2019-08-12 09:24:25

by Santosh Sivaraj

Subject: [PATCH v9 4/7] extable: Add function to search only kernel exception table

Certain architecture specific operating modes (e.g., in powerpc machine
check handler that is unable to access vmalloc memory), the
search_exception_tables cannot be called because it also searches the
module exception tables if entry is not found in the kernel exception
table.

Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Signed-off-by: Santosh Sivaraj <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
---
include/linux/extable.h | 2 ++
kernel/extable.c | 11 +++++++++--
2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/linux/extable.h b/include/linux/extable.h
index 41c5b3a25f67..81ecfaa83ad3 100644
--- a/include/linux/extable.h
+++ b/include/linux/extable.h
@@ -19,6 +19,8 @@ void trim_init_extable(struct module *m);

/* Given an address, look for it in the exception tables */
const struct exception_table_entry *search_exception_tables(unsigned long add);
+const struct exception_table_entry *
+search_kernel_exception_table(unsigned long addr);

#ifdef CONFIG_MODULES
/* For extable.c to search modules' exception tables. */
diff --git a/kernel/extable.c b/kernel/extable.c
index e23cce6e6092..f6c9406eec7d 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -40,13 +40,20 @@ void __init sort_main_extable(void)
}
}

+/* Given an address, look for it in the kernel exception table */
+const
+struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
+{
+ return search_extable(__start___ex_table,
+ __stop___ex_table - __start___ex_table, addr);
+}
+
/* Given an address, look for it in the exception tables. */
const struct exception_table_entry *search_exception_tables(unsigned long addr)
{
const struct exception_table_entry *e;

- e = search_extable(__start___ex_table,
- __stop___ex_table - __start___ex_table, addr);
+ e = search_kernel_exception_table(addr);
if (!e)
e = search_module_extables(addr);
return e;
--
2.21.0

2019-08-14 09:23:16

by Balbir Singh

Subject: Re: [PATCH v9 4/7] extable: Add function to search only kernel exception table

On 12/8/19 7:22 pm, Santosh Sivaraj wrote:
> Certain architecture specific operating modes (e.g., in powerpc machine
> check handler that is unable to access vmalloc memory), the
> search_exception_tables cannot be called because it also searches the
> module exception tables if entry is not found in the kernel exception
> table.
>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Nicholas Piggin <[email protected]>
> Signed-off-by: Santosh Sivaraj <[email protected]>
> Reviewed-by: Nicholas Piggin <[email protected]>
> ---
> include/linux/extable.h | 2 ++
> kernel/extable.c | 11 +++++++++--
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/extable.h b/include/linux/extable.h
> index 41c5b3a25f67..81ecfaa83ad3 100644
> --- a/include/linux/extable.h
> +++ b/include/linux/extable.h
> @@ -19,6 +19,8 @@ void trim_init_extable(struct module *m);
>
> /* Given an address, look for it in the exception tables */
> const struct exception_table_entry *search_exception_tables(unsigned long add);
> +const struct exception_table_entry *
> +search_kernel_exception_table(unsigned long addr);
>

Can we find a better name search_kernel still sounds like all of the kernel.
Can we rename it to search_kernel_linear_map_extable?


> #ifdef CONFIG_MODULES
> /* For extable.c to search modules' exception tables. */
> diff --git a/kernel/extable.c b/kernel/extable.c
> index e23cce6e6092..f6c9406eec7d 100644
> --- a/kernel/extable.c
> +++ b/kernel/extable.c
> @@ -40,13 +40,20 @@ void __init sort_main_extable(void)
> }
> }
>
> +/* Given an address, look for it in the kernel exception table */
> +const
> +struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
> +{
> + return search_extable(__start___ex_table,
> + __stop___ex_table - __start___ex_table, addr);
> +}
> +
> /* Given an address, look for it in the exception tables. */
> const struct exception_table_entry *search_exception_tables(unsigned long addr)
> {
> const struct exception_table_entry *e;
>
> - e = search_extable(__start___ex_table,
> - __stop___ex_table - __start___ex_table, addr);
> + e = search_kernel_exception_table(addr);
> if (!e)
> e = search_module_extables(addr);
> return e;
>

2019-08-14 09:41:34

by Santosh Sivaraj

Subject: Re: [PATCH v9 4/7] extable: Add function to search only kernel exception table

Balbir Singh <[email protected]> writes:

> On 12/8/19 7:22 pm, Santosh Sivaraj wrote:
>> Certain architecture specific operating modes (e.g., in powerpc machine
>> check handler that is unable to access vmalloc memory), the
>> search_exception_tables cannot be called because it also searches the
>> module exception tables if entry is not found in the kernel exception
>> table.
>>
>> Cc: Thomas Gleixner <[email protected]>
>> Cc: Ingo Molnar <[email protected]>
>> Cc: Nicholas Piggin <[email protected]>
>> Signed-off-by: Santosh Sivaraj <[email protected]>
>> Reviewed-by: Nicholas Piggin <[email protected]>
>> ---
>> include/linux/extable.h | 2 ++
>> kernel/extable.c | 11 +++++++++--
>> 2 files changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/extable.h b/include/linux/extable.h
>> index 41c5b3a25f67..81ecfaa83ad3 100644
>> --- a/include/linux/extable.h
>> +++ b/include/linux/extable.h
>> @@ -19,6 +19,8 @@ void trim_init_extable(struct module *m);
>>
>> /* Given an address, look for it in the exception tables */
>> const struct exception_table_entry *search_exception_tables(unsigned long add);
>> +const struct exception_table_entry *
>> +search_kernel_exception_table(unsigned long addr);
>>
>
> Can we find a better name search_kernel still sounds like all of the kernel.
> Can we rename it to search_kernel_linear_map_extable?

I thought search_kernel_exception_table and search_module_extables were
non-ambiguous enough :-) But If you think name will be confusing, I can
change that as suggested.

Thanks,
Santosh

>
>
>> #ifdef CONFIG_MODULES
>> /* For extable.c to search modules' exception tables. */
>> diff --git a/kernel/extable.c b/kernel/extable.c
>> index e23cce6e6092..f6c9406eec7d 100644
>> --- a/kernel/extable.c
>> +++ b/kernel/extable.c
>> @@ -40,13 +40,20 @@ void __init sort_main_extable(void)
>> }
>> }
>>
>> +/* Given an address, look for it in the kernel exception table */
>> +const
>> +struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
>> +{
>> + return search_extable(__start___ex_table,
>> + __stop___ex_table - __start___ex_table, addr);
>> +}
>> +
>> /* Given an address, look for it in the exception tables. */
>> const struct exception_table_entry *search_exception_tables(unsigned long addr)
>> {
>> const struct exception_table_entry *e;
>>
>> - e = search_extable(__start___ex_table,
>> - __stop___ex_table - __start___ex_table, addr);
>> + e = search_kernel_exception_table(addr);
>> if (!e)
>> e = search_module_extables(addr);
>> return e;
>>

--
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