docs: fault-injection: add requirements of error injectable functions

Add a section about the requirements of the error injectable functions and
the type of errors.

Since this section must be read

docs: fault-injection: add requirements of error injectable functions

Add a section about the requirements of the error injectable functions and
the type of errors.

Since this section must be read before using ALLOW_ERROR_INJECTION()
macro, that section is referred from the comment of the macro too.

Link: https://lkml.kernel.org/r/167081321427.387937.15475445689482551048.stgit@devnote3
Link: https://lore.kernel.org/all/[email protected]/T/#u
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Florent Revest <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: KP Singh <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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error-injection: remove EI_ETYPE_NONE

Patch series "error-injection: Clarify the requirements of error
injectable functions".

Patches for clarifying the requirement of error injectable functions an

error-injection: remove EI_ETYPE_NONE

Patch series "error-injection: Clarify the requirements of error
injectable functions".

Patches for clarifying the requirement of error injectable functions and
to remove the confusing EI_ETYPE_NONE.


This patch (of 2):

Since the EI_ETYPE_NONE is confusing type, replace it with appropriate
errno. The EI_ETYPE_NONE has been introduced for a dummy (error) value,
but it can mislead people that they can use ALLOW_ERROR_INJECTION(func,
NONE). So remove it from the EI_ETYPE and use appropriate errno instead.

[[email protected]: include/linux/error-injection.h needs errno.h]
Link: https://lkml.kernel.org/r/167081319306.387937.10079195394503045678.stgit@devnote3
Link: https://lkml.kernel.org/r/167081320421.387937.4259807348852421112.stgit@devnote3
Fixes: 663faf9f7bee ("error-injection: Add injectable error types")
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Florent Revest <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: KP Singh <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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asm-generic/error-injection.h: fix a spelling mistake, and a coding style issue

Fix a spelling mistake "ganerating" -> "generating".
Remove trailing semicolon for a macro ALLOW_ERROR_INJECTION to fi

asm-generic/error-injection.h: fix a spelling mistake, and a coding style issue

Fix a spelling mistake "ganerating" -> "generating".
Remove trailing semicolon for a macro ALLOW_ERROR_INJECTION to fix a
coding style issue.

Signed-off-by: Wasin Thonkaew <[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>

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treewide: Convert macro and uses of __section(foo) to __section("foo")

Use a more generic form for __section that requires quotes to avoid
complications with clang and gcc differences.

Remove the q

treewide: Convert macro and uses of __section(foo) to __section("foo")

Use a more generic form for __section that requires quotes to avoid
complications with clang and gcc differences.

Remove the quote operator # from compiler_attributes.h __section macro.

Convert all unquoted __section(foo) uses to quoted __section("foo").
Also convert __attribute__((section("foo"))) uses to __section("foo")
even if the __attribute__ has multiple list entry forms.

Conversion done using the script at:

https://lore.kernel.org/lkml/[email protected]/2-convert_section.pl

Signed-off-by: Joe Perches <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
Reviewed-by: Miguel Ojeda <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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error-injection: Consolidate override function definition

The function override_function_with_return() is defined separately for
each architecture and every architecture's definition is almost same

error-injection: Consolidate override function definition

The function override_function_with_return() is defined separately for
each architecture and every architecture's definition is almost same
with each other. E.g. x86 and powerpc both define function in its own
asm/error-injection.h header and override_function_with_return() has
the same definition, the only difference is that x86 defines an extra
function just_return_func() but it is specific for x86 and is only used
by x86's override_function_with_return(), so don't need to export this
function.

This patch consolidates override_function_with_return() definition into
asm-generic/error-injection.h header, thus all architectures can use the
common definition. As result, the architecture specific headers are
removed; the include/linux/error-injection.h header also changes to
include asm-generic/error-injection.h header rather than architecture
header, furthermore, it includes linux/compiler.h for successful
compilation.

Reviewed-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Leo Yan <[email protected]>
Signed-off-by: Will Deacon <[email protected]>

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mm/page_alloc.c: allow error injection

Model call chain after should_failslab(). Likewise, we can now use a
kprobe to override the return value of should_fail_alloc_page() and inject
allocation fai

mm/page_alloc.c: allow error injection

Model call chain after should_failslab(). Likewise, we can now use a
kprobe to override the return value of should_fail_alloc_page() and inject
allocation failures into alloc_page*().

This will allow injecting allocation failures using the BCC tools even
without building kernel with CONFIG_FAIL_PAGE_ALLOC and booting it with a
fail_page_alloc= parameter, which incurs some overhead even when failures
are not being injected. On the other hand, this patch adds an
unconditional call to should_fail_alloc_page() from page allocation
hotpath. That overhead should be rather negligible with
CONFIG_FAIL_PAGE_ALLOC=n when there's no kprobe attached, though.

[[email protected]: changelog addition]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Benjamin Poirier <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Alexander Duyck <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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error-injection: Add injectable error types

Add injectable error types for each error-injectable function.

One motivation of error injection test is to find software flaws,
mistakes or mis-handling

error-injection: Add injectable error types

Add injectable error types for each error-injectable function.

One motivation of error injection test is to find software flaws,
mistakes or mis-handlings of expectable errors. If we find such
flaws by the test, that is a program bug, so we need to fix it.

But if the tester miss input the error (e.g. just return success
code without processing anything), it causes unexpected behavior
even if the caller is correctly programmed to handle any errors.
That is not what we want to test by error injection.

To clarify what type of errors the caller must expect for each
injectable function, this introduces injectable error types:

- EI_ETYPE_NULL : means the function will return NULL if it
fails. No ERR_PTR, just a NULL.
- EI_ETYPE_ERRNO : means the function will return -ERRNO
if it fails.
- EI_ETYPE_ERRNO_NULL : means the function will return -ERRNO
(ERR_PTR) or NULL.

ALLOW_ERROR_INJECTION() macro is expanded to get one of
NULL, ERRNO, ERRNO_NULL to record the error type for
each function. e.g.

ALLOW_ERROR_INJECTION(open_ctree, ERRNO)

This error types are shown in debugfs as below.

====
/ # cat /sys/kernel/debug/error_injection/list
open_ctree [btrfs] ERRNO
io_ctl_init [btrfs] ERRNO
====

Signed-off-by: Masami Hiramatsu <[email protected]>
Reviewed-by: Josef Bacik <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>

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error-injection: Separate error-injection from kprobe

Since error-injection framework is not limited to be used
by kprobes, nor bpf. Other kernel subsystems can use it
freely for checking safeness o

error-injection: Separate error-injection from kprobe

Since error-injection framework is not limited to be used
by kprobes, nor bpf. Other kernel subsystems can use it
freely for checking safeness of error-injection, e.g.
livepatch, ftrace etc.
So this separate error-injection framework from kprobes.

Some differences has been made:

- "kprobe" word is removed from any APIs/structures.
- BPF_ALLOW_ERROR_INJECTION() is renamed to
ALLOW_ERROR_INJECTION() since it is not limited for BPF too.
- CONFIG_FUNCTION_ERROR_INJECTION is the config item of this
feature. It is automatically enabled if the arch supports
error injection feature for kprobe or ftrace etc.

Signed-off-by: Masami Hiramatsu <[email protected]>
Reviewed-by: Josef Bacik <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>

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