[Crash-utility] 答复: [External Mail]Re: zram decompress support for gcore/crash-utility
Dave Anderson
anderson at redhat.com
Mon Apr 6 14:38:26 UTC 2020
----- Original Message -----
> patch update
> Found a better way translate pfn to page,PTOB.
> Besides,fix a issue with low probability of decompression failure
>
The changes to defs.h and memory.c look good. My comments for diskdump.c
are interspersed below, where many of them are redundant:
+#ifdef LZO
+static unsigned char *zram_object_addr(ulong pool, ulong handle, unsigned char *zram_buf)
+{
+ ulong obj, off, class, page, zspage;
+ struct zspage zspage_s;
+ physaddr_t paddr;
+ unsigned int obj_idx, class_idx, size;
+ ulong pages[2], sizes[2];
+
+ readmem(handle, KVADDR, &obj, sizeof(void *), "readmem address", RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ obj >>= OBJ_TAG_BITS;
+ phys_to_page(PTOB(obj >> OBJ_INDEX_BITS), &page);
+ obj_idx = (obj & OBJ_INDEX_MASK);
+
+ readmem(page + OFFSET(page_private), KVADDR, &zspage,
+ sizeof(void *), "readmem address", RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ readmem(zspage, KVADDR, &zspage_s, sizeof(struct zspage), "readmem address",RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+
+ class_idx = zspage_s.class;
+ if (zspage_s.magic != ZSPAGE_MAGIC)
+ error(FATAL, "zspage magic incorrect:0x%x\n", zspage_s.magic);
+
+ class = pool + OFFSET(zspoll_size_class);
+ class += (class_idx * sizeof(void *));
+ readmem(class, KVADDR, &class, sizeof(void *), "readmem address",RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ readmem(class + OFFSET(size_class_size), KVADDR,
+ &size, sizeof(unsigned int), "readmem address", RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ off = (size * obj_idx) & (~machdep->pagemask);
+ if (off + size <= PAGESIZE()) {
+ if (!is_page_ptr(page, &paddr)) {
+ error(WARNING, "zspage not a page pointer:%lx\n", page);
+ return NULL;
+ }
+ readmem(paddr + off, PHYSADDR, zram_buf, size, "readmem zram buffer", RETURN_ON_ERROR);
+ goto out;
+ }
+
+ pages[0] = page;
+ readmem(page + OFFSET(page_freelist), KVADDR, &pages[1],
+ sizeof(void *), "readmem address",RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ sizes[0] = PAGESIZE() - off;
+ sizes[1] = size - sizes[0];
+ if (!is_page_ptr(pages[0], &paddr)) {
+ error(WARNING, "pages[0] not a page pointer\n");
Maybe display the bogus value in pages[0] in the message?
+ return NULL;
+ }
+
+ readmem(paddr + off, PHYSADDR, zram_buf, sizes[0], "readmem zram buffer", RETURN_ON_ERROR);
+ if (!is_page_ptr(pages[1], &paddr)) {
+ error(WARNING, "pages[1] not a page pointer\n");
Maybe display the bogus value in pages[1] in the message?
+ return NULL;
+ }
+
+ readmem(paddr, PHYSADDR, zram_buf + sizes[0], sizes[1], "readmem zram buffer", RETURN_ON_ERROR);
+
+out:
+ readmem(page, KVADDR, &obj, sizeof(void *), "readmem address",RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ if (!(obj & (1<<10))) { //PG_OwnerPriv1 flag
+ return (zram_buf + ZS_HANDLE_SIZE);
+ }
+
+ return zram_buf;
+}
+
+static unsigned char *lookup_swap_cache(ulong pte_val, unsigned char *zram_buf)
+{
+ ulong swp_type, swp_offset, swp_space;
+ struct list_pair lp;
+ physaddr_t paddr;
+ swp_type = __swp_type(pte_val);
+ if (THIS_KERNEL_VERSION >= LINUX(2,6,0)) {
+ swp_offset = (ulonglong)__swp_offset(pte_val);
+ } else {
+ swp_offset = (ulonglong)SWP_OFFSET(pte_val);
+ }
+
+ if (!symbol_exists("swapper_spaces"))
+ return NULL;
+ swp_space = symbol_value("swapper_spaces");
+ swp_space += swp_type * sizeof(void *);
+
+ readmem(swp_space, KVADDR, &swp_space, sizeof(void *),
+ "readmem address",RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ swp_space += (swp_offset >> SWAP_ADDRESS_SPACE_SHIFT) * SIZE(address_space);
+
+ lp.index = swp_offset;
+ if (do_radix_tree(swp_space, RADIX_TREE_SEARCH, &lp)){
+ fprintf(fp, "Find page in swap cache\n");
I don't think you meant to leave this message, right?
+ if (!is_page_ptr((ulong)lp.value, &paddr)) {
+ error(WARNING, "radix page not a page pointer\n");
+ return NULL;
+ }
+ readmem(paddr, PHYSADDR, zram_buf, PAGESIZE(), "readmem zram buffer", RETURN_ON_ERROR);
+ return zram_buf;
+ }
+ return NULL;
+}
+
+ulong (*decompressor)(unsigned char *in_addr, ulong in_size, unsigned char *out_addr, ulong *out_size, void *other/* NOT USED */);
+/*
+try_zram_decompress returns decompressed page data and data length
+If userspace address was swaped out to zram,call this function to decompress this object.
+*/
+ulong try_zram_decompress(ulong pte_val, unsigned char *buf, ulong len, uint32_t off)
+{
+ char name[32] = {0};
+ ulonglong swp_offset;
+ ulong swap_info, bdev, bd_disk, zram, zram_table_entry, sector, index, entry, flags, size, outsize;
+ unsigned char *obj_addr = NULL;
+ unsigned char *zram_buf = NULL;
+ unsigned char *outbuf = NULL;
+
+
+ if (!symbol_exists("swap_info"))
+ return 0;
+
+ swap_info = symbol_value("swap_info");
+
+ swap_info_init();
+ if (vt->flags & SWAPINFO_V2) {
+ swap_info += (__swp_type(pte_val) * sizeof(void *));
+ readmem(swap_info, KVADDR, &swap_info,
+ sizeof(void *), "readmem address", RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ } else {
+ swap_info += (SIZE(swap_info_struct) * __swp_type(pte_val));
+ }
+
+ readmem(swap_info + OFFSET(swap_info_struct_bdev), KVADDR, &bdev,
+ sizeof(void *), "read swap_info_struct_bdev", RETURN_ON_ERROR);
+ readmem(bdev + OFFSET(block_device_bd_disk), KVADDR, &bd_disk,
+ sizeof(void *), "read block_device_bd_disk", RETURN_ON_ERROR);
+ readmem(bd_disk + OFFSET(gendisk_disk_name), KVADDR, name,
+ strlen("zram"), "read gendisk_disk_name", RETURN_ON_ERROR);
+ if (!strncmp(name, "zram", strlen("zram"))) {
+ if (CRASHDEBUG(2))
+ error(WARNING, "This page has swaped to zram\n");
+
+ readmem(bd_disk + OFFSET(gendisk_private_data), KVADDR, &zram,
+ sizeof(void *), "gendisk_private_data", RETURN_ON_ERROR);
+
+ readmem(zram + OFFSET(zram_compressor), KVADDR, name,
+ sizeof(name), "zram compressor", RETURN_ON_ERROR);
+ if (!strncmp(name, "lzo", strlen("lzo"))) {
+ if (!(dd->flags & LZO_SUPPORTED)) {
+ if (lzo_init() == LZO_E_OK)
+ dd->flags |= LZO_SUPPORTED;
+ else
+ return 0;
+ }
+ decompressor = (void *)lzo1x_decompress_safe;
+ } else {//todo,support more compressor
+ error(WARNING, "Only support lzo compressor\n");
+ 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);
+ }
+
+ if ((zram_buf = (unsigned char*)malloc(PAGESIZE())) == NULL)
+ error(FATAL, "cannot malloc zram_buf space.");
Never use malloc/free for temporary buffers during runtime. Either use GETBUF()/FREEBUF()
or just put it on the stack.
+
+ /*lookup page from swap cache*/
+ obj_addr = lookup_swap_cache(pte_val, zram_buf);
+ if (obj_addr != NULL) {
+ memcpy(buf, obj_addr + off, len);
+ goto out;
+ }
+
+ sector = swp_offset << (PAGESHIFT() - 9);
+ index = sector >> SECTORS_PER_PAGE_SHIFT;
+ readmem(zram, KVADDR, &zram_table_entry,
+ sizeof(void *), "readmem address", RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ zram_table_entry += (index * SIZE(zram_table_entry));
+ readmem(zram_table_entry, KVADDR, &entry,
+ sizeof(void *), "readmem address", RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ readmem(zram_table_entry + OFFSET(zram_table_flag), KVADDR, &flags,
+ sizeof(void *), "readmem address", RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+ if (!entry || (flags & ZRAM_FLAG_SAME_BIT)) {
+ memset(buf, entry, len);
+ goto out;
+ }
+ size = flags & (ZRAM_FLAG_SHIFT -1);
+ if (size == 0) {
+ len = 0;
+ goto out;
+ }
+
+ readmem(zram + OFFSET(zram_mempoll), KVADDR, &zram,
+ sizeof(void *), "readmem address", RETURN_ON_ERROR);
Can you make the error message type string something more helpful than "readmem address"?
+
+ obj_addr = zram_object_addr(zram, entry, zram_buf);
+ if (obj_addr == NULL) {
+ len = 0;
+ goto out;
+ }
+
+ if (size == PAGESIZE()) {
+ memcpy(buf, obj_addr + off, len);
+ } else {
+ if ((outbuf = (unsigned char*)malloc(PAGESIZE())) == NULL)
+ error(FATAL, "cannot malloc outbuf space.");
Never use malloc/free for temporary buffers during runtime. Either use GETBUF()/FREEBUF()
or just put it on the stack.
+
+ if (!decompressor(obj_addr, size, outbuf, &outsize, NULL))
+ memcpy(buf, outbuf + off, len);
+ else {
+ error(WARNING, "zram decompress error\n");
+ len = 0;
+ }
+ free(outbuf);
+ }
+ }
+
+out:
+ free(zram_buf);
+ return len;
+}
+#else
+ulong try_zram_decompress(ulong pte_val, unsigned char *buf, ulong len, uint32_t off)
+{
+ return 0;
+}
+#endif
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