* [PATCH v4] powerpc/kexec_file: use current CPU info while setting up FDT
@ 2021-04-19 8:36 Sourabh Jain
2021-04-19 11:53 ` Hari Bathini
0 siblings, 1 reply; 4+ messages in thread
From: Sourabh Jain @ 2021-04-19 8:36 UTC (permalink / raw)
To: mpe; +Cc: mahesh, Sourabh Jain, linuxppc-dev, stable, hbathini, bauerman
kexec_file_load uses initial_boot_params in setting up the device-tree
for the kernel to be loaded. Though initial_boot_params holds info
about CPUs at the time of boot, it doesn't account for hot added CPUs.
So, kexec'ing with kexec_file_load syscall would leave the kexec'ed
kernel with inaccurate CPU info. Also, if kdump kernel is loaded with
kexec_file_load syscall and the system crashes on a hot added CPU,
capture kernel hangs failing to identify the boot CPU.
Kernel panic - not syncing: sysrq triggered crash
CPU: 24 PID: 6065 Comm: echo Kdump: loaded Not tainted 5.12.0-rc5upstream #54
Call Trace:
[c0000000e590fac0] [c0000000007b2400] dump_stack+0xc4/0x114 (unreliable)
[c0000000e590fb00] [c000000000145290] panic+0x16c/0x41c
[c0000000e590fba0] [c0000000008892e0] sysrq_handle_crash+0x30/0x40
[c0000000e590fc00] [c000000000889cdc] __handle_sysrq+0xcc/0x1f0
[c0000000e590fca0] [c00000000088a538] write_sysrq_trigger+0xd8/0x178
[c0000000e590fce0] [c0000000005e9b7c] proc_reg_write+0x10c/0x1b0
[c0000000e590fd10] [c0000000004f26d0] vfs_write+0xf0/0x330
[c0000000e590fd60] [c0000000004f2aec] ksys_write+0x7c/0x140
[c0000000e590fdb0] [c000000000031ee0] system_call_exception+0x150/0x290
[c0000000e590fe10] [c00000000000ca5c] system_call_common+0xec/0x278
--- interrupt: c00 at 0x7fff905b9664
NIP: 00007fff905b9664 LR: 00007fff905320c4 CTR: 0000000000000000
REGS: c0000000e590fe80 TRAP: 0c00 Not tainted (5.12.0-rc5upstream)
MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 28000242
XER: 00000000
IRQMASK: 0
GPR00: 0000000000000004 00007ffff5fedf30 00007fff906a7300 0000000000000001
GPR04: 000001002a7355b0 0000000000000002 0000000000000001 00007ffff5fef616
GPR08: 0000000000000001 0000000000000000 0000000000000000 0000000000000000
GPR12: 0000000000000000 00007fff9073a160 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 00007fff906a4ee0 0000000000000002 0000000000000001
GPR24: 00007fff906a0898 0000000000000000 0000000000000002 000001002a7355b0
GPR28: 0000000000000002 00007fff906a1790 000001002a7355b0 0000000000000002
NIP [00007fff905b9664] 0x7fff905b9664
LR [00007fff905320c4] 0x7fff905320c4
--- interrupt: c00
To avoid this from happening, extract current CPU info from of_root
device node and use it for setting up the fdt in kexec_file_load case.
Fixes: 6ecd0163d360 ("powerpc/kexec_file: Add appropriate regions for memory reserve map")
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Cc: <stable@vger.kernel.org>
---
arch/powerpc/kexec/file_load_64.c | 98 +++++++++++++++++++++++++++++++
1 file changed, 98 insertions(+)
---
Changelog:
v1 -> v3
- https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-April/227756.html
v3 -> v4
- Rearranged if-else statement in update_cpus_node function to avoid
redundant checks for positive cpus_offset.
---
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index 02b9e4d0dc40..195ef303d530 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -960,6 +960,99 @@ unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image)
return fdt_size;
}
+/**
+ * add_node_prop - Read property from device node structure and add
+ * them to fdt.
+ * @fdt: Flattened device tree of the kernel
+ * @node_offset: offset of the node to add a property at
+ * np: device node pointer
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+static int add_node_prop(void *fdt, int node_offset, const struct device_node *np)
+{
+ int ret = 0;
+ struct property *pp;
+ unsigned long flags;
+
+ if (!np)
+ return -EINVAL;
+
+ raw_spin_lock_irqsave(&devtree_lock, flags);
+ for (pp = np->properties; pp; pp = pp->next) {
+ ret = fdt_setprop(fdt, node_offset, pp->name,
+ pp->value, pp->length);
+ if (ret < 0) {
+ pr_err("Unable to add %s property: %s\n",
+ pp->name, fdt_strerror(ret));
+ goto out;
+ }
+ }
+out:
+ raw_spin_unlock_irqrestore(&devtree_lock, flags);
+ return ret;
+}
+
+/**
+ * update_cpus_node - Update cpus node of flattened device-tree using of_root
+ * device node.
+ * @fdt: Flattened device tree of the kernel.
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+static int update_cpus_node(void *fdt)
+{
+ struct device_node *cpus_node, *dn;
+ int cpus_offset, cpus_subnode_off, ret = 0;
+
+ cpus_offset = fdt_path_offset(fdt, "/cpus");
+ if (cpus_offset < 0 && cpus_offset != -FDT_ERR_NOTFOUND) {
+ pr_err("Malformed device tree: error reading /cpus node: %s\n",
+ fdt_strerror(cpus_offset));
+ return cpus_offset;
+ } else {
+ if (cpus_offset > 0) {
+ ret = fdt_del_node(fdt, cpus_offset);
+ if (ret < 0) {
+ pr_err("Error deleting /cpus node: %s\n",
+ fdt_strerror(ret));
+ return -EINVAL;
+ }
+ }
+
+ /* Add cpus node to fdt */
+ cpus_offset = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
+ "cpus");
+ if (cpus_offset < 0) {
+ pr_err("Error creating /cpus node: %s\n",
+ fdt_strerror(cpus_offset));
+ return -EINVAL;
+ }
+
+ /* Add cpus node properties */
+ cpus_node = of_find_node_by_path("/cpus");
+ ret = add_node_prop(fdt, cpus_offset, cpus_node);
+ if (ret < 0)
+ return ret;
+
+ /* Loop through all subnodes of cpus and add them to fdt */
+ for_each_node_by_type(dn, "cpu") {
+ cpus_subnode_off = fdt_add_subnode(fdt,
+ cpus_offset,
+ dn->full_name);
+ if (cpus_subnode_off < 0) {
+ pr_err("Unable to add %s subnode: %s\n",
+ dn->full_name, fdt_strerror(cpus_subnode_off));
+ return cpus_subnode_off;
+ }
+ ret = add_node_prop(fdt, cpus_subnode_off, dn);
+ if (ret < 0)
+ return ret;
+ }
+ }
+ return ret;
+}
+
/**
* setup_new_fdt_ppc64 - Update the flattend device-tree of the kernel
* being loaded.
@@ -1020,6 +1113,11 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
}
}
+ /* Update cpus nodes information to account hotplug CPUs. */
+ ret = update_cpus_node(fdt);
+ if (ret < 0)
+ return ret;
+
/* Update memory reserve map */
ret = get_reserved_memory_ranges(&rmem);
if (ret)
--
2.26.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v4] powerpc/kexec_file: use current CPU info while setting up FDT
2021-04-19 8:36 [PATCH v4] powerpc/kexec_file: use current CPU info while setting up FDT Sourabh Jain
@ 2021-04-19 11:53 ` Hari Bathini
2021-04-19 12:21 ` Michael Ellerman
0 siblings, 1 reply; 4+ messages in thread
From: Hari Bathini @ 2021-04-19 11:53 UTC (permalink / raw)
To: Sourabh Jain, mpe; +Cc: mahesh, stable, bauerman, linuxppc-dev
On 19/04/21 2:06 pm, Sourabh Jain wrote:
> kexec_file_load uses initial_boot_params in setting up the device-tree
> for the kernel to be loaded. Though initial_boot_params holds info
> about CPUs at the time of boot, it doesn't account for hot added CPUs.
>
> So, kexec'ing with kexec_file_load syscall would leave the kexec'ed
> kernel with inaccurate CPU info. Also, if kdump kernel is loaded with
> kexec_file_load syscall and the system crashes on a hot added CPU,
> capture kernel hangs failing to identify the boot CPU.
>
> Kernel panic - not syncing: sysrq triggered crash
> CPU: 24 PID: 6065 Comm: echo Kdump: loaded Not tainted 5.12.0-rc5upstream #54
> Call Trace:
> [c0000000e590fac0] [c0000000007b2400] dump_stack+0xc4/0x114 (unreliable)
> [c0000000e590fb00] [c000000000145290] panic+0x16c/0x41c
> [c0000000e590fba0] [c0000000008892e0] sysrq_handle_crash+0x30/0x40
> [c0000000e590fc00] [c000000000889cdc] __handle_sysrq+0xcc/0x1f0
> [c0000000e590fca0] [c00000000088a538] write_sysrq_trigger+0xd8/0x178
> [c0000000e590fce0] [c0000000005e9b7c] proc_reg_write+0x10c/0x1b0
> [c0000000e590fd10] [c0000000004f26d0] vfs_write+0xf0/0x330
> [c0000000e590fd60] [c0000000004f2aec] ksys_write+0x7c/0x140
> [c0000000e590fdb0] [c000000000031ee0] system_call_exception+0x150/0x290
> [c0000000e590fe10] [c00000000000ca5c] system_call_common+0xec/0x278
> --- interrupt: c00 at 0x7fff905b9664
> NIP: 00007fff905b9664 LR: 00007fff905320c4 CTR: 0000000000000000
> REGS: c0000000e590fe80 TRAP: 0c00 Not tainted (5.12.0-rc5upstream)
> MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 28000242
> XER: 00000000
> IRQMASK: 0
> GPR00: 0000000000000004 00007ffff5fedf30 00007fff906a7300 0000000000000001
> GPR04: 000001002a7355b0 0000000000000002 0000000000000001 00007ffff5fef616
> GPR08: 0000000000000001 0000000000000000 0000000000000000 0000000000000000
> GPR12: 0000000000000000 00007fff9073a160 0000000000000000 0000000000000000
> GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> GPR20: 0000000000000000 00007fff906a4ee0 0000000000000002 0000000000000001
> GPR24: 00007fff906a0898 0000000000000000 0000000000000002 000001002a7355b0
> GPR28: 0000000000000002 00007fff906a1790 000001002a7355b0 0000000000000002
> NIP [00007fff905b9664] 0x7fff905b9664
> LR [00007fff905320c4] 0x7fff905320c4
> --- interrupt: c00
>
> To avoid this from happening, extract current CPU info from of_root
> device node and use it for setting up the fdt in kexec_file_load case.
>
> Fixes: 6ecd0163d360 ("powerpc/kexec_file: Add appropriate regions for memory reserve map")
>
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
> Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
> Cc: <stable@vger.kernel.org>
> ---
> arch/powerpc/kexec/file_load_64.c | 98 +++++++++++++++++++++++++++++++
> 1 file changed, 98 insertions(+)
>
> ---
> Changelog:
>
> v1 -> v3
> - https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-April/227756.html
>
> v3 -> v4
> - Rearranged if-else statement in update_cpus_node function to avoid
> redundant checks for positive cpus_offset.
> ---
>
> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
> index 02b9e4d0dc40..195ef303d530 100644
> --- a/arch/powerpc/kexec/file_load_64.c
> +++ b/arch/powerpc/kexec/file_load_64.c
> @@ -960,6 +960,99 @@ unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image)
> return fdt_size;
> }
>
> +/**
> + * add_node_prop - Read property from device node structure and add
> + * them to fdt.
> + * @fdt: Flattened device tree of the kernel
> + * @node_offset: offset of the node to add a property at
> + * np: device node pointer
> + *
> + * Returns 0 on success, negative errno on error.
> + */
> +static int add_node_prop(void *fdt, int node_offset, const struct device_node *np)
> +{
> + int ret = 0;
> + struct property *pp;
> + unsigned long flags;
> +
> + if (!np)
> + return -EINVAL;
> +
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> + for (pp = np->properties; pp; pp = pp->next) {
> + ret = fdt_setprop(fdt, node_offset, pp->name,
> + pp->value, pp->length);
> + if (ret < 0) {
> + pr_err("Unable to add %s property: %s\n",
> + pp->name, fdt_strerror(ret));
> + goto out;
> + }
> + }
> +out:
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> + return ret;
> +}
> +
> +/**
> + * update_cpus_node - Update cpus node of flattened device-tree using of_root
> + * device node.
> + * @fdt: Flattened device tree of the kernel.
> + *
> + * Returns 0 on success, negative errno on error.
> + */
> +static int update_cpus_node(void *fdt)
> +{
> + struct device_node *cpus_node, *dn;
> + int cpus_offset, cpus_subnode_off, ret = 0;
> +
> + cpus_offset = fdt_path_offset(fdt, "/cpus");
> + if (cpus_offset < 0 && cpus_offset != -FDT_ERR_NOTFOUND) {
> + pr_err("Malformed device tree: error reading /cpus node: %s\n",
> + fdt_strerror(cpus_offset));
> + return cpus_offset;
> + } else {
> + if (cpus_offset > 0) {
> + ret = fdt_del_node(fdt, cpus_offset);
> + if (ret < 0) {
> + pr_err("Error deleting /cpus node: %s\n",
> + fdt_strerror(ret));
> + return -EINVAL;
> + }
> + }
> +
> + /* Add cpus node to fdt */
> + cpus_offset = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
> + "cpus");
> + if (cpus_offset < 0) {
> + pr_err("Error creating /cpus node: %s\n",
> + fdt_strerror(cpus_offset));
> + return -EINVAL;
> + }
> +
> + /* Add cpus node properties */
> + cpus_node = of_find_node_by_path("/cpus");
> + ret = add_node_prop(fdt, cpus_offset, cpus_node);
> + if (ret < 0)
> + return ret;
> +
> + /* Loop through all subnodes of cpus and add them to fdt */
> + for_each_node_by_type(dn, "cpu") {
> + cpus_subnode_off = fdt_add_subnode(fdt,
> + cpus_offset,
> + dn->full_name);
> + if (cpus_subnode_off < 0) {
> + pr_err("Unable to add %s subnode: %s\n",
> + dn->full_name, fdt_strerror(cpus_subnode_off));
> + return cpus_subnode_off;
> + }
> + ret = add_node_prop(fdt, cpus_subnode_off, dn);
> + if (ret < 0)
> + return ret;
> + }
The above code block doesn't really need an explicit else condition..
> + }
> + return ret;
> +}
Thanks
Hari
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v4] powerpc/kexec_file: use current CPU info while setting up FDT
2021-04-19 11:53 ` Hari Bathini
@ 2021-04-19 12:21 ` Michael Ellerman
2021-04-20 5:50 ` Sourabh Jain
0 siblings, 1 reply; 4+ messages in thread
From: Michael Ellerman @ 2021-04-19 12:21 UTC (permalink / raw)
To: Hari Bathini, Sourabh Jain; +Cc: mahesh, stable, bauerman, linuxppc-dev
Hari Bathini <hbathini@linux.ibm.com> writes:
> On 19/04/21 2:06 pm, Sourabh Jain wrote:
>> kexec_file_load uses initial_boot_params in setting up the device-tree
>> for the kernel to be loaded. Though initial_boot_params holds info
>> about CPUs at the time of boot, it doesn't account for hot added CPUs.
>>
>> So, kexec'ing with kexec_file_load syscall would leave the kexec'ed
>> kernel with inaccurate CPU info. Also, if kdump kernel is loaded with
>> kexec_file_load syscall and the system crashes on a hot added CPU,
>> capture kernel hangs failing to identify the boot CPU.
>>
>> Kernel panic - not syncing: sysrq triggered crash
>> CPU: 24 PID: 6065 Comm: echo Kdump: loaded Not tainted 5.12.0-rc5upstream #54
>> Call Trace:
>> [c0000000e590fac0] [c0000000007b2400] dump_stack+0xc4/0x114 (unreliable)
>> [c0000000e590fb00] [c000000000145290] panic+0x16c/0x41c
>> [c0000000e590fba0] [c0000000008892e0] sysrq_handle_crash+0x30/0x40
>> [c0000000e590fc00] [c000000000889cdc] __handle_sysrq+0xcc/0x1f0
>> [c0000000e590fca0] [c00000000088a538] write_sysrq_trigger+0xd8/0x178
>> [c0000000e590fce0] [c0000000005e9b7c] proc_reg_write+0x10c/0x1b0
>> [c0000000e590fd10] [c0000000004f26d0] vfs_write+0xf0/0x330
>> [c0000000e590fd60] [c0000000004f2aec] ksys_write+0x7c/0x140
>> [c0000000e590fdb0] [c000000000031ee0] system_call_exception+0x150/0x290
>> [c0000000e590fe10] [c00000000000ca5c] system_call_common+0xec/0x278
>> --- interrupt: c00 at 0x7fff905b9664
>> NIP: 00007fff905b9664 LR: 00007fff905320c4 CTR: 0000000000000000
>> REGS: c0000000e590fe80 TRAP: 0c00 Not tainted (5.12.0-rc5upstream)
>> MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 28000242
>> XER: 00000000
>> IRQMASK: 0
>> GPR00: 0000000000000004 00007ffff5fedf30 00007fff906a7300 0000000000000001
>> GPR04: 000001002a7355b0 0000000000000002 0000000000000001 00007ffff5fef616
>> GPR08: 0000000000000001 0000000000000000 0000000000000000 0000000000000000
>> GPR12: 0000000000000000 00007fff9073a160 0000000000000000 0000000000000000
>> GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>> GPR20: 0000000000000000 00007fff906a4ee0 0000000000000002 0000000000000001
>> GPR24: 00007fff906a0898 0000000000000000 0000000000000002 000001002a7355b0
>> GPR28: 0000000000000002 00007fff906a1790 000001002a7355b0 0000000000000002
>> NIP [00007fff905b9664] 0x7fff905b9664
>> LR [00007fff905320c4] 0x7fff905320c4
>> --- interrupt: c00
>>
>> To avoid this from happening, extract current CPU info from of_root
>> device node and use it for setting up the fdt in kexec_file_load case.
>>
>> Fixes: 6ecd0163d360 ("powerpc/kexec_file: Add appropriate regions for memory reserve map")
>>
>> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
>> Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
>> Cc: <stable@vger.kernel.org>
>> ---
>> arch/powerpc/kexec/file_load_64.c | 98 +++++++++++++++++++++++++++++++
>> 1 file changed, 98 insertions(+)
>>
>> ---
>> Changelog:
>>
>> v1 -> v3
>> - https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-April/227756.html
>>
>> v3 -> v4
>> - Rearranged if-else statement in update_cpus_node function to avoid
>> redundant checks for positive cpus_offset.
>> ---
>>
>> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
>> index 02b9e4d0dc40..195ef303d530 100644
>> --- a/arch/powerpc/kexec/file_load_64.c
>> +++ b/arch/powerpc/kexec/file_load_64.c
>> @@ -960,6 +960,99 @@ unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image)
>> return fdt_size;
>> }
>>
>> +/**
>> + * add_node_prop - Read property from device node structure and add
>> + * them to fdt.
>> + * @fdt: Flattened device tree of the kernel
>> + * @node_offset: offset of the node to add a property at
>> + * np: device node pointer
>> + *
>> + * Returns 0 on success, negative errno on error.
>> + */
>> +static int add_node_prop(void *fdt, int node_offset, const struct device_node *np)
>> +{
>> + int ret = 0;
>> + struct property *pp;
>> + unsigned long flags;
>> +
>> + if (!np)
>> + return -EINVAL;
>> +
>> + raw_spin_lock_irqsave(&devtree_lock, flags);
>> + for (pp = np->properties; pp; pp = pp->next) {
>> + ret = fdt_setprop(fdt, node_offset, pp->name,
>> + pp->value, pp->length);
>> + if (ret < 0) {
>> + pr_err("Unable to add %s property: %s\n",
>> + pp->name, fdt_strerror(ret));
>> + goto out;
>> + }
>> + }
>> +out:
>> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>> + return ret;
>> +}
>> +
>> +/**
>> + * update_cpus_node - Update cpus node of flattened device-tree using of_root
>> + * device node.
>> + * @fdt: Flattened device tree of the kernel.
>> + *
>> + * Returns 0 on success, negative errno on error.
>> + */
>> +static int update_cpus_node(void *fdt)
>> +{
>> + struct device_node *cpus_node, *dn;
>> + int cpus_offset, cpus_subnode_off, ret = 0;
>> +
>> + cpus_offset = fdt_path_offset(fdt, "/cpus");
>> + if (cpus_offset < 0 && cpus_offset != -FDT_ERR_NOTFOUND) {
>> + pr_err("Malformed device tree: error reading /cpus node: %s\n",
>> + fdt_strerror(cpus_offset));
>> + return cpus_offset;
>> + } else {
>
>
>> + if (cpus_offset > 0) {
>> + ret = fdt_del_node(fdt, cpus_offset);
>> + if (ret < 0) {
>> + pr_err("Error deleting /cpus node: %s\n",
>> + fdt_strerror(ret));
>> + return -EINVAL;
>> + }
>> + }
>> +
>> + /* Add cpus node to fdt */
>> + cpus_offset = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
>> + "cpus");
>> + if (cpus_offset < 0) {
>> + pr_err("Error creating /cpus node: %s\n",
>> + fdt_strerror(cpus_offset));
>> + return -EINVAL;
>> + }
>> +
>> + /* Add cpus node properties */
>> + cpus_node = of_find_node_by_path("/cpus");
>> + ret = add_node_prop(fdt, cpus_offset, cpus_node);
>> + if (ret < 0)
>> + return ret;
>> +
>> + /* Loop through all subnodes of cpus and add them to fdt */
>> + for_each_node_by_type(dn, "cpu") {
>> + cpus_subnode_off = fdt_add_subnode(fdt,
>> + cpus_offset,
>> + dn->full_name);
>> + if (cpus_subnode_off < 0) {
>> + pr_err("Unable to add %s subnode: %s\n",
>> + dn->full_name, fdt_strerror(cpus_subnode_off));
>> + return cpus_subnode_off;
>> + }
>> + ret = add_node_prop(fdt, cpus_subnode_off, dn);
>> + if (ret < 0)
>> + return ret;
>> + }
>
> The above code block doesn't really need an explicit else condition..
Yeah, use the early return to avoid having to indent all the rest of
that logic.
Please send a v5.
cheers
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v4] powerpc/kexec_file: use current CPU info while setting up FDT
2021-04-19 12:21 ` Michael Ellerman
@ 2021-04-20 5:50 ` Sourabh Jain
0 siblings, 0 replies; 4+ messages in thread
From: Sourabh Jain @ 2021-04-20 5:50 UTC (permalink / raw)
To: Michael Ellerman, Hari Bathini; +Cc: mahesh, stable, bauerman, linuxppc-dev
On 19/04/21 5:51 pm, Michael Ellerman wrote:
> Hari Bathini <hbathini@linux.ibm.com> writes:
>> On 19/04/21 2:06 pm, Sourabh Jain wrote:
>>> kexec_file_load uses initial_boot_params in setting up the device-tree
>>> for the kernel to be loaded. Though initial_boot_params holds info
>>> about CPUs at the time of boot, it doesn't account for hot added CPUs.
>>>
>>> So, kexec'ing with kexec_file_load syscall would leave the kexec'ed
>>> kernel with inaccurate CPU info. Also, if kdump kernel is loaded with
>>> kexec_file_load syscall and the system crashes on a hot added CPU,
>>> capture kernel hangs failing to identify the boot CPU.
>>>
>>> Kernel panic - not syncing: sysrq triggered crash
>>> CPU: 24 PID: 6065 Comm: echo Kdump: loaded Not tainted 5.12.0-rc5upstream #54
>>> Call Trace:
>>> [c0000000e590fac0] [c0000000007b2400] dump_stack+0xc4/0x114 (unreliable)
>>> [c0000000e590fb00] [c000000000145290] panic+0x16c/0x41c
>>> [c0000000e590fba0] [c0000000008892e0] sysrq_handle_crash+0x30/0x40
>>> [c0000000e590fc00] [c000000000889cdc] __handle_sysrq+0xcc/0x1f0
>>> [c0000000e590fca0] [c00000000088a538] write_sysrq_trigger+0xd8/0x178
>>> [c0000000e590fce0] [c0000000005e9b7c] proc_reg_write+0x10c/0x1b0
>>> [c0000000e590fd10] [c0000000004f26d0] vfs_write+0xf0/0x330
>>> [c0000000e590fd60] [c0000000004f2aec] ksys_write+0x7c/0x140
>>> [c0000000e590fdb0] [c000000000031ee0] system_call_exception+0x150/0x290
>>> [c0000000e590fe10] [c00000000000ca5c] system_call_common+0xec/0x278
>>> --- interrupt: c00 at 0x7fff905b9664
>>> NIP: 00007fff905b9664 LR: 00007fff905320c4 CTR: 0000000000000000
>>> REGS: c0000000e590fe80 TRAP: 0c00 Not tainted (5.12.0-rc5upstream)
>>> MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 28000242
>>> XER: 00000000
>>> IRQMASK: 0
>>> GPR00: 0000000000000004 00007ffff5fedf30 00007fff906a7300 0000000000000001
>>> GPR04: 000001002a7355b0 0000000000000002 0000000000000001 00007ffff5fef616
>>> GPR08: 0000000000000001 0000000000000000 0000000000000000 0000000000000000
>>> GPR12: 0000000000000000 00007fff9073a160 0000000000000000 0000000000000000
>>> GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>>> GPR20: 0000000000000000 00007fff906a4ee0 0000000000000002 0000000000000001
>>> GPR24: 00007fff906a0898 0000000000000000 0000000000000002 000001002a7355b0
>>> GPR28: 0000000000000002 00007fff906a1790 000001002a7355b0 0000000000000002
>>> NIP [00007fff905b9664] 0x7fff905b9664
>>> LR [00007fff905320c4] 0x7fff905320c4
>>> --- interrupt: c00
>>>
>>> To avoid this from happening, extract current CPU info from of_root
>>> device node and use it for setting up the fdt in kexec_file_load case.
>>>
>>> Fixes: 6ecd0163d360 ("powerpc/kexec_file: Add appropriate regions for memory reserve map")
>>>
>>> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
>>> Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
>>> Cc: <stable@vger.kernel.org>
>>> ---
>>> arch/powerpc/kexec/file_load_64.c | 98 +++++++++++++++++++++++++++++++
>>> 1 file changed, 98 insertions(+)
>>>
>>> ---
>>> Changelog:
>>>
>>> v1 -> v3
>>> - https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-April/227756.html
>>>
>>> v3 -> v4
>>> - Rearranged if-else statement in update_cpus_node function to avoid
>>> redundant checks for positive cpus_offset.
>>> ---
>>>
>>> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
>>> index 02b9e4d0dc40..195ef303d530 100644
>>> --- a/arch/powerpc/kexec/file_load_64.c
>>> +++ b/arch/powerpc/kexec/file_load_64.c
>>> @@ -960,6 +960,99 @@ unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image)
>>> return fdt_size;
>>> }
>>>
>>> +/**
>>> + * add_node_prop - Read property from device node structure and add
>>> + * them to fdt.
>>> + * @fdt: Flattened device tree of the kernel
>>> + * @node_offset: offset of the node to add a property at
>>> + * np: device node pointer
>>> + *
>>> + * Returns 0 on success, negative errno on error.
>>> + */
>>> +static int add_node_prop(void *fdt, int node_offset, const struct device_node *np)
>>> +{
>>> + int ret = 0;
>>> + struct property *pp;
>>> + unsigned long flags;
>>> +
>>> + if (!np)
>>> + return -EINVAL;
>>> +
>>> + raw_spin_lock_irqsave(&devtree_lock, flags);
>>> + for (pp = np->properties; pp; pp = pp->next) {
>>> + ret = fdt_setprop(fdt, node_offset, pp->name,
>>> + pp->value, pp->length);
>>> + if (ret < 0) {
>>> + pr_err("Unable to add %s property: %s\n",
>>> + pp->name, fdt_strerror(ret));
>>> + goto out;
>>> + }
>>> + }
>>> +out:
>>> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>>> + return ret;
>>> +}
>>> +
>>> +/**
>>> + * update_cpus_node - Update cpus node of flattened device-tree using of_root
>>> + * device node.
>>> + * @fdt: Flattened device tree of the kernel.
>>> + *
>>> + * Returns 0 on success, negative errno on error.
>>> + */
>>> +static int update_cpus_node(void *fdt)
>>> +{
>>> + struct device_node *cpus_node, *dn;
>>> + int cpus_offset, cpus_subnode_off, ret = 0;
>>> +
>>> + cpus_offset = fdt_path_offset(fdt, "/cpus");
>>> + if (cpus_offset < 0 && cpus_offset != -FDT_ERR_NOTFOUND) {
>>> + pr_err("Malformed device tree: error reading /cpus node: %s\n",
>>> + fdt_strerror(cpus_offset));
>>> + return cpus_offset;
>>> + } else {
>>
>>> + if (cpus_offset > 0) {
>>> + ret = fdt_del_node(fdt, cpus_offset);
>>> + if (ret < 0) {
>>> + pr_err("Error deleting /cpus node: %s\n",
>>> + fdt_strerror(ret));
>>> + return -EINVAL;
>>> + }
>>> + }
>>> +
>>> + /* Add cpus node to fdt */
>>> + cpus_offset = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
>>> + "cpus");
>>> + if (cpus_offset < 0) {
>>> + pr_err("Error creating /cpus node: %s\n",
>>> + fdt_strerror(cpus_offset));
>>> + return -EINVAL;
>>> + }
>>> +
>>> + /* Add cpus node properties */
>>> + cpus_node = of_find_node_by_path("/cpus");
>>> + ret = add_node_prop(fdt, cpus_offset, cpus_node);
>>> + if (ret < 0)
>>> + return ret;
>>> +
>>> + /* Loop through all subnodes of cpus and add them to fdt */
>>> + for_each_node_by_type(dn, "cpu") {
>>> + cpus_subnode_off = fdt_add_subnode(fdt,
>>> + cpus_offset,
>>> + dn->full_name);
>>> + if (cpus_subnode_off < 0) {
>>> + pr_err("Unable to add %s subnode: %s\n",
>>> + dn->full_name, fdt_strerror(cpus_subnode_off));
>>> + return cpus_subnode_off;
>>> + }
>>> + ret = add_node_prop(fdt, cpus_subnode_off, dn);
>>> + if (ret < 0)
>>> + return ret;
>>> + }
>> The above code block doesn't really need an explicit else condition..
> Yeah, use the early return to avoid having to indent all the rest of
> that logic.
>
> Please send a v5.
>
> Thanks for the review.
>
> v5 sent.
>
> - Sourabh Jain
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2021-04-19 8:36 [PATCH v4] powerpc/kexec_file: use current CPU info while setting up FDT Sourabh Jain
2021-04-19 11:53 ` Hari Bathini
2021-04-19 12:21 ` Michael Ellerman
2021-04-20 5:50 ` Sourabh Jain
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