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SubjectRe: [PATCH v11 4/4] fw_cfg: write vmcoreinfo details
On Thu, Feb 01, 2018 at 02:03:00PM +0100, Marc-André Lureau wrote:
> @@ -314,6 +359,37 @@ struct fw_cfg_sysfs_entry {
> struct device *dev;
> };
>
> +#ifdef CONFIG_CRASH_CORE
> +static ssize_t write_vmcoreinfo(struct device *dev, const struct fw_cfg_file *f)
> +{
> + struct vmci {
> + __le16 host_format;
> + __le16 guest_format;
> + __le32 size;
> + __le64 paddr;
> + } __packed;
> + static struct vmci *data;
> + ssize_t ret;
> +
> + data = kmalloc(sizeof(struct vmci), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + *data = (struct vmci) {
> + .guest_format = cpu_to_le16(VMCOREINFO_FORMAT_ELF),
> + .size = cpu_to_le32(VMCOREINFO_NOTE_SIZE),
> + .paddr = cpu_to_le64(paddr_vmcoreinfo_note())
> + };
> + /* spare ourself reading host format support for now since we
> + * don't know what else to format - host may ignore ours
> + */
> + ret = fw_cfg_write_blob(dev, f->select, data, 0, sizeof(struct vmci));
> +
> + kfree(data);
> + return ret;
> +}
> +#endif /* CONFIG_CRASH_CORE */
> +
> /* get fw_cfg_sysfs_entry from kobject member */
> static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
> {

kmalloc during crash is I think a bad idea.
How about preallocating on probe?

diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 33e0256..ffd81d1 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -363,22 +363,33 @@ struct fw_cfg_sysfs_entry {
};

#ifdef CONFIG_CRASH_CORE
+
+struct vmci {
+ __le16 host_format;
+ __le16 guest_format;
+ __le32 size;
+ __le64 paddr;
+} *fw_cfg_vmcore_data;
+
+static int fw_cfg_vmcore_init(void)
+{
+ fw_cfg_vmcore_data = kmalloc(sizeof(*fw_cfg_vmcore_data), GFP_KERNEL);
+ if (!fw_cfg_vmcore_data)
+ return -ENOMEM;
+ return 0;
+}
+
+static int fw_cfg_vmcore_cleanup(void)
+{
+ kfree(fw_cfg_vmcore_data);
+}
+
static ssize_t write_vmcoreinfo(struct device *dev, const struct fw_cfg_file *f)
{
- struct vmci {
- __le16 host_format;
- __le16 guest_format;
- __le32 size;
- __le64 paddr;
- } __packed;
static struct vmci *data;
ssize_t ret;

- data = kmalloc(sizeof(struct vmci), GFP_KERNEL);
- if (!data)
- return -ENOMEM;
-
- *data = (struct vmci) {
+ *fw_cfg_vmcore_data = (struct vmci) {
.guest_format = cpu_to_le16(VMCOREINFO_FORMAT_ELF),
.size = cpu_to_le32(VMCOREINFO_NOTE_SIZE),
.paddr = cpu_to_le64(paddr_vmcoreinfo_note())
@@ -386,11 +397,23 @@ static ssize_t write_vmcoreinfo(struct device *dev, const struct fw_cfg_file *f)
/* spare ourself reading host format support for now since we
* don't know what else to format - host may ignore ours
*/
- ret = fw_cfg_write_blob(dev, f->select, data, 0, sizeof(struct vmci));
+ ret = fw_cfg_write_blob(dev, f->select, fw_cfg_vmcore_data, 0,
+ sizeof(*fw_cfg_vmcore_data));

- kfree(data);
return ret;
}
+
+#else
+
+static int fw_cfg_vmcore_init(void)
+{
+ return 0;
+}
+
+static int fw_cfg_vmcore_cleanup(void)
+{
+}
+
#endif /* CONFIG_CRASH_CORE */

/* get fw_cfg_sysfs_entry from kobject member */
@@ -725,11 +748,15 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
if (fw_cfg_sel_ko)
return -EBUSY;

+ err = fw_cfg_vmcore_init();
+ if (err)
+ goto err_sel;
+
/* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
err = -ENOMEM;
fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
if (!fw_cfg_sel_ko)
- goto err_sel;
+ goto err_vmcore;
fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
if (!fw_cfg_fname_kset)
goto err_name;
@@ -764,6 +791,8 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
err_name:
fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
+err_vmcore:
+ fw_cfg_vmcore_cleanup();
err_sel:
return err;
}
@@ -776,6 +805,7 @@ static int fw_cfg_sysfs_remove(struct platform_device *pdev)
fw_cfg_io_cleanup();
fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
+ fw_cfg_vmcore_cleanup();
return 0;
}

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