linux.git/include/linux/kallsyms.h, branch v6.1

kallsyms: increase maximum kernel symbol length to 512

2022-09-28T06:56:25+00:00

Rust symbols can become quite long due to namespacing introduced
by modules, types, traits, generics, etc. For instance,
the following code:

    pub mod my_module {
        pub struct MyType;
        pub struct MyGenericType(T);

        pub trait MyTrait {
            fn my_method() -> u32;
        }

        impl MyTrait for MyGenericType {
            fn my_method() -> u32 {
                42
            }
        }
    }

generates a symbol of length 96 when using the upcoming v0 mangling scheme:

    _RNvXNtCshGpAVYOtgW1_7example9my_moduleINtB2_13MyGenericTypeNtB2_6MyTypeENtB2_7MyTrait9my_method

At the moment, Rust symbols may reach up to 300 in length.
Setting 512 as the maximum seems like a reasonable choice to
keep some headroom.

Reviewed-by: Kees Cook 
Reviewed-by: Petr Mladek 
Reviewed-by: Greg Kroah-Hartman 
Co-developed-by: Alex Gaynor 
Signed-off-by: Alex Gaynor 
Co-developed-by: Wedson Almeida Filho 
Signed-off-by: Wedson Almeida Filho 
Co-developed-by: Gary Guo 
Signed-off-by: Gary Guo 
Co-developed-by: Boqun Feng 
Signed-off-by: Boqun Feng 
Signed-off-by: Miguel Ojeda

kallsyms: Make kallsyms_on_each_symbol generally available

2022-05-10T21:42:06+00:00

Making kallsyms_on_each_symbol generally available, so it can be
used outside CONFIG_LIVEPATCH option in following changes.

Rather than adding another ifdef option let's make the function
generally available (when CONFIG_KALLSYMS option is defined).

Cc: Christoph Hellwig 
Reviewed-by: Masami Hiramatsu 
Signed-off-by: Jiri Olsa 
Link: https://lore.kernel.org/r/20220510122616.2652285-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov

asm-generic: Define CONFIG_HAVE_FUNCTION_DESCRIPTORS

2022-02-16T12:25:11+00:00

Replace HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR by a config option
named CONFIG_HAVE_FUNCTION_DESCRIPTORS and use it instead of
'dereference_function_descriptor' macro to know whether an
arch has function descriptors.

To limit churn in one of the following patches, use
an #ifdef/#else construct with empty first part
instead of an #ifndef in asm-generic/sections.h

On powerpc, make sure the config option matches the ABI used
by the compiler with a BUILD_BUG_ON() and add missing _CALL_ELF=2
when calling 'sparse' so that sparse sees the same piece of
code as GCC.

And include a helper to check whether an arch has function
descriptors or not : have_function_descriptors()

Signed-off-by: Christophe Leroy 
Reviewed-by: Kees Cook 
Reviewed-by: Nicholas Piggin 
Acked-by: Helge Deller 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/4a0f11fb0ea74a3197bc44dd7ba25e53a24fd03d.1644928018.git.christophe.leroy@csgroup.eu

sections: provide internal __is_kernel() and __is_kernel_text() helper

2021-11-09T18:02:51+00:00

An internal __is_kernel() helper which only check the kernel address
ranges, and an internal __is_kernel_text() helper which only check text
section ranges.

Link: https://lkml.kernel.org/r/20210930071143.63410-7-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Reviewed-by: Sergey Senozhatsky 
Cc: Alexander Potapenko 
Cc: Alexei Starovoitov 
Cc: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Borislav Petkov 
Cc: Christophe Leroy 
Cc: "David S. Miller" 
Cc: Dmitry Vyukov 
Cc: Ingo Molnar 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Paul Mackerras 
Cc: Petr Mladek 
Cc: Richard Henderson 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sections: move is_kernel_inittext() into sections.h

2021-11-09T18:02:50+00:00

The is_kernel_inittext() and init_kernel_text() are with same
functionality, let's just keep is_kernel_inittext() and move it into
sections.h, then update all the callers.

Link: https://lkml.kernel.org/r/20210930071143.63410-5-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Reviewed-by: Sergey Senozhatsky 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Arnd Bergmann 
Cc: Alexander Potapenko 
Cc: Alexei Starovoitov 
Cc: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Benjamin Herrenschmidt 
Cc: Borislav Petkov 
Cc: Christophe Leroy 
Cc: "David S. Miller" 
Cc: Dmitry Vyukov 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Paul Mackerras 
Cc: Petr Mladek 
Cc: Richard Henderson 
Cc: Steven Rostedt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kallsyms: fix address-checks for kernel related range

2021-11-09T18:02:50+00:00

The is_kernel_inittext/is_kernel_text/is_kernel function should not
include the end address(the labels _einittext, _etext and _end) when check
the address range, the issue exists since Linux v2.6.12.

Link: https://lkml.kernel.org/r/20210930071143.63410-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Reviewed-by: Petr Mladek 
Reviewed-by: Steven Rostedt (VMware) 
Acked-by: Sergey Senozhatsky 
Cc: Arnd Bergmann 
Cc: Alexander Potapenko 
Cc: Alexei Starovoitov 
Cc: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Benjamin Herrenschmidt 
Cc: Borislav Petkov 
Cc: Christophe Leroy 
Cc: "David S. Miller" 
Cc: Dmitry Vyukov 
Cc: Ingo Molnar 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Paul Mackerras 
Cc: Richard Henderson 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kallsyms: remove arch specific text and data check

2021-11-09T18:02:50+00:00

Patch series "sections: Unify kernel sections range check and use", v4.

There are three head files(kallsyms.h, kernel.h and sections.h) which
include the kernel sections range check, let's make some cleanup and unify
them.

1. cleanup arch specific text/data check and fix address boundary check
   in kallsyms.h

2. make all the basic/core kernel range check function into sections.h

3. update all the callers, and use the helper in sections.h to simplify
   the code

After this series, we have 5 APIs about kernel sections range check in
sections.h

 * is_kernel_rodata()		--- already in sections.h
 * is_kernel_core_data()	--- come from core_kernel_data() in kernel.h
 * is_kernel_inittext()		--- come from kernel.h and kallsyms.h
 * __is_kernel_text()		--- add new internal helper
 * __is_kernel()		--- add new internal helper

Note: For the last two helpers, people should not use directly, consider to
      use corresponding function in kallsyms.h.

This patch (of 11):

Remove arch specific text and data check after commit 4ba66a976072 ("arch:
remove blackfin port"), no need arch-specific text/data check.

Link: https://lkml.kernel.org/r/20210930071143.63410-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20210930071143.63410-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Reviewed-by: Sergey Senozhatsky 
Cc: Arnd Bergmann 
Cc: Steven Rostedt 
Cc: Ingo Molnar 
Cc: David S. Miller 
Cc: Alexei Starovoitov 
Cc: Andrey Ryabinin 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Christophe Leroy 
Cc: Kefeng Wang 
Cc: Alexander Potapenko 
Cc: Andrey Konovalov 
Cc: Borislav Petkov 
Cc: Dmitry Vyukov 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Michal Simek 
Cc: Petr Mladek 
Cc: Richard Henderson 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

module: add printk formats to add module build ID to stacktraces

2021-07-08T18:48:22+00:00

Let's make kernel stacktraces easier to identify by including the build
ID[1] of a module if the stacktrace is printing a symbol from a module.
This makes it simpler for developers to locate a kernel module's full
debuginfo for a particular stacktrace.  Combined with
scripts/decode_stracktrace.sh, a developer can download the matching
debuginfo from a debuginfod[2] server and find the exact file and line
number for the functions plus offsets in a stacktrace that match the
module.  This is especially useful for pstore crash debugging where the
kernel crashes are recorded in something like console-ramoops and the
recovery kernel/modules are different or the debuginfo doesn't exist on
the device due to space concerns (the debuginfo can be too large for space
limited devices).

Originally, I put this on the %pS format, but that was quickly rejected
given that %pS is used in other places such as ftrace where build IDs
aren't meaningful.  There was some discussions on the list to put every
module build ID into the "Modules linked in:" section of the stacktrace
message but that quickly becomes very hard to read once you have more than
three or four modules linked in.  It also provides too much information
when we don't expect each module to be traversed in a stacktrace.  Having
the build ID for modules that aren't important just makes things messy.
Splitting it to multiple lines for each module quickly explodes the number
of lines printed in an oops too, possibly wrapping the warning off the
console.  And finally, trying to stash away each module used in a
callstack to provide the ID of each symbol printed is cumbersome and would
require changes to each architecture to stash away modules and return
their build IDs once unwinding has completed.

Instead, we opt for the simpler approach of introducing new printk formats
'%pS[R]b' for "pointer symbolic backtrace with module build ID" and '%pBb'
for "pointer backtrace with module build ID" and then updating the few
places in the architecture layer where the stacktrace is printed to use
this new format.

Before:

 Call trace:
  lkdtm_WARNING+0x28/0x30 [lkdtm]
  direct_entry+0x16c/0x1b4 [lkdtm]
  full_proxy_write+0x74/0xa4
  vfs_write+0xec/0x2e8

After:

 Call trace:
  lkdtm_WARNING+0x28/0x30 [lkdtm 6c2215028606bda50de823490723dc4bc5bf46f9]
  direct_entry+0x16c/0x1b4 [lkdtm 6c2215028606bda50de823490723dc4bc5bf46f9]
  full_proxy_write+0x74/0xa4
  vfs_write+0xec/0x2e8

[akpm@linux-foundation.org: fix build with CONFIG_MODULES=n, tweak code layout]
[rdunlap@infradead.org: fix build when CONFIG_MODULES is not set]
  Link: https://lkml.kernel.org/r/20210513171510.20328-1-rdunlap@infradead.org
[akpm@linux-foundation.org: make kallsyms_lookup_buildid() static]
[cuibixuan@huawei.com: fix build error when CONFIG_SYSFS is disabled]
  Link: https://lkml.kernel.org/r/20210525105049.34804-1-cuibixuan@huawei.com

Link: https://lkml.kernel.org/r/20210511003845.2429846-6-swboyd@chromium.org
Link: https://fedoraproject.org/wiki/Releases/FeatureBuildId [1]
Link: https://sourceware.org/elfutils/Debuginfod.html [2]
Signed-off-by: Stephen Boyd 
Signed-off-by: Bixuan Cui 
Signed-off-by: Randy Dunlap 
Cc: Jiri Olsa 
Cc: Alexei Starovoitov 
Cc: Jessica Yu 
Cc: Evan Green 
Cc: Hsin-Yi Wang 
Cc: Petr Mladek 
Cc: Steven Rostedt 
Cc: Sergey Senozhatsky 
Cc: Andy Shevchenko 
Cc: Rasmus Villemoes 
Cc: Matthew Wilcox 
Cc: Baoquan He 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Dave Young 
Cc: Ingo Molnar 
Cc: Konstantin Khlebnikov 
Cc: Sasha Levin 
Cc: Thomas Gleixner 
Cc: Vivek Goyal 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kallsyms: only build {,module_}kallsyms_on_each_symbol when required

2021-02-08T11:24:04+00:00

kallsyms_on_each_symbol and module_kallsyms_on_each_symbol are only used
by the livepatching code, so don't build them if livepatching is not
enabled.

Reviewed-by: Miroslav Benes 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Jessica Yu

kallsyms: Refactor kallsyms_show_value() to take cred

2020-07-08T22:59:57+00:00

In order to perform future tests against the cred saved during open(),
switch kallsyms_show_value() to operate on a cred, and have all current
callers pass current_cred(). This makes it very obvious where callers
are checking the wrong credential in their "read" contexts. These will
be fixed in the coming patches.

Additionally switch return value to bool, since it is always used as a
direct permission check, not a 0-on-success, negative-on-error style
function return.

Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook