From 6a89173a25450b679e4a713793b2ed36b077fe56 Mon Sep 17 00:00:00 2001

From: Hari Bathini <hbathini@linux.ibm.com>

Date: Mon, 4 Jul 2022 10:55:42 +0530

Subject: [PATCH 04/28] ppc64: dynamically allocate h/w interrupt stack

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@linux.ibm.com>

Signed-off-by: Lianbo Jiang <lijiang@redhat.com>

---

 defs.h  |  2 +-

 ppc64.c | 51 +++++++++++++++++++++------------------------------

 2 files changed, 22 insertions(+), 31 deletions(-)

diff --git a/defs.h b/defs.h

index c524a05d8105..d8fbeb89e335 100644

--- a/defs.h

+++ b/defs.h

@@ -6311,7 +6311,7 @@ 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 0e1d8678eef5..272eb207074a 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))

@@ -846,23 +844,15 @@ 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]);

-	}

+	} else

+		fprintf(fp, "          hwintrstack: (unused)");

 	fprintf(fp, "\n");

 	fprintf(fp, "           hwstackbuf: %lx\n", (ulong)machdep->machspec->hwstackbuf);

 	fprintf(fp, "          hwstacksize: %d\n", machdep->machspec->hwstacksize);

@@ -1683,9 +1673,10 @@ 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 +1949,7 @@ 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 +2546,7 @@ 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] -

-- 

2.37.1