From: Peng Wang <wangpeng15@xiaomi.com> stable inclusion from stable-5.10 category: feature commit:7684bd334d9d4ca4f09873e88d9c0131a2cf6c3b issue: #I4919J -------------------------------- When initialing a prz, if invalid data is found (no PERSISTENT_RAM_SIG), the function call path looks like this: ramoops_init_prz -> persistent_ram_new -> persistent_ram_post_init -> persistent_ram_zap persistent_ram_zap As we can see, persistent_ram_zap() is called twice. We can avoid this by adding an option to persistent_ram_new(), and only call persistent_ram_zap() when it is needed. Signed-off-by: Peng Wang <wangpeng15@xiaomi.com> [kees: minor tweak to exit path and commit log] Signed-off-by: Kees Cook <keescook@chromium.org> (cherry picked from commit 7684bd334d9d4ca4f09873e88d9c0131a2cf6c3b) Signed-off-by: roger <kongzhengrong@huawei.com> --- fs/pstore/ram.c | 4 +--- fs/pstore/ram_core.c | 15 +++++++++------ include/linux/pstore_ram.h | 1 + 3 files changed, 11 insertions(+), 9 deletions(-) diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c index b2ecfa34b2ff..b9cae4c54d1b 100644 --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -653,7 +653,7 @@ static int ramoops_init_prz(const char *name, label = kasprintf(GFP_KERNEL, "ramoops:%s", name); *prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info, - cxt->memtype, 0, label); + cxt->memtype, PRZ_FLAG_ZAP_OLD, label); if (IS_ERR(*prz)) { int err = PTR_ERR(*prz); @@ -662,8 +662,6 @@ static int ramoops_init_prz(const char *name, return err; } - persistent_ram_zap(*prz); - *paddr += sz; return 0; diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index 51185f334589..0269fc343ca5 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -490,6 +490,7 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, struct persistent_ram_ecc_info *ecc_info) { int ret; + bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD); ret = persistent_ram_init_ecc(prz, ecc_info); if (ret) @@ -504,23 +505,25 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, } if (buffer_size(prz) > prz->buffer_size || - buffer_start(prz) > buffer_size(prz)) + buffer_start(prz) > buffer_size(prz)) { pr_info("found existing invalid buffer, size %zu, start %zu\n", buffer_size(prz), buffer_start(prz)); - else { + zap = true; + } else { pr_debug("found existing buffer, size %zu, start %zu\n", buffer_size(prz), buffer_start(prz)); persistent_ram_save_old(prz); - return 0; } } else { pr_debug("no valid data in buffer (sig = 0x%08x)\n", prz->buffer->sig); + prz->buffer->sig = sig; + zap = true; } - /* Rewind missing or invalid memory area. */ - prz->buffer->sig = sig; - persistent_ram_zap(prz); + /* Reset missing, invalid, or single-use memory area. */ + if (zap) + persistent_ram_zap(prz); return 0; } diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h index 602d64725222..6e94980357d2 100644 --- a/include/linux/pstore_ram.h +++ b/include/linux/pstore_ram.h @@ -30,6 +30,7 @@ * PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required. */ #define PRZ_FLAG_NO_LOCK BIT(0) +#define PRZ_FLAG_ZAP_OLD BIT(1) struct persistent_ram_buffer; struct rs_control; -- 2.17.1