Re: [Crash-utility] using crash for ARM

Hi Dave, The section translation inside 'arm_vtop' function and getting to the physical address looks beyond my understanding. if (verbose) fprintf(fp, "PAGE DIRECTORY: %lx\n", (ulong)pgd); /* * pgd_offset(pgd, vaddr) */ page_dir = pgd + PGD_OFFSET(vaddr) * 2; FILL_PGD(PAGEBASE(pgd), KVADDR, PGDIR_SIZE()); pgd_pte = ULONG(machdep->pgd + PGDIR_OFFSET(page_dir)); if (verbose) fprintf(fp, " PGD: %s => %lx\n", mkstring(buf, VADDR_PRLEN, RJUST | LONG_HEX, MKSTR((ulong)page_dir)), pgd_pte); if (!pgd_pte) return FALSE; /* * pmd_offset(pgd, vaddr) * * Here PMD is folded into a PGD. */ pmd_pte = pgd_pte; page_middle = page_dir; if (verbose) fprintf(fp, " PMD: %s => %lx\n", mkstring(buf, VADDR_PRLEN, RJUST | LONG_HEX, MKSTR((ulong)page_middle)), pmd_pte); if ((pmd_pte & PMD_TYPE_MASK) == PMD_TYPE_SECT) { if (verbose) { fprintf(fp, " PAGE: %s (1MB)\n\n", mkstring(buf, VADDR_PRLEN, RJUST | LONG_HEX, MKSTR(PAGEBASE(pmd_pte)))); } *paddr = PAGEBASE(pmd_pte) + (vaddr & ~_SECTION_PAGE_MASK); return TRUE; } if you look at page_dir = pgd + PGD_OFFSET(vaddr) * 2; FILL_PGD(PAGEBASE(pgd), KVADDR, PGDIR_SIZE()); pgd_pte = ULONG(machdep->pgd + PGDIR_OFFSET(page_dir)); the final first level discriptor is not coming properly for kernel virtual address with [20st counting from 0....n] bit set. if you look at the following output: crash> vtop 0xc010005c VIRTUAL PHYSICAL c010005c 8210005c PAGE DIRECTORY: c0004000 PGD: c0007000 => 8200040e PMD: c0007000 => 8200040e PAGE: 82000000 (1MB) PAGE PHYSICAL MAPPING INDEX CNT FLAGS c103c000 82000000 c1d16f28 3 54 8027c crash> vtop 0xc000005c VIRTUAL PHYSICAL c000005c 8200005c PAGE DIRECTORY: c0004000 PGD: c0007000 => 8200040e PMD: c0007000 => 8200040e PAGE: 82000000 (1MB) PAGE PHYSICAL MAPPING INDEX CNT FLAGS c103c000 82000000 c1d16f28 3 54 8027c virtual to physical mapping is fine, because it doesnt even go through arm_vtop() function. as it is straight one to one mapping, you use VTOP macro. so basically section code snippet which I sent you never come into picture. if you have a look at the both kernel virtual addresses 0xc010005c and 0xc000005c both are 1MB apart. but still following contents are same. PAGE DIRECTORY: c0004000 PGD: c0007000 => 8200040e PMD: c0007000 => 8200040e PAGE: 82000000 (1MB) I shall clarify more, If you require more info. I hope I am not missing anything here. PS: If I want to have correct physical address corresponding to 0xc010005c then I have to do workaround for section level physical addresses as follows. page_dir = pgd + PGD_OFFSET(vaddr) * 2; if (bit(vaddr,20)) //if bit is set then move to the next pgd */ page_dir = page_dir + 1; FILL_PGD(PAGEBASE(pgd), KVADDR, PGDIR_SIZE()); pgd_pte = ULONG(machdep->pgd + PGDIR_OFFSET(page_dir)); Regards, Oza. From: Dave Anderson <anderson(a)redhat.com&gt; To: paawan oza <paawan1982(a)yahoo.com&gt; Cc: "Discussion list for crash utility usage, maintenance and development" <crash-utility(a)redhat.com&gt; Sent: Tuesday, 14 August 2012 7:46 PM Subject: Re: [Crash-utility] using crash for ARM ----- Original Message ----- > > > strings ./vmlinux | grep "Linux version" > Linux version 3.0.15+ (oza@lc-blr-291) (gcc version 4.4.3 (GCC) ) > #4 PREEMPT Mon Aug 13 12:02:58 IST 2012 > > cat /proc/version > Linux version 3.0.15+ (oza@lc-blr-291) (gcc version 4.4.3 (GCC) ) > #4 PREEMPT Mon Aug 13 12:02:58 IST 2012 Looks OK -- so you'll have to debug verify_namelist(). It does a popen("/usr/bin/strings ./vmlinux") and searches for the linux_banner string here: while (fgets(buffer, BUFSIZE-1, pipe)) { if (!strstr(buffer, "Linux version 2.") && !strstr(buffer, "Linux version 3.")) continue; and when it finds it, it picks out the gcc version number. I don't know why it's not working in your case. Also, since your vmlinux file is identical to /proc/version, why are you using a System.map argument again? > > crash> ptype struct kmem_cache > type = struct kmem_cache { > struct array_cache *array[1]; > unsigned int batchcount; > unsigned int limit; > unsigned int shared; > unsigned int buffer_size; > u32 reciprocal_buffer_size; > unsigned int flags; > unsigned int num; > unsigned int gfporder; > gfp_t gfpflags; > size_t colour; > unsigned int colour_off; > struct kmem_cache *slabp_cache; > unsigned int slab_size; > unsigned int dflags; > void (*ctor)(void *); > const char *name; > struct list_head next; > struct kmem_list3 *nodelists[1]; > } OK, in this case you'll have to debug get_array_length(), and figure out why it's not finding the lookfor2 string -- which should be set to "*array[" -- in the ptype command output. Again, I don't know why it's not finding it. Dave