linux-kernel - two bugletts on sparc - Dave Miller is always right, isn't he? :-)))

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Message-ID: <DA6197CAE190A847B662079EF7631C060156929E@OEKAW2EXVS03.hbi.ad.harman.com>
Date:	Fri, 25 Aug 2006 16:40:41 +0200
From:	"Jurzitza, Dieter" <DJurzitza@...manbecker.com>
To:	<linux-kernel@...r.kernel.org>, <sparclinux@...r.kernel.org>
Subject: two bugletts on sparc - Dave Miller is always right, isn't he? :-)))

Dear listmembers,
thanks to the inputs to David Miller there is a fix for the kmalloc issue with sys32_get_kernel_syms() in linux/arch/sparc64/kernel/sys_sparc32.c, preventing the kernel from reading the entire symbol table due to a memory limitation.

Rather than my initial suggestion to change the unsigned long to an unsigned int in struct kernel_syms, the kmalloc() should be changed into a vmalloc() giving significant improvement with regard to the max amount of symbols that can be read. So, I would suggest (tested on my U60) to integrate the following patch into the kernel 2.4-tree (cannot tell about 2.6). I would expect similar issues on other 32/64 arches, but cannot test. x86_64 contains the very same function with the very same call in linux/arc/x86_64/kernel/ia32/sys_ia32.c.

The number of symbols that can be read by sys32_get_kernel_syms is limited to 2048 at max, what is not enough IMHO. Dave Miller suggested to replace the kmalloc() by a vmalloc(), this should be uncritical here as I do not think the delay is of significance. This increases the memsize-limit from 2^17 i. e. 128k to several MByte, what should be sufficient.

Successfully tested here (kernel 2.4.33):

--- linux/arch/sparc64/kernel/sys_sparc32.c     2006-08-11 06:18:20.000000000 +
+++ linux/arch/sparc64/kernel/sys_sparc32.c     2006-08-25 12:37:42.000000000 +
@@ -3730,7 +3730,7 @@

        len = sys_get_kernel_syms(NULL);
        if (!table) return len;
-       tbl = kmalloc (len * sizeof (struct kernel_sym), GFP_KERNEL);
+       tbl = vmalloc (len * sizeof (struct kernel_sym));
        if (!tbl) return -ENOMEM;
        old_fs = get_fs(); 
        set_fs (KERNEL_DS);
@@ -3741,7 +3741,7 @@
                    copy_to_user (table->name, tbl[i].name, 60))
                        break;
        }
-       kfree (tbl);
+       vfree (tbl);
        return i;
 }

Thanks to Dave Miller once again,
take care

Dieter Jurzitza

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