8:46 a.m.
The following kernel commits (in linux-next now, to be updated)
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:
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(a)nec.com>
---
x86_64.c | 44 +++++++++++++++++++++++++++++++++-----------
1 file changed, 33 insertions(+), 11 deletions(-)
diff --git a/x86_64.c b/x86_64.c
index 74bd1bbde41c..7a5d6f050c89 100644
--- a/x86_64.c
+++ b/x86_64.c
@@ -1290,12 +1290,15 @@ 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");
@@ -1324,7 +1327,7 @@ 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"))
@@ -1337,10 +1340,21 @@ 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;
@@ -1349,8 +1363,8 @@ 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;
@@ -1373,13 +1387,13 @@ 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;
@@ -5625,11 +5639,19 @@ 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"))
@@ -5638,7 +5660,7 @@ 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;
--
2.31.1