For kexec -p, the boot cpu can be not the cpu0, this causes the problem
to alloc paca[]. In theory, there is no requirement to assign cpu's logical
id as its present seq by device tree. But we have something like
cpu_first_thread_sibling(), which makes assumption on the mapping inside
a core. Hence partially changing the mapping, i.e. unbind the mapping of
core while keep the mapping inside a core. After this patch, boot-cpu
will always be mapped into the range [0,threads_per_core).
Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
---
arch/powerpc/include/asm/smp.h | 2 ++
arch/powerpc/kernel/prom.c | 27 ++++++++++++++++-----------
arch/powerpc/kernel/setup-common.c | 28 +++++++++++++++++++++++++---
3 files changed, 43 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index fac963e..920a927 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -30,6 +30,8 @@
#include <asm/percpu.h>
extern int boot_cpuid;
+extern int boot_cpuhwid;
+extern int boot_dn_nthreads;
extern int spinning_secondaries;
extern void cpu_die(void);
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index da67606..aca15c1 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -315,8 +315,7 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
const __be32 *intserv;
int i, nthreads;
int len;
- int found = -1;
- int found_thread = 0;
+ bool found = false;
/* We are scanning "cpu" nodes only */
if (type == NULL || strcmp(type, "cpu") != 0)
@@ -341,8 +340,12 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
if (fdt_version(initial_boot_params) >= 2) {
if (be32_to_cpu(intserv[i]) ==
fdt_boot_cpuid_phys(initial_boot_params)) {
- found = boot_cpu_count;
- found_thread = i;
+ /* always map the boot-cpu logical id into the
+ * the range of [0, thread_per_core)
+ */
+ boot_cpuid = i;
+ boot_dn_nthreads = nthreads;
+ found = true;
}
} else {
/*
@@ -351,8 +354,11 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
* off secondary threads.
*/
if (of_get_flat_dt_prop(node,
- "linux,boot-cpu", NULL) != NULL)
- found = boot_cpu_count;
+ "linux,boot-cpu", NULL) != NULL) {
+ boot_cpuid = i;
+ boot_dn_nthreads = nthreads;
+ found = true;
+ }
}
#ifdef CONFIG_SMP
/* logical cpu id is always 0 on UP kernels */
@@ -361,13 +367,12 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
}
/* Not the boot CPU */
- if (found < 0)
+ if (!found)
return 0;
- DBG("boot cpu: logical %d physical %d\n", found,
- be32_to_cpu(intserv[found_thread]));
- boot_cpuid = found;
- set_hard_smp_processor_id(found, be32_to_cpu(intserv[found_thread]));
+ boot_cpuhwid = be32_to_cpu(intserv[boot_cpuid]);
+ DBG("boot cpu: logical %d physical %d\n", boot_cpuid, boot_cpuhwid);
+ set_hard_smp_processor_id(boot_cpuid, boot_cpuhwid);
/*
* PAPR defines "logical" PVR values for cpus that
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 66f7cc6..a683ed1 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -86,7 +86,11 @@ struct machdep_calls *machine_id;
EXPORT_SYMBOL(machine_id);
int boot_cpuid = -1;
+int boot_cpuhwid = -1;
+int boot_dn_nthreads = -1;
EXPORT_SYMBOL_GPL(boot_cpuid);
+EXPORT_SYMBOL_GPL(boot_cpuhwid);
+EXPORT_SYMBOL_GPL(boot_dn_nthreads);
/*
* These are used in binfmt_elf.c to put aux entries on the stack
@@ -461,6 +465,9 @@ void __init smp_setup_cpu_maps(void)
struct device_node *dn;
int cpu = 0;
int nthreads = 1;
+ int online_num = 0;
+ int next_cpu = boot_dn_nthreads;
+ bool btdn_handled = false;
DBG("smp_setup_cpu_maps()\n");
@@ -488,7 +495,21 @@ void __init smp_setup_cpu_maps(void)
nthreads = len / sizeof(int);
- for (j = 0; j < nthreads && cpu < nr_cpu_ids; j++) {
+ if (boot_cpuid < nthreads &&
+ be32_to_cpu(intserv[boot_cpuid]) == boot_cpuhwid) {
+ cpu = 0;
+ btdn_handled = true;
+ } else if ( !btdn_handled &&
+ nr_cpu_ids - online_num <= boot_dn_nthreads)
+ /* online threads in boot dn before using up quota */
+ continue;
+ else {
+ cpu = next_cpu;
+ next_cpu += nthreads;
+ }
+
+
+ for (j = 0; j < nthreads && online_num < nr_cpu_ids; j++) {
bool avail;
DBG(" thread %d -> cpu %d (hard id %d)\n",
@@ -503,12 +524,13 @@ void __init smp_setup_cpu_maps(void)
set_hard_smp_processor_id(cpu, be32_to_cpu(intserv[j]));
set_cpu_possible(cpu, true);
cpu++;
+ online_num++;
}
-
- if (cpu >= nr_cpu_ids) {
+ if (online_num >= nr_cpu_ids) {
of_node_put(dn);
break;
}
+
}
/* If no SMT supported, nthreads is forced to 1 */
--
2.7.4
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