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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id s44sm11461456pjc.28.2020.05.11.17.32.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 May 2020 17:32:02 -0700 (PDT) Date: Mon, 11 May 2020 17:30:28 -0700 From: Bjorn Andersson To: rishabhb@codeaurora.org Cc: linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, ohad@wizery.com, mathieu.poirier@linaro.org, tsoni@codeaurora.org, psodagud@codeaurora.org, sidgup@codeaurora.org, linux-remoteproc-owner@vger.kernel.org Subject: Re: [PATCH 2/3] remoteproc: Add inline coredump functionality Message-ID: <20200512003028.GA2165@builder.lan> References: <1587062312-4939-1-git-send-email-rishabhb@codeaurora.org> <1587062312-4939-2-git-send-email-rishabhb@codeaurora.org> <20200507202121.GK2329931@builder.lan> <7deb97ab40dd36d5a51111147cf4c14e@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7deb97ab40dd36d5a51111147cf4c14e@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 11 May 17:11 PDT 2020, rishabhb@codeaurora.org wrote: > On 2020-05-07 13:21, Bjorn Andersson wrote: > > On Thu 16 Apr 11:38 PDT 2020, Rishabh Bhatnagar wrote: > > > > > 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 > > > --- > > > 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 > > > #include "remoteproc_internal.h" > > > > > > +static void rproc_free_dump(void *data) > > > > rproc_coredump_free() > > > > > +{ > > > + struct rproc_coredump_state *dump_state = data; > > > + > > > + complete(&dump_state->dump_done); > > > > vfree(dump_state->header); > > > > > +} > > > + > > > +static unsigned long resolve_addr(loff_t user_offset, > > > > rproc_coredump_find_segment() > > > > > + 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 (user_offset < segment->size) { > > *data_left = segment->size - user_offset; > > return segment->da + user_offset; > > } > > > > user_offset -= segment->size; > > > + } > > > > *data_left = 0; > > return 0; > > > > > + > > > + 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; > > > + } > > > > Perhaps you can take inspiration from devcd_readv() here? > > > > > + > > > + while (bytes_left) { > > > + addr = resolve_addr(offset - header_size, > > > + &rproc->dump_segments, &data_left); > > > + /* EOF check */ > > > + if (data_left == 0) { > > > > Afaict data_left denotes the amount of data left in this particular > > segment, rather than in the entire core. > > > Yes, but it only returns 0 when the final segment has been copied > completely. Otherwise it gives data left to copy for every segment > and moves to next segment once the current one is copied. You're right. > > I think you should start by making bytes_left the minimum of the core > > size and @count and then have this loop as long as bytes_left, copying > > data to the buffer either from header or an appropriate segment based on > > the current offset. > > > That would require an extra function that calculates entire core size, > as its not available right now. Do you see any missed corner cases with this > approach? You're looping over all the segments as you're building the header anyways, so you could simply store this in the dump_state. I think this depend more on the ability to reuse the read function between inline and default coredump. Regards, Bjorn > > > + pr_info("Ramdump complete %lld bytes read", offset); > > > > dev_dbg(&rproc->dev, ...) > > > > > + break; > > > + } > > > + > > > + copy_size = min_t(size_t, bytes_left, data_left); > > > + > > > + device_mem = rproc->ops->da_to_va(rproc, addr, copy_size); > > > > rproc_da_to_va() > > > > > + if (!device_mem) { > > > + pr_err("Address:%lx with size %zd out of remoteproc carveout\n", > > > > dev_err(&rproc->dev, "coredump: %#lx size %#zx outside of carveouts\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 > > > + * 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; > > > > This can live on the stack, unless you follow my suggestion below... > > > > > + 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; > > > > ehdr is unused. > > > > > + 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); > > > > I can help feeling that if you vmalloc() either the header or the entire > > thing depending on DEFAULT vs INLINE and populate it with either all > > segments or just the header, then you should be able to use the same > > (custom) read function to serve both cases. > > > > You should by doing this be able to avoid some duplication, your two > > code paths would not diverge and the main difference would be if you > > wait or not below (the kfree would have to go in the rproc_free_dump). > > > > > + > > > + /* Wait until the dump is read and free is called */ > > > + wait_for_completion(&dump_state->dump_done); > > > + > > > + 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 { > > > > This is only used within remoteproc_coredump.c, so please move it there. > > > > > + struct rproc *rproc; > > > + void *header; > > > + struct completion dump_done; > > > +}; > > > + > > > +enum rproc_coredump_conf { > > > > How about rproc_coredump_mechanism? > > > > > + 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; > > > + } > > > > I think this better belong inside remoteproc_coredump.c > > > > Regards, > > Bjorn > > > > > } > > > > > > #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; > > > -- > > > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora > > > Forum, > > > a Linux Foundation Collaborative Project