Re: [bigmem-patch] 4GB with Linux on IA32

Jakub Jelinek
1999-08-17T08:52:03Z

On Tue, Aug 17, 1999 at 12:47:50AM +0200, Andrea Arcangeli wrote:
> This incremental (against bigmem-2.3.13-L) patch will fix the ptrace and
> /proc/*/mem read/writes to other process VM inside the kernel.

Isn't it cleaner to provided asm/bigmem.h on all platforms and even on
asm-i386 do something like

#ifndef CONFIG_BIGMEM
#define PageBIGMEM(map) 0
#define kmap(x,y) x
#define kunmap(x,y)
#else
...
#endif
?
>
> diff -urN 2.3.13-bigmem-L/fs/proc/mem.c tmp/fs/proc/mem.c
> --- 2.3.13-bigmem-L/fs/proc/mem.c Tue Jul 13 02:02:09 1999
> +++ tmp/fs/proc/mem.c Tue Aug 17 00:02:48 1999
> @@ -15,6 +15,9 @@
> #include <asm/uaccess.h>
> #include <asm/io.h>
> #include <asm/pgtable.h>
> +#ifdef CONFIG_BIGMEM
> +#include <asm/bigmem.h>
> +#endif
>
> /*
> * mem_write isn't really a good idea right now. It needs
> @@ -120,7 +123,13 @@
> i = PAGE_SIZE-(addr & ~PAGE_MASK);
> if (i > scount)
> i = scount;
> +#ifdef CONFIG_BIGMEM
> + page = (char *) kmap((unsigned long) page, KM_READ);
> +#endif
> copy_to_user(tmp, page, i);
> +#ifdef CONFIG_BIGMEM
> + kunmap((unsigned long) page, KM_READ);
> +#endif
> addr += i;
> tmp += i;
> scount -= i;
> @@ -177,7 +186,13 @@
> i = PAGE_SIZE-(addr & ~PAGE_MASK);
> if (i > count)
> i = count;
> +#ifdef CONFIG_BIGMEM
> + page = (unsigned long) kmap((unsigned long) page, KM_WRITE);
> +#endif
> copy_from_user(page, tmp, i);
> +#ifdef CONFIG_BIGMEM
> + kunmap((unsigned long) page, KM_WRITE);
> +#endif
> addr += i;
> tmp += i;
> count -= i;
> diff -urN 2.3.13-bigmem-L/kernel/ptrace.c tmp/kernel/ptrace.c
> --- 2.3.13-bigmem-L/kernel/ptrace.c Thu Jul 22 01:07:28 1999
> +++ tmp/kernel/ptrace.c Tue Aug 17 00:02:40 1999
> @@ -13,6 +13,9 @@
>
> #include <asm/pgtable.h>
> #include <asm/uaccess.h>
> +#ifdef CONFIG_BIGMEM
> +#include <asm/bigmem.h>
> +#endif
>
> /*
> * Access another process' address space, one page at a time.
> @@ -52,7 +55,15 @@
> dst = src;
> src = buf;
> }
> +#ifdef CONFIG_BIGMEM
> + src = (void *) kmap((unsigned long) src, KM_READ);
> + dst = (void *) kmap((unsigned long) dst, KM_WRITE);
> +#endif
> memcpy(dst, src, len);
> +#ifdef CONFIG_BIGMEM
> + kunmap((unsigned long) src, KM_READ);
> + kunmap((unsigned long) dst, KM_WRITE);
> +#endif
> }
> flush_page_to_ram(page);
> return len;
>
> The /proc/*/mem read/write seems to not work though (maybe I am doing
> something wrong...).
>
> black:/home/andrea# cat /proc/1/mem
> cat: /proc/1/mem: No such process
>
> The same happens also on 2.2.11.
>
> Andrea
>
>
> -
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Cheers,
Jakub
___________________________________________________________________
Jakub Jelinek | jj@sunsite.mff.cuni.cz | http://sunsite.mff.cuni.cz
Administrator of SunSITE Czech Republic, MFF, Charles University
___________________________________________________________________
UltraLinux | http://ultra.linux.cz/ | http://ultra.penguin.cz/
Linux version 2.3.13 on a sparc64 machine (1343.49 BogoMips)
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