Without the update, we'll only see the new dmesg buffer after the reboot, but previously we could see it right away. Making an oops visible in pstore filesystem before reboot is a somewhat dubious feature, but removing it wasn't an intentional change, so let's restore it.

For this we have to make persistent_ram_save_old() safe for calling multiple times, and also extern it.

Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org Acked-by: Kees Cook keescook@chromium.org --- fs/pstore/ram.c | 2 ++ fs/pstore/ram_core.c | 15 ++++++++------- include/linux/pstore_ram.h | 1 + 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c index 9123cce..16ff733 100644 --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -106,6 +106,8 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, time->tv_sec = 0; time->tv_nsec = 0;

+ /* Update old/shadowed buffer. */ + persistent_ram_save_old(prz); size = persistent_ram_old_size(prz); *buf = kmalloc(size, GFP_KERNEL); if (*buf == NULL) diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index 31f8d18..235513c 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -250,23 +250,24 @@ static void notrace persistent_ram_update(struct persistent_ram_zone *prz, persistent_ram_update_ecc(prz, start, count); }

-static void __init -persistent_ram_save_old(struct persistent_ram_zone *prz) +void persistent_ram_save_old(struct persistent_ram_zone *prz) { struct persistent_ram_buffer *buffer = prz->buffer; size_t size = buffer_size(prz); size_t start = buffer_start(prz); - char *dest;

- persistent_ram_ecc_old(prz); + if (!size) + return;

- dest = kmalloc(size, GFP_KERNEL); - if (dest == NULL) { + if (!prz->old_log) { + persistent_ram_ecc_old(prz); + prz->old_log = kmalloc(size, GFP_KERNEL); + } + if (!prz->old_log) { pr_err("persistent_ram: failed to allocate buffer\n"); return; }

- prz->old_log = dest; prz->old_log_size = size; memcpy(prz->old_log, &buffer->data[start], size - start); memcpy(prz->old_log + size - start, &buffer->data[0], start); diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h index 7ed7fd4..4491e8f 100644 --- a/include/linux/pstore_ram.h +++ b/include/linux/pstore_ram.h @@ -75,6 +75,7 @@ struct persistent_ram_zone *persistent_ram_init_ringbuffer(struct device *dev, int persistent_ram_write(struct persistent_ram_zone *prz, const void *s, unsigned int count);

+void persistent_ram_save_old(struct persistent_ram_zone *prz); size_t persistent_ram_old_size(struct persistent_ram_zone *prz); void *persistent_ram_old(struct persistent_ram_zone *prz); void persistent_ram_free_old(struct persistent_ram_zone *prz);

A handy function that we will use outside of ram_core soon. But so far just factor it out and start using it in post_init().

Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org Acked-by: Kees Cook keescook@chromium.org --- fs/pstore/ram_core.c | 11 ++++++++--- include/linux/pstore_ram.h | 1 + 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index f6650d1..c5fbdbb 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -320,6 +320,13 @@ void persistent_ram_free_old(struct persistent_ram_zone *prz) prz->old_log_size = 0; }

+void persistent_ram_zap(struct persistent_ram_zone *prz) +{ + atomic_set(&prz->buffer->start, 0); + atomic_set(&prz->buffer->size, 0); + persistent_ram_update_header_ecc(prz); +} + static void *persistent_ram_vmap(phys_addr_t start, size_t size) { struct page **pages; @@ -414,8 +421,7 @@ static int __init persistent_ram_post_init(struct persistent_ram_zone *prz, bool }

prz->buffer->sig = PERSISTENT_RAM_SIG; - atomic_set(&prz->buffer->start, 0); - atomic_set(&prz->buffer->size, 0); + persistent_ram_zap(prz);

return 0; } @@ -450,7 +456,6 @@ struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start, goto err;

persistent_ram_post_init(prz, ecc); - persistent_ram_update_header_ecc(prz);

return prz; err: diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h index 4491e8f..3b823d4 100644 --- a/include/linux/pstore_ram.h +++ b/include/linux/pstore_ram.h @@ -69,6 +69,7 @@ struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start, size_t size, bool ecc); void persistent_ram_free(struct persistent_ram_zone *prz); +void persistent_ram_zap(struct persistent_ram_zone *prz); struct persistent_ram_zone *persistent_ram_init_ringbuffer(struct device *dev, bool ecc);

There's no reason to extern it. The patch fixes the annoying sparse warning:

CHECK fs/pstore/inode.c fs/pstore/inode.c:264:5: warning: symbol 'pstore_fill_super' was not declared. Should it be static?

Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org Acked-by: Kees Cook keescook@chromium.org --- fs/pstore/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c index 1950788..49b40ea 100644 --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -258,7 +258,7 @@ fail: return rc; }

-int pstore_fill_super(struct super_block *sb, void *data, int silent) +static int pstore_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode;