crash/0048-x86_64-Fix-for-move-of-per-cpu-variables-into-struct.patch

From 1f6b58b323f669293b4ef8d497fe7867d1411143 Mon Sep 17 00:00:00 2001
From: Kazuhito Hagio <k-hagio-ab@nec.com>
Date: Wed, 7 Dec 2022 09:46:56 +0900
Subject: [PATCH 48/89] x86_64: Fix for move of per-cpu variables into struct
 pcpu_hot

The following kernel commits, which are contained in Linux 6.2-rc1 and
later kernels, introduced struct pcpu_hot and moved several per-cpu
variables into it.

  d7b6d709a76a x86/percpu: Move irq_stack variables next to current_task
  7443b296e699 x86/percpu: Move cpu_number next to current_task
  e57ef2ed97c1 x86: Put hot per CPU variables into a struct

Without the patch, crash fails to start session with the following
error:

  $ crash vmlinux vmcore
  ...
  bt: invalid size request: 0  type: "stack contents"
  bt: read of stack at 0 failed
     <segmentation violation in gdb>

Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
---
 x86_64.c | 44 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 11 deletions(-)

diff --git a/x86_64.c b/x86_64.c
index 292c240e887e..1113a1055f77 100644
--- a/x86_64.c
+++ b/x86_64.c
@@ -1287,12 +1287,15 @@ x86_64_per_cpu_init(void)
 {
 	int i, cpus, cpunumber;
 	struct machine_specific *ms;
-	struct syment *irq_sp, *curr_sp, *cpu_sp, *hardirq_stack_ptr_sp;
+	struct syment *irq_sp, *curr_sp, *cpu_sp, *hardirq_stack_ptr_sp, *pcpu_sp;
 	ulong hardirq_stack_ptr;
 	ulong __per_cpu_load = 0;
+	long hardirq_addr = 0, cpu_addr = 0, curr_addr = 0;
 
 	ms = machdep->machspec;
 
+	pcpu_sp = per_cpu_symbol_search("pcpu_hot");
+
 	hardirq_stack_ptr_sp = per_cpu_symbol_search("hardirq_stack_ptr");
 	irq_sp = per_cpu_symbol_search("per_cpu__irq_stack_union");
 	cpu_sp = per_cpu_symbol_search("per_cpu__cpu_number");
@@ -1321,7 +1324,7 @@ x86_64_per_cpu_init(void)
 		return;
 	}
 
-	if (!cpu_sp || (!irq_sp && !hardirq_stack_ptr_sp))
+	if (!pcpu_sp && (!cpu_sp || (!irq_sp && !hardirq_stack_ptr_sp)))
 		return;
 
 	if (MEMBER_EXISTS("irq_stack_union", "irq_stack"))
@@ -1334,10 +1337,21 @@ x86_64_per_cpu_init(void)
 	if (kernel_symbol_exists("__per_cpu_load"))
 		__per_cpu_load = symbol_value("__per_cpu_load");
 
+	if (pcpu_sp) {
+		hardirq_addr = pcpu_sp->value + MEMBER_OFFSET("pcpu_hot", "hardirq_stack_ptr");
+		cpu_addr = pcpu_sp->value + MEMBER_OFFSET("pcpu_hot", "cpu_number");
+		curr_addr = pcpu_sp->value + MEMBER_OFFSET("pcpu_hot", "current_task");
+	} else {
+		if (hardirq_stack_ptr_sp)
+			hardirq_addr = hardirq_stack_ptr_sp->value;
+		cpu_addr = cpu_sp->value;
+		curr_addr = curr_sp->value;
+	}
+
 	for (i = cpus = 0; i < NR_CPUS; i++) {
 		if (__per_cpu_load && kt->__per_cpu_offset[i] == __per_cpu_load)
 			break;
-		if (!readmem(cpu_sp->value + kt->__per_cpu_offset[i],
+		if (!readmem(cpu_addr + kt->__per_cpu_offset[i],
 		    KVADDR, &cpunumber, sizeof(int),
 		    "cpu number (per_cpu)", QUIET|RETURN_ON_ERROR))
 			break;
@@ -1346,8 +1360,8 @@ x86_64_per_cpu_init(void)
 			break;
 		cpus++;
 
-		if (hardirq_stack_ptr_sp) {
-			if (!readmem(hardirq_stack_ptr_sp->value + kt->__per_cpu_offset[i],
+		if (pcpu_sp || hardirq_stack_ptr_sp) {
+			if (!readmem(hardirq_addr + kt->__per_cpu_offset[i],
 		    	    KVADDR, &hardirq_stack_ptr, sizeof(void *),
 		    	    "hardirq_stack_ptr (per_cpu)", QUIET|RETURN_ON_ERROR))
 				continue;
@@ -1370,13 +1384,13 @@ x86_64_per_cpu_init(void)
 	else
 		kt->cpus = cpus;
 
-	if (DUMPFILE() && curr_sp) {
+	if (DUMPFILE() && (pcpu_sp || curr_sp)) {
 		if ((ms->current = calloc(kt->cpus, sizeof(ulong))) == NULL)
 			error(FATAL, 
 			    "cannot calloc %d x86_64 current pointers!\n",
 				kt->cpus);
 		for (i = 0; i < kt->cpus; i++)
-			if (!readmem(curr_sp->value + kt->__per_cpu_offset[i], 
+			if (!readmem(curr_addr + kt->__per_cpu_offset[i],
 			    KVADDR, &ms->current[i], sizeof(ulong),
 			    "current_task (per_cpu)", RETURN_ON_ERROR))
 				continue;
@@ -5622,11 +5636,19 @@ x86_64_get_smp_cpus(void)
 	char *cpu_pda_buf;
 	ulong level4_pgt, cpu_pda_addr;
 	struct syment *sp;
-	ulong __per_cpu_load = 0;
+	ulong __per_cpu_load = 0, cpu_addr;
 
 	if (!VALID_STRUCT(x8664_pda)) {
-		if (!(sp = per_cpu_symbol_search("per_cpu__cpu_number")) ||
-		    !(kt->flags & PER_CPU_OFF))
+
+		if (!(kt->flags & PER_CPU_OFF))
+			return 1;
+
+		if ((sp = per_cpu_symbol_search("pcpu_hot")) &&
+		    (cpu_addr = MEMBER_OFFSET("pcpu_hot", "cpu_number")) != INVALID_OFFSET)
+			cpu_addr += sp->value;
+		else if ((sp = per_cpu_symbol_search("per_cpu__cpu_number")))
+			cpu_addr = sp->value;
+		else
 			return 1;
 
 		if (kernel_symbol_exists("__per_cpu_load"))
@@ -5635,7 +5657,7 @@ x86_64_get_smp_cpus(void)
 		for (i = cpus = 0; i < NR_CPUS; i++) {
 			if (__per_cpu_load && kt->__per_cpu_offset[i] == __per_cpu_load)
 				break;
-			if (!readmem(sp->value + kt->__per_cpu_offset[i], 
+			if (!readmem(cpu_addr + kt->__per_cpu_offset[i],
 			    KVADDR, &cpunumber, sizeof(int),
 			    "cpu number (per_cpu)", QUIET|RETURN_ON_ERROR))
 				break;
-- 
2.37.1