RE: [PATCH 2/3] remoteproc: Add inline coredump functionality

Loic PALLARDY
2020-04-17T07:52:50Z

Hi Rishabh,

> -----Original Message-----
> From: linux-remoteproc-owner@vger.kernel.org <linux-remoteproc-
> owner@vger.kernel.org> On Behalf Of Rishabh Bhatnagar
> Sent: jeudi 16 avril 2020 20:39
> To: linux-remoteproc@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: bjorn.andersson@linaro.org; ohad@wizery.com;
> mathieu.poirier@linaro.org; tsoni@codeaurora.org;
> psodagud@codeaurora.org; sidgup@codeaurora.org; Rishabh Bhatnagar
> <rishabhb@codeaurora.org>
> Subject: [PATCH 2/3] remoteproc: Add inline coredump functionality
>
> This patch adds the inline coredump functionality. The current
> coredump implementation uses vmalloc area to copy all the segments.
> But this might put a lot of strain on low memory targets as the
> firmware size sometimes is in ten's of MBs. The situation becomes
> worse if there are multiple remote processors undergoing recovery
> at the same time. This patch directly copies the device memory to
> userspace buffer and avoids extra memory usage. This requires
> recovery to be halted until data is read by userspace and free
> function is called.
>
> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
> ---
> drivers/remoteproc/remoteproc_coredump.c | 130
> +++++++++++++++++++++++++++++++
> drivers/remoteproc/remoteproc_internal.h | 23 +++++-
> include/linux/remoteproc.h | 2 +
> 3 files changed, 153 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/remoteproc/remoteproc_coredump.c
> b/drivers/remoteproc/remoteproc_coredump.c
> index 9de0467..888b7dec91 100644
> --- a/drivers/remoteproc/remoteproc_coredump.c
> +++ b/drivers/remoteproc/remoteproc_coredump.c
> @@ -12,6 +12,84 @@
> #include <linux/remoteproc.h>
> #include "remoteproc_internal.h"
>
> +static void rproc_free_dump(void *data)
> +{
> + struct rproc_coredump_state *dump_state = data;
> +
> + complete(&dump_state->dump_done);
> +}
> +
> +static unsigned long resolve_addr(loff_t user_offset,
> + struct list_head *segments,
> + unsigned long *data_left)
> +{
> + struct rproc_dump_segment *segment;
> +
> + list_for_each_entry(segment, segments, node) {
> + if (user_offset >= segment->size)
> + user_offset -= segment->size;
> + else
> + break;
> + }
> +
> + if (&segment->node == segments) {
> + *data_left = 0;
> + return 0;
> + }
> +
> + *data_left = segment->size - user_offset;
> +
> + return segment->da + user_offset;
> +}
> +
> +static ssize_t rproc_read_dump(char *buffer, loff_t offset, size_t count,
> + void *data, size_t header_size)
> +{
> + void *device_mem;
> + size_t data_left, copy_size, bytes_left = count;
> + unsigned long addr;
> + struct rproc_coredump_state *dump_state = data;
> + struct rproc *rproc = dump_state->rproc;
> + void *elfcore = dump_state->header;
> +
> + /* Copy the header first */
> + if (offset < header_size) {
> + copy_size = header_size - offset;
> + copy_size = min(copy_size, bytes_left);
> +
> + memcpy(buffer, elfcore + offset, copy_size);
> + offset += copy_size;
> + bytes_left -= copy_size;
> + buffer += copy_size;
> + }
> +
> + while (bytes_left) {
> + addr = resolve_addr(offset - header_size,
> + &rproc->dump_segments, &data_left);
> + /* EOF check */
> + if (data_left == 0) {
> + pr_info("Ramdump complete %lld bytes read",
> offset);
> + break;
> + }
> +
> + copy_size = min_t(size_t, bytes_left, data_left);
> +
> + device_mem = rproc->ops->da_to_va(rproc, addr,
> copy_size);
> + if (!device_mem) {
> + pr_err("Address:%lx with size %zd out of remoteproc
> carveout\n",
> + addr, copy_size);
> + return -ENOMEM;
> + }
> + memcpy(buffer, device_mem, copy_size);
> +
> + offset += copy_size;
> + buffer += copy_size;
> + bytes_left -= copy_size;
> + }
> +
> + return count - bytes_left;
> +}
> +
> static void create_elf_header(void *data, int phnum, struct rproc *rproc)
> {
> struct elf32_phdr *phdr;
> @@ -55,6 +133,58 @@ static void create_elf_header(void *data, int phnum,
> struct rproc *rproc)
> }
>
> /**
> + * rproc_inline_coredump() - perform synchronized coredump
> + * @rproc: rproc handle
> + *
> + * This function will generate an ELF header for the registered segments
> + * and create a devcoredump device associated with rproc. This function
> + * directly copies the segments from device memory to userspace. The
> + * recovery is stalled until the enitire coredump is read. This approach
Typo entire -> entire
> + * avoids using extra vmalloc memory(which can be really large).
> + */
> +void rproc_inline_coredump(struct rproc *rproc)
> +{
> + struct rproc_dump_segment *segment;
> + struct elf32_phdr *phdr;
> + struct elf32_hdr *ehdr;
> + struct rproc_coredump_state *dump_state;
> + size_t header_size;
> + void *data;
> + int phnum = 0;
> +
> + if (list_empty(&rproc->dump_segments))
> + return;
> +
> + header_size = sizeof(*ehdr);
> + list_for_each_entry(segment, &rproc->dump_segments, node) {
> + header_size += sizeof(*phdr);
> +
> + phnum++;
> + }
> +
> + data = vmalloc(header_size);
> + if (!data)
> + return;
> +
> + ehdr = data;
> + create_elf_header(data, phnum, rproc);
> +
> + dump_state = kzalloc(sizeof(*dump_state), GFP_KERNEL);
> + dump_state->rproc = rproc;
> + dump_state->header = data;
> + init_completion(&dump_state->dump_done);
> +
> + dev_coredumpm(&rproc->dev, NULL, dump_state, header_size,
> GFP_KERNEL,
> + rproc_read_dump, rproc_free_dump);
> +
> + /* Wait until the dump is read and free is called */
> + wait_for_completion(&dump_state->dump_done);

Maybe good to add a timeout with value programmable via debugfs?

Regards,
Loic
> +
> + kfree(dump_state);
> +}
> +EXPORT_SYMBOL(rproc_inline_coredump);
> +
> +/**
> * rproc_default_coredump() - perform coredump
> * @rproc: rproc handle
> *
> diff --git a/drivers/remoteproc/remoteproc_internal.h
> b/drivers/remoteproc/remoteproc_internal.h
> index 28b6af2..ea6146e 100644
> --- a/drivers/remoteproc/remoteproc_internal.h
> +++ b/drivers/remoteproc/remoteproc_internal.h
> @@ -24,6 +24,18 @@ struct rproc_debug_trace {
> struct rproc_mem_entry trace_mem;
> };
>
> +struct rproc_coredump_state {
> + struct rproc *rproc;
> + void *header;
> + struct completion dump_done;
> +};
> +
> +enum rproc_coredump_conf {
> + COREDUMP_DEFAULT,
> + COREDUMP_INLINE,
> + COREDUMP_DISABLED,
> +};
> +
> /* from remoteproc_core.c */
> void rproc_release(struct kref *kref);
> irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int vq_id);
> @@ -49,6 +61,7 @@ struct dentry *rproc_create_trace_file(const char
> *name, struct rproc *rproc,
>
> /* from remoteproc_coredump.c */
> void rproc_default_coredump(struct rproc *rproc);
> +void rproc_inline_coredump(struct rproc *rproc);
>
> void rproc_free_vring(struct rproc_vring *rvring);
> int rproc_alloc_vring(struct rproc_vdev *rvdev, int i);
> @@ -125,8 +138,14 @@ struct resource_table
> *rproc_find_loaded_rsc_table(struct rproc *rproc,
> static inline
> void rproc_coredump(struct rproc *rproc)
> {
> - return rproc_default_coredump(rproc);
> -
> + switch (rproc->coredump_conf) {
> + case COREDUMP_DEFAULT:
> + return rproc_default_coredump(rproc);
> + case COREDUMP_INLINE:
> + return rproc_inline_coredump(rproc);
> + default:
> + break;
> + }
> }
>
> #endif /* REMOTEPROC_INTERNAL_H */
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index 16ad666..23298ce 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -459,6 +459,7 @@ struct rproc_dump_segment {
> * @dev: virtual device for refcounting and common remoteproc behavior
> * @power: refcount of users who need this rproc powered up
> * @state: state of the device
> + * @coredump_conf: Currenlty selected coredump configuration
> * @lock: lock which protects concurrent manipulations of the rproc
> * @dbg_dir: debugfs directory of this rproc device
> * @traces: list of trace buffers
> @@ -492,6 +493,7 @@ struct rproc {
> struct device dev;
> atomic_t power;
> unsigned int state;
> + unsigned int coredump_conf;
> struct mutex lock;
> struct dentry *dbg_dir;
> struct list_head traces;
> --
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> Forum,
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