crash/SOURCES/0001-Fix-rd-command-for-zram-data-display-in-Linux-6.2-an.patch

From 38acd02c7fc09843ffb10fc2d695cccdd10cc7f6 Mon Sep 17 00:00:00 2001
From: Chengen Du <chengen.du@canonical.com>
Date: Fri, 17 Nov 2023 11:45:33 +0800
Subject: [PATCH 01/14] Fix "rd" command for zram data display in Linux 6.2 and
 later

Kernel commit 7ac07a26dea7 ("zram: preparation for multi-zcomp support")
replaced "compressor" member with "comp_algs" in the zram struct.
Without the patch, the "rd" command can triggers the following error:

  rd: WARNING: Some pages are swapped out to zram. Please run mod -s zram.
  rd: invalid user virtual address: ffff7d23f010  type: "64-bit UVADDR"

Related kernel commit:
  84b33bf78889 ("zram: introduce recompress sysfs knob")

Signed-off-by: Chengen Du <chengen.du@canonical.com>
Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
---
 defs.h     |  1 +
 diskdump.c | 47 ++++++++++++++++++++++++++++++-----------------
 2 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/defs.h b/defs.h
index 788f63ada739..2cae5b61e589 100644
--- a/defs.h
+++ b/defs.h
@@ -2227,6 +2227,7 @@ struct offset_table {                    /* stash of commonly-used offsets */
 	long module_memory_size;
 	long irq_data_irq;
 	long zspage_huge;
+	long zram_comp_algs;
 };
 
 struct size_table {         /* stash of commonly-used sizes */
diff --git a/diskdump.c b/diskdump.c
index 0fe46f4644d0..25054d96313e 100644
--- a/diskdump.c
+++ b/diskdump.c
@@ -2757,6 +2757,8 @@ diskdump_device_dump_info(FILE *ofp)
 
 static ulong ZRAM_FLAG_SHIFT;
 static ulong ZRAM_FLAG_SAME_BIT;
+static ulong ZRAM_COMP_PRIORITY_BIT1;
+static ulong ZRAM_COMP_PRIORITY_MASK;
 
 static void
 zram_init(void)
@@ -2765,6 +2767,8 @@ zram_init(void)
 
 	MEMBER_OFFSET_INIT(zram_mempoll, "zram", "mem_pool");
 	MEMBER_OFFSET_INIT(zram_compressor, "zram", "compressor");
+	if (INVALID_MEMBER(zram_compressor))
+		MEMBER_OFFSET_INIT(zram_comp_algs, "zram", "comp_algs");
 	MEMBER_OFFSET_INIT(zram_table_flag, "zram_table_entry", "flags");
 	if (INVALID_MEMBER(zram_table_flag))
 		MEMBER_OFFSET_INIT(zram_table_flag, "zram_table_entry", "value");
@@ -2782,6 +2786,8 @@ zram_init(void)
 
 	ZRAM_FLAG_SHIFT = 1 << zram_flag_shift;
 	ZRAM_FLAG_SAME_BIT = 1 << (zram_flag_shift+1);
+	ZRAM_COMP_PRIORITY_BIT1 = ZRAM_FLAG_SHIFT + 7;
+	ZRAM_COMP_PRIORITY_MASK = 0x3;
 
 	if (CRASHDEBUG(1))
 		fprintf(fp, "zram_flag_shift: %ld\n", zram_flag_shift);
@@ -2981,9 +2987,9 @@ try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulonglong
 	ulong zram, zram_table_entry, sector, index, entry, flags, size,
 		outsize, off;
 
-	if (INVALID_MEMBER(zram_compressor)) {
+	if (INVALID_MEMBER(zram_mempoll)) {
 		zram_init();
-		if (INVALID_MEMBER(zram_compressor)) {
+		if (INVALID_MEMBER(zram_mempoll)) {
 			error(WARNING,
 			      "Some pages are swapped out to zram. "
 			      "Please run mod -s zram.\n");
@@ -2997,8 +3003,28 @@ try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulonglong
 	if (!get_disk_name_private_data(pte_val, vaddr, NULL, &zram))
 		return 0;
 
-	readmem(zram + OFFSET(zram_compressor), KVADDR, name,
-		sizeof(name), "zram compressor", FAULT_ON_ERROR);
+	if (THIS_KERNEL_VERSION >= LINUX(2, 6, 0))
+		swp_offset = (ulonglong)__swp_offset(pte_val);
+	else
+		swp_offset = (ulonglong)SWP_OFFSET(pte_val);
+
+	sector = swp_offset << (PAGESHIFT() - 9);
+	index = sector >> SECTORS_PER_PAGE_SHIFT;
+	readmem(zram, KVADDR, &zram_table_entry,
+		sizeof(void *), "zram_table_entry", FAULT_ON_ERROR);
+	zram_table_entry += (index * SIZE(zram_table_entry));
+	readmem(zram_table_entry + OFFSET(zram_table_flag), KVADDR, &flags,
+		sizeof(void *), "zram_table_flag", FAULT_ON_ERROR);
+	if (VALID_MEMBER(zram_compressor))
+		readmem(zram + OFFSET(zram_compressor), KVADDR, name, sizeof(name),
+			"zram compressor", FAULT_ON_ERROR);
+	else {
+		ulong comp_alg_addr;
+		uint32_t prio = (flags >> ZRAM_COMP_PRIORITY_BIT1) & ZRAM_COMP_PRIORITY_MASK;
+		readmem(zram + OFFSET(zram_comp_algs) + sizeof(const char *) * prio, KVADDR,
+			&comp_alg_addr, sizeof(comp_alg_addr), "zram comp_algs", FAULT_ON_ERROR);
+		read_string(comp_alg_addr, name, sizeof(name));
+	}
 	if (STREQ(name, "lzo")) {
 #ifdef LZO
 		if (!(dd->flags & LZO_SUPPORTED)) {
@@ -3019,12 +3045,6 @@ try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulonglong
 		return 0;
 	}
 
-	if (THIS_KERNEL_VERSION >= LINUX(2, 6, 0)) {
-		swp_offset = (ulonglong)__swp_offset(pte_val);
-	} else {
-		swp_offset = (ulonglong)SWP_OFFSET(pte_val);
-	}
-
 	zram_buf = (unsigned char *)GETBUF(PAGESIZE());
 	/* lookup page from swap cache */
 	off = PAGEOFFSET(vaddr);
@@ -3034,15 +3054,8 @@ try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulonglong
 		goto out;
 	}
 
-	sector = swp_offset << (PAGESHIFT() - 9);
-	index = sector >> SECTORS_PER_PAGE_SHIFT;
-	readmem(zram, KVADDR, &zram_table_entry,
-		sizeof(void *), "zram_table_entry", FAULT_ON_ERROR);
-	zram_table_entry += (index * SIZE(zram_table_entry));
 	readmem(zram_table_entry, KVADDR, &entry,
 		sizeof(void *), "entry of table", FAULT_ON_ERROR);
-	readmem(zram_table_entry + OFFSET(zram_table_flag), KVADDR, &flags,
-		sizeof(void *), "zram_table_flag", FAULT_ON_ERROR);
 	if (!entry || (flags & ZRAM_FLAG_SAME_BIT)) {
 		int count;
 		ulong *same_buf = (ulong *)GETBUF(PAGESIZE());
-- 
2.41.0