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Message-Id: <20071029152228.78aa5f3e.akpm@linux-foundation.org>
Date: Mon, 29 Oct 2007 15:22:28 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Robin Getz <rgetz@...ckfin.uclinux.org>
Cc: jdl@...escale.com, dwmw2@...radead.org, paulus@...ba.org,
linux-kernel@...r.kernel.org
Subject: Re: [patch] remove support for un-needed _extratext section
On Fri, 26 Oct 2007 15:43:56 -0400
Robin Getz <rgetz@...ckfin.uclinux.org> wrote:
> From: Robin Getz <rgetz@...ckfin.uclinux.org>
>
> when passing a zero address to kallsyms_lookup(), the kernel thought it was a
> valid kernel address, even if it is not. This is because is_ksym_addr() called
> is_kernel_extratext() and checked against labels that don't exist on many
> archs (which default as zero). Since PPC was the only kernel which defines
> _extra_text, (in 2005), and no longer needs it, this patch removes _extra_text
> support.
I hit numerous rejects here. I am not sure which kernel you patched but I
suspect it was not an up-to-date one.
> --- kernel/kallsyms.c (revision 3780)
> +++ kernel/kallsyms.c (working copy)
Please prepare patches in `patch -p1' form. This should have been
--- foo/kernel/kallsyms.c (revision 3780)
+++ bar/kernel/kallsyms.c (working copy)
> */
> if ((s->addr == _etext && strcmp((char*)s->sym + offset, "_etext")) ||
> - (s->addr == _einittext && strcmp((char*)s->sym + offset, "_einittext")) ||
> - (s->addr == _eextratext && strcmp((char*)s->sym + offset, "_eextratext")))
> + (s->addr == _einittext && strcmp((char*)s->sym + offset, "_einittext")))
> return 0;
> }
I don't understand why this hunk is changing _einittext handling, and I
suspect this was a mistake, so I left that bit out.
I ended up with this:
From: Robin Getz <rgetz@...ckfin.uclinux.org>
When passing a zero address to kallsyms_lookup(), the kernel thought it was
a valid kernel address, even if it is not. This is because is_ksym_addr()
called is_kernel_extratext() and checked against labels that don't exist on
many archs (which default as zero). Since PPC was the only kernel which
defines _extra_text, (in 2005), and no longer needs it, this patch removes
_extra_text support.
For some history (provided by Jon):
http://ozlabs.org/pipermail/linuxppc-dev/2005-September/019734.html
http://ozlabs.org/pipermail/linuxppc-dev/2005-September/019736.html
http://ozlabs.org/pipermail/linuxppc-dev/2005-September/019751.html
Signed-off-by: Robin Getz <rgetz@...ckfin.uclinux.org>
Cc: David Woodhouse <dwmw2@...radead.org>
Cc: Jon Loeliger <jdl@...escale.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Sam Ravnborg <sam@...nborg.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
arch/ppc/kernel/vmlinux.lds.S | 5 -----
include/asm-generic/sections.h | 2 --
kernel/kallsyms.c | 11 +----------
scripts/kallsyms.c | 24 ++++++++++--------------
4 files changed, 11 insertions(+), 31 deletions(-)
diff -puN arch/ppc/kernel/vmlinux.lds.S~remove-support-for-un-needed-_extratext-section arch/ppc/kernel/vmlinux.lds.S
--- a/arch/ppc/kernel/vmlinux.lds.S~remove-support-for-un-needed-_extratext-section
+++ a/arch/ppc/kernel/vmlinux.lds.S
@@ -143,11 +143,6 @@ SECTIONS
. = ALIGN(4096);
__init_end = .;
-
- . = ALIGN(4096);
- _sextratext = .;
- _eextratext = .;
-
__bss_start = .;
.bss :
{
diff -puN include/asm-generic/sections.h~remove-support-for-un-needed-_extratext-section include/asm-generic/sections.h
--- a/include/asm-generic/sections.h~remove-support-for-un-needed-_extratext-section
+++ a/include/asm-generic/sections.h
@@ -8,8 +8,6 @@ extern char _data[], _sdata[], _edata[];
extern char __bss_start[], __bss_stop[];
extern char __init_begin[], __init_end[];
extern char _sinittext[], _einittext[];
-extern char _sextratext[] __attribute__((weak));
-extern char _eextratext[] __attribute__((weak));
extern char _end[];
extern char __per_cpu_start[], __per_cpu_end[];
extern char __kprobes_text_start[], __kprobes_text_end[];
diff -puN kernel/kallsyms.c~remove-support-for-un-needed-_extratext-section kernel/kallsyms.c
--- a/kernel/kallsyms.c~remove-support-for-un-needed-_extratext-section
+++ a/kernel/kallsyms.c
@@ -48,14 +48,6 @@ static inline int is_kernel_inittext(uns
return 0;
}
-static inline int is_kernel_extratext(unsigned long addr)
-{
- if (addr >= (unsigned long)_sextratext
- && addr <= (unsigned long)_eextratext)
- return 1;
- return 0;
-}
-
static inline int is_kernel_text(unsigned long addr)
{
if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext)
@@ -75,8 +67,7 @@ static int is_ksym_addr(unsigned long ad
if (all_var)
return is_kernel(addr);
- return is_kernel_text(addr) || is_kernel_inittext(addr) ||
- is_kernel_extratext(addr);
+ return is_kernel_text(addr) || is_kernel_inittext(addr);
}
/* expand a compressed symbol data into the resulting uncompressed string,
diff -puN scripts/kallsyms.c~remove-support-for-un-needed-_extratext-section scripts/kallsyms.c
--- a/scripts/kallsyms.c~remove-support-for-un-needed-_extratext-section
+++ a/scripts/kallsyms.c
@@ -41,7 +41,7 @@ struct sym_entry {
static struct sym_entry *table;
static unsigned int table_size, table_cnt;
-static unsigned long long _text, _stext, _etext, _sinittext, _einittext, _sextratext, _eextratext;
+static unsigned long long _text, _stext, _etext, _sinittext, _einittext;
static int all_symbols = 0;
static char symbol_prefix_char = '\0';
@@ -99,10 +99,6 @@ static int read_symbol(FILE *in, struct
_sinittext = s->addr;
else if (strcmp(sym, "_einittext") == 0)
_einittext = s->addr;
- else if (strcmp(sym, "_sextratext") == 0)
- _sextratext = s->addr;
- else if (strcmp(sym, "_eextratext") == 0)
- _eextratext = s->addr;
else if (toupper(stype) == 'A')
{
/* Keep these useful absolute symbols */
@@ -165,18 +161,18 @@ static int symbol_valid(struct sym_entry
* and inittext sections are discarded */
if (!all_symbols) {
if ((s->addr < _stext || s->addr > _etext)
- && (s->addr < _sinittext || s->addr > _einittext)
- && (s->addr < _sextratext || s->addr > _eextratext))
+ && (s->addr < _sinittext || s->addr > _einittext))
return 0;
/* Corner case. Discard any symbols with the same value as
- * _etext _einittext or _eextratext; they can move between pass
- * 1 and 2 when the kallsyms data are added. If these symbols
- * move then they may get dropped in pass 2, which breaks the
- * kallsyms rules.
+ * _etext _einittext; they can move between pass 1 and 2 when
+ * the kallsyms data are added. If these symbols move then
+ * they may get dropped in pass 2, which breaks the kallsyms
+ * rules.
*/
- if ((s->addr == _etext && strcmp((char*)s->sym + offset, "_etext")) ||
- (s->addr == _einittext && strcmp((char*)s->sym + offset, "_einittext")) ||
- (s->addr == _eextratext && strcmp((char*)s->sym + offset, "_eextratext")))
+ if ((s->addr == _etext &&
+ strcmp((char*)s->sym + offset, "_etext")) ||
+ (s->addr == _einittext &&
+ strcmp((char*)s->sym + offset, "_einittext")))
return 0;
}
_
-
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