From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ot1-x361.google.com ([2607:f8b0:4864:20::361]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mKqht-000pCi-ES for kexec@lists.infradead.org; Mon, 30 Aug 2021 23:28:53 +0000 Received: by mail-ot1-x361.google.com with SMTP id c42-20020a05683034aa00b0051f4b99c40cso10283231otu.0 for ; Mon, 30 Aug 2021 16:28:47 -0700 (PDT) Date: Mon, 30 Aug 2021 16:28:44 -0700 From: Ivan Delalande Subject: [PATCH v2] makedumpfile: support --partial-dmesg on 5.10+ kernels Message-ID: References: Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: HAGIO =?utf-8?B?S0FaVUhJVE8o6JCp5bC+44CA5LiA5LuBKQ==?= Cc: "kexec@lists.infradead.org" , John Ogness The new printk ringbuffer implementation added in kernel v5.10 with commit 896fbe20b4e2 ("printk: use the lockless ringbuffer") also exported a new vmcore symbol "clear_seq" to keep track where dmesg had been cleared like "clear_idx" on previous versions. Use it in dump_lockless_dmesg when --partial-dmesg is passed to find and start dumping messages only from that index. On v5.13, commit 7d7a23a91c91 ("printk: use seqcount_latch for clear_seq") converted it from a simple value, and so an additional step is required to find and retrieve the sequence at the right offset in the latched_seq structure it now uses. Signed-off-by: Ivan Delalande --- makedumpfile.c | 12 ++++++++++++ makedumpfile.h | 6 ++++++ printk.c | 19 +++++++++++++++++++ 3 files changed, 37 insertions(+) diff --git a/makedumpfile.c b/makedumpfile.c index b1b3b42..ac17f19 100644 --- a/makedumpfile.c +++ b/makedumpfile.c @@ -1555,6 +1555,7 @@ get_symbol_info(void) SYMBOL_INIT(pgdat_list, "pgdat_list"); SYMBOL_INIT(contig_page_data, "contig_page_data"); SYMBOL_INIT(prb, "prb"); + SYMBOL_INIT(clear_seq, "clear_seq"); SYMBOL_INIT(log_buf, "log_buf"); SYMBOL_INIT(log_buf_len, "log_buf_len"); SYMBOL_INIT(log_end, "log_end"); @@ -2000,6 +2001,9 @@ get_structure_info(void) OFFSET_INIT(printk_info.text_len, "printk_info", "text_len"); OFFSET_INIT(atomic_long_t.counter, "atomic_long_t", "counter"); + + SIZE_INIT(latched_seq, "latched_seq"); + OFFSET_INIT(latched_seq.val, "latched_seq", "val"); } else if (SIZE(printk_log) != NOT_FOUND_STRUCTURE) { /* * In kernel 3.11-rc4 the log structure name was renamed @@ -2231,6 +2235,7 @@ write_vmcoreinfo_data(void) WRITE_SYMBOL("pgdat_list", pgdat_list); WRITE_SYMBOL("contig_page_data", contig_page_data); WRITE_SYMBOL("prb", prb); + WRITE_SYMBOL("clear_seq", clear_seq); WRITE_SYMBOL("log_buf", log_buf); WRITE_SYMBOL("log_buf_len", log_buf_len); WRITE_SYMBOL("log_end", log_end); @@ -2266,6 +2271,7 @@ write_vmcoreinfo_data(void) WRITE_STRUCTURE_SIZE("printk_ringbuffer", printk_ringbuffer); WRITE_STRUCTURE_SIZE("prb_desc", prb_desc); WRITE_STRUCTURE_SIZE("printk_info", printk_info); + WRITE_STRUCTURE_SIZE("latched_seq", latched_seq); } else if (info->flag_use_printk_log) WRITE_STRUCTURE_SIZE("printk_log", printk_log); else @@ -2335,6 +2341,8 @@ write_vmcoreinfo_data(void) WRITE_MEMBER_OFFSET("printk_info.text_len", printk_info.text_len); WRITE_MEMBER_OFFSET("atomic_long_t.counter", atomic_long_t.counter); + + WRITE_MEMBER_OFFSET("latched_seq.val", latched_seq.val); } else if (info->flag_use_printk_log) { WRITE_MEMBER_OFFSET("printk_log.ts_nsec", printk_log.ts_nsec); WRITE_MEMBER_OFFSET("printk_log.len", printk_log.len); @@ -2676,6 +2684,7 @@ read_vmcoreinfo(void) READ_SYMBOL("pgdat_list", pgdat_list); READ_SYMBOL("contig_page_data", contig_page_data); READ_SYMBOL("prb", prb); + READ_SYMBOL("clear_seq", clear_seq); READ_SYMBOL("log_buf", log_buf); READ_SYMBOL("log_buf_len", log_buf_len); READ_SYMBOL("log_end", log_end); @@ -2784,6 +2793,9 @@ read_vmcoreinfo(void) READ_MEMBER_OFFSET("printk_info.text_len", printk_info.text_len); READ_MEMBER_OFFSET("atomic_long_t.counter", atomic_long_t.counter); + + READ_STRUCTURE_SIZE("latched_seq", latched_seq); + READ_MEMBER_OFFSET("latched_seq.val", latched_seq.val); } else if (SIZE(printk_log) != NOT_FOUND_STRUCTURE) { info->flag_use_printk_ringbuffer = FALSE; info->flag_use_printk_log = TRUE; diff --git a/makedumpfile.h b/makedumpfile.h index ca50a89..bd9e2f6 100644 --- a/makedumpfile.h +++ b/makedumpfile.h @@ -1656,6 +1656,7 @@ struct symbol_table { unsigned long long pgdat_list; unsigned long long contig_page_data; unsigned long long prb; + unsigned long long clear_seq; unsigned long long log_buf; unsigned long long log_buf_len; unsigned long long log_end; @@ -1749,6 +1750,7 @@ struct size_table { long printk_ringbuffer; long prb_desc; long printk_info; + long latched_seq; /* * for Xen extraction @@ -1973,6 +1975,10 @@ struct offset_table { long counter; } atomic_long_t; + struct latched_seq_s { + long val; + } latched_seq; + /* * symbols on ppc64 arch */ diff --git a/printk.c b/printk.c index e8501c7..61e0b26 100644 --- a/printk.c +++ b/printk.c @@ -145,6 +145,7 @@ dump_record(struct prb_map *m, unsigned long id) int dump_lockless_dmesg(void) { + unsigned long long clear_seq; unsigned long head_id; unsigned long tail_id; unsigned long kaddr; @@ -216,6 +217,24 @@ dump_lockless_dmesg(void) OFFSET(atomic_long_t.counter)); head_id = ULONG(m.desc_ring + OFFSET(prb_desc_ring.head_id) + OFFSET(atomic_long_t.counter)); + if (info->flag_partial_dmesg && SYMBOL(clear_seq) != NOT_FOUND_SYMBOL) { + if (!readmem(VADDR, SYMBOL(clear_seq), &clear_seq, + sizeof(clear_seq))) { + ERRMSG("Can't get clear_seq.\n"); + goto out_text_data; + } + if (SIZE(latched_seq) != NOT_FOUND_STRUCTURE) { + kaddr = SYMBOL(clear_seq) + OFFSET(latched_seq.val) + + (clear_seq & 0x1) * sizeof(clear_seq); + if (!readmem(VADDR, kaddr, &clear_seq, + sizeof(clear_seq))) { + ERRMSG("Can't get latched clear_seq.\n"); + goto out_text_data; + } + } + tail_id = head_id - head_id % m.desc_ring_count + + clear_seq % m.desc_ring_count; + } if (!open_dump_file()) { ERRMSG("Can't open output file.\n"); -- 2.33.0 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec