[PATCH] module: Remove a extra null character at the top of module->strtab.
From: Satoru Takeuchi
There is a extra null character('\0') at the top of module->strtab for
each module. Commit 59ef28b introduced this bug and this patch fixes it.
Live dump log of the current linus git kernel(HEAD is 2844a4870):
crash> mod | grep loop
a01db0a0 loop 16689 (not loaded) [CONFIG_KALLSYMS]
crash> module.core_symtab a01db0a0
core_symtab = 0xa01db320crash> rd 0xa01db320 12
a01db320: 00550001 U...
a01db330: 000200740002 t...
a01db340: a01d8000 0038 8...
a01db350: 001a0064000e a01daeb0 d...
a01db360: 00a0 000200740019 t...
a01db370: a01d8068 001b h...
crash> module.core_strtab a01db0a0
core_strtab = 0xa01dbb30 ""
crash> rd 0xa01dbb30 4
a01dbb30: 615f70616d6b 66780063696d6f74 ..kmap_atomic.xf
a01dbb40: 73636e75665f7265 72665f646e696600 er_funcs.find_fr
We expect Just first one byte of '\0', but actually first two bytes
are '\0'. Here is The relationship between symtab and strtab.
symtab_idx strtab_idx symbol
---
0 0x1 "\0" # startab_idx should be 0
1 0x2 "kmap_atomic"
2 0xe "xfer_funcs"
3 0x19"find_fr..."
By applying this patch, it becomes as follows.
symtab_idx strtab_idx symbol
---
0 0x0 "\0"# extra byte is removed
1 0x1 "kmap_atomic"
2 0xd "xfer_funcs"
3 0x18"find_fr..."
Signed-off-by: Satoru Takeuchi
Cc: Masaki Kimura
Cc: Rusty Russell
Cc: Greg Kroah-Hartman
---
kernel/module.c |6 +-
1 files changed, 1 insertions(+), 5 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index 6e48c3a..7af5d5d 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2282,7 +2282,7 @@ static void layout_symtab(struct module *mod, struct
load_info *info)
Elf_Shdr *symsect = info->sechdrs + info->index.sym;
Elf_Shdr *strsect = info->sechdrs + info->index.str;
const Elf_Sym *src;
- unsigned int i, nsrc, ndst, strtab_size;
+ unsigned int i, nsrc, ndst, strtab_size = 0;
/* Put symbol section at end of init part of module. */
symsect->sh_flags |= SHF_ALLOC;
@@ -2293,9 +2293,6 @@ static void layout_symtab(struct module *mod, struct
load_info *info)
src = (void *)info->hdr + symsect->sh_offset;
nsrc = symsect->sh_size / sizeof(*src);
- /* strtab always starts with a nul, so offset 0 is the empty string. */
- strtab_size = 1;
-
/* Compute total space required for the core symbols' strtab. */
for (ndst = i = 0; i < nsrc; i++) {
if (i == 0 ||
@@ -2337,7 +2334,6 @@ static void add_kallsyms(struct module *mod, const struct
load_info *info)
mod->core_symtab = dst = mod->module_core + info->symoffs;
mod->core_strtab = s = mod->module_core + info->stroffs;
src = mod->symtab;
- *s++ = 0;
for (ndst = i = 0; i < mod->num_symtab; i++) {
if (i == 0 ||
is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) {
-- 1.7.2.5
--
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[PATCH] module: Remove a extra null character at the top of module-strtab.
From: Satoru Takeuchi takeuchi_sat...@jp.fujitsu.com
There is a extra null character('\0') at the top of module-strtab for
each module. Commit 59ef28b introduced this bug and this patch fixes it.
Live dump log of the current linus git kernel(HEAD is 2844a4870):
crash mod | grep loop
a01db0a0 loop 16689 (not loaded) [CONFIG_KALLSYMS]
crash module.core_symtab a01db0a0
core_symtab = 0xa01db320crash rd 0xa01db320 12
a01db320: 00550001 U...
a01db330: 000200740002 t...
a01db340: a01d8000 0038 8...
a01db350: 001a0064000e a01daeb0 d...
a01db360: 00a0 000200740019 t...
a01db370: a01d8068 001b h...
crash module.core_strtab a01db0a0
core_strtab = 0xa01dbb30
crash rd 0xa01dbb30 4
a01dbb30: 615f70616d6b 66780063696d6f74 ..kmap_atomic.xf
a01dbb40: 73636e75665f7265 72665f646e696600 er_funcs.find_fr
We expect Just first one byte of '\0', but actually first two bytes
are '\0'. Here is The relationship between symtab and strtab.
symtab_idx strtab_idx symbol
---
0 0x1 \0 # startab_idx should be 0
1 0x2 kmap_atomic
2 0xe xfer_funcs
3 0x19find_fr...
By applying this patch, it becomes as follows.
symtab_idx strtab_idx symbol
---
0 0x0 \0# extra byte is removed
1 0x1 kmap_atomic
2 0xd xfer_funcs
3 0x18find_fr...
Signed-off-by: Satoru Takeuchi takeuchi_sat...@jp.fujitsu.com
Cc: Masaki Kimura masaki.kimura...@hitachi.com
Cc: Rusty Russell ru...@rustcorp.com.au
Cc: Greg Kroah-Hartman gre...@linuxfoundation.org
---
kernel/module.c |6 +-
1 files changed, 1 insertions(+), 5 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index 6e48c3a..7af5d5d 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2282,7 +2282,7 @@ static void layout_symtab(struct module *mod, struct
load_info *info)
Elf_Shdr *symsect = info-sechdrs + info-index.sym;
Elf_Shdr *strsect = info-sechdrs + info-index.str;
const Elf_Sym *src;
- unsigned int i, nsrc, ndst, strtab_size;
+ unsigned int i, nsrc, ndst, strtab_size = 0;
/* Put symbol section at end of init part of module. */
symsect-sh_flags |= SHF_ALLOC;
@@ -2293,9 +2293,6 @@ static void layout_symtab(struct module *mod, struct
load_info *info)
src = (void *)info-hdr + symsect-sh_offset;
nsrc = symsect-sh_size / sizeof(*src);
- /* strtab always starts with a nul, so offset 0 is the empty string. */
- strtab_size = 1;
-
/* Compute total space required for the core symbols' strtab. */
for (ndst = i = 0; i nsrc; i++) {
if (i == 0 ||
@@ -2337,7 +2334,6 @@ static void add_kallsyms(struct module *mod, const struct
load_info *info)
mod-core_symtab = dst = mod-module_core + info-symoffs;
mod-core_strtab = s = mod-module_core + info-stroffs;
src = mod-symtab;
- *s++ = 0;
for (ndst = i = 0; i mod-num_symtab; i++) {
if (i == 0 ||
is_core_symbol(src+i, info-sechdrs, info-hdr-e_shnum)) {
-- 1.7.2.5
--
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Please read the FAQ at http://www.tux.org/lkml/
Re: what will connect the fork() with its following code ? a simple example below:
here is a snip in 0.11 version linux ,
in linux/init/main.c
179 if (!(pid=fork())) {
180 close(0);
181 if (open( "/etc/rc",O_RDONLY,0))
182 _exit(1);
183 execve( "/bin/sh",argv_rc,envp_rc);
184 _exit(2);
185 }
natually, the code from 180 to 184 is runned by the new process, what
I can understand is why the new process know that the next code will
run is close(0) and why it know It will end at line 184 ?
so ,I feel that there should be some connection between them . but
what the relationship in depth is ?
thanks your help :)
2005/9/6, Dirk Gerdes <[EMAIL PROTECTED]>:
> There is no connection between a child an its parent.
> The child only gets a copy of the code.
> If there were a pointer to a child or to the parent, you wouldn't need any
> signals.
> The processes could communicate directly.
>
> regards
>
> - Original Message -
> From: "Sat." <[EMAIL PROTECTED]>
> To:
> Sent: Tuesday, September 06, 2005 11:15 AM
> Subject: what will connect the fork() with its following code ? a simple
> example below:
>
>
> > if(!(pid=fork())){
> > ..
> > printk("in child process");
> > ..
> > }else{
> > .
> > printk("in father process");
> > .
> > }
> >
> > this is a classical example, when the fork() system call runs, it will
> > build a new process and active it . while the schedule() select the
> > new process it will run. this is rather normal.
> >
> > but there is always a confusion in my minds.
> > because , sys_fork() only copies father process and configure some new
> > values., and do nothing . so the bridge between the new process and
> > its following code, printk("in child process"), seems disappear . so I
> > always believe that the new process should have a pointer which point
> > the code "printk("in child process");". except this , there are not
> > any connection between them ?
> >
> > very confused :(
> >
> > any help will appreciate !
> >
> >
> >
> > --
> > Sat.
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to [EMAIL PROTECTED]
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
> >
>
>
--
Sat.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: what will connect the fork() with its following code ? a simple example below:
here is a snip in 0.11 version linux ,
in linux/init/main.c
179 if (!(pid=fork())) {
180 close(0);
181 if (open( /etc/rc,O_RDONLY,0))
182 _exit(1);
183 execve( /bin/sh,argv_rc,envp_rc);
184 _exit(2);
185 }
natually, the code from 180 to 184 is runned by the new process, what
I can understand is why the new process know that the next code will
run is close(0) and why it know It will end at line 184 ?
so ,I feel that there should be some connection between them . but
what the relationship in depth is ?
thanks your help :)
2005/9/6, Dirk Gerdes [EMAIL PROTECTED]:
There is no connection between a child an its parent.
The child only gets a copy of the code.
If there were a pointer to a child or to the parent, you wouldn't need any
signals.
The processes could communicate directly.
regards
- Original Message -
From: Sat. [EMAIL PROTECTED]
To: linux-kernel@vger.kernel.org
Sent: Tuesday, September 06, 2005 11:15 AM
Subject: what will connect the fork() with its following code ? a simple
example below:
if(!(pid=fork())){
..
printk(in child process);
..
}else{
.
printk(in father process);
.
}
this is a classical example, when the fork() system call runs, it will
build a new process and active it . while the schedule() select the
new process it will run. this is rather normal.
but there is always a confusion in my minds.
because , sys_fork() only copies father process and configure some new
values., and do nothing . so the bridge between the new process and
its following code, printk(in child process), seems disappear . so I
always believe that the new process should have a pointer which point
the code printk(in child process);. except this , there are not
any connection between them ?
very confused :(
any help will appreciate !
--
Sat.
-
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
--
Sat.
-
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to [EMAIL PROTECTED]
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Please read the FAQ at http://www.tux.org/lkml/
Re: when or where can the case occur in "linux kernel development " about "kernel preemption"?
2005/8/27, Christopher Friesen <[EMAIL PROTECTED]>: > Sat. wrote: > > the case about kernel preemption as follow : > > > > the book said "when a process that has a higher priority than the > > currenty running process is awakened ". > > > > but I can think about when such case can occur , could you give me an > > example ? > > There may be others, but one common case is when a hardware interrupt > causes the higher priority process to become runnable. Some examples of > this would be a network packet arriving, or the expiry of a hardware timer. > > Chris > unfortunately, I cannot agree with you , normally ,when the kernel runs in interrupt context , the schedule() should not be invoked --my views . then,could anyone give me a definite example about network like above or anything else to eluminate this , ok? thanks ! -- Sat. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: when or where can the case occur in linux kernel development about kernel preemption?
2005/8/27, Christopher Friesen [EMAIL PROTECTED]: Sat. wrote: the case about kernel preemption as follow : the book said when a process that has a higher priority than the currenty running process is awakened . but I can think about when such case can occur , could you give me an example ? There may be others, but one common case is when a hardware interrupt causes the higher priority process to become runnable. Some examples of this would be a network packet arriving, or the expiry of a hardware timer. Chris unfortunately, I cannot agree with you , normally ,when the kernel runs in interrupt context , the schedule() should not be invoked --my views . then,could anyone give me a definite example about network like above or anything else to eluminate this , ok? thanks ! -- Sat. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
