf);
> @@ -1683,9 +1672,10 @@ ppc64_check_sp_in_HWintrstack(ulong sp, struct bt_info *bt)
> *
> * Note: HW Interrupt stack is used only in 2.4 kernel.
> */
> - if (is_task_active(bt->task) && (tt->panic_task != bt->task) &&
> - machdep->machspec->hwintrstack[bt->tc->processor]) {
> + if (machdep->machspec->hwintrstack && is_task_active(bt->task) &&
> + (bt->task != tt->panic_task)) {
> ulong newsp;
> +
> readmem(machdep->machspec->hwintrstack[bt->tc->processor],
> KVADDR, &newsp, sizeof(ulong),
> "stack pointer", FAULT_ON_ERROR);
> @@ -1958,7 +1948,7 @@ ppc64_back_trace(struct gnu_request *req, struct bt_info *bt)
> bt->stackbase = irqstack;
> bt->stacktop = bt->stackbase + STACKSIZE();
> alter_stackbuf(bt);
> - } else if (ms->hwintrstack[bt->tc->processor]) {
> + } else if (ms->hwintrstack) {
> bt->stacktop = ms->hwintrstack[bt->tc->processor] +
> sizeof(ulong);
> bt->stackbase = ms->hwintrstack[bt->tc->processor] -
> @@ -2555,7 +2545,7 @@ retry:
> goto retry;
> }
>
> - if (check_intrstack && ms->hwintrstack[bt->tc->processor]) {
> + if (check_intrstack && ms->hwintrstack) {
> bt->stacktop = ms->hwintrstack[bt->tc->processor] +
> sizeof(ulong);
> bt->stackbase = ms->hwintrstack[bt->tc->processor] -
--
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