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 | 1 +
arch/powerpc/kernel/prom.c | 25 ++++++++++++++-----------
arch/powerpc/kernel/setup-common.c | 21 +++++++++++++++++++++
3 files changed, 36 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index fac963e..1299100 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -30,6 +30,7 @@
#include <asm/percpu.h>
extern int boot_cpuid;
+extern int boot_cpuhwid;
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..d0ebb25 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 +340,11 @@ 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;
+ found = true;
}
} else {
/*
@@ -351,8 +353,10 @@ 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;
+ found = true;
+ }
}
#ifdef CONFIG_SMP
/* logical cpu id is always 0 on UP kernels */
@@ -361,13 +365,12 @@ 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..1a67344 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -86,6 +86,7 @@ struct machdep_calls *machine_id;
EXPORT_SYMBOL(machine_id);
int boot_cpuid = -1;
+int boot_cpuhwid = -1;
EXPORT_SYMBOL_GPL(boot_cpuid);
/*
@@ -459,11 +460,17 @@ static void __init cpu_init_thread_core_maps(int tpc)
void __init smp_setup_cpu_maps(void)
{
struct device_node *dn;
+ struct device_node *boot_dn = NULL;
+ bool handling_bootdn = true;
int cpu = 0;
int nthreads = 1;
DBG("smp_setup_cpu_maps()\n");
+again:
+ /* E.g. kexec will not boot from the 1st core. So firstly loop to find out
+ * the dn of boot-cpu, and map them onto [0, nthreads)
+ */
for_each_node_by_type(dn, "cpu") {
const __be32 *intserv;
__be32 cpu_be;
@@ -488,6 +495,16 @@ void __init smp_setup_cpu_maps(void)
nthreads = len / sizeof(int);
+ if (handling_bootdn) {
+ if (boot_cpuid < nthreads &&
+ be32_to_cpu(intserv[boot_cpuid]) == boot_cpuhwid) {
+ boot_dn = dn;
+ }
+ if (boot_dn == NULL)
+ continue;
+ } else if (dn == boot_dn)
+ continue;
+
for (j = 0; j < nthreads && cpu < nr_cpu_ids; j++) {
bool avail;
@@ -509,6 +526,10 @@ void __init smp_setup_cpu_maps(void)
of_node_put(dn);
break;
}
+ if (handling_bootdn) {
+ handling_bootdn = false;
+ goto again;
+ }
}
/* If no SMT supported, nthreads is forced to 1 */
--
2.7.4
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