objtool: Validate disassembler headers in libopcodes probegrafted

commit 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
tested for libopcodes availability by linking a test snippet with a forward
declaration of disassemble_init_for_target().

However, testing symbol linkage with an extern declaration only verifies
the presence of the library (.so/.a) and bypasses checking for development
headers (binutils-dev). On systems where libopcodes is present without
development headers installed, the probe succeeds, enabling BUILD_DISAS.
Subsequent compilation of objtool then fails:

  fatal error: 'bfd.h' file not found
    113 | #include <bfd.h>

Additionally, the probe invokes $(HOSTCC) without $(HOSTCFLAGS), ignoring
any sysroot or include flags specified for the host compiler.

Fix this by including <bfd.h> and <dis-asm.h> directly in the test snippet,
passing $(HOSTCFLAGS) so host compiler options are respected, and defining
PACKAGE="objtool" to satisfy the configuration check in <bfd.h>.

Fixes: 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
Fixes: 436326bc525d ("objtool: fix build failure due to missing libopcodes check")
Reported-by: Alice Ryhl <aliceryhl@google.com>
Assisted-by: Antigravity:Gemini-Next
Signed-off-by: Ulises Mendez Martinez <umendez@google.com>
Link: https://patch.msgid.link/20260904150710.2997558-1-umendez@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

1 files changed, 186 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-backlight b/Documentation/ABI/testing/sysfs-class-backlight
new file mode 100644
index 000000000..c453646b0
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-backlight
@@ -0,0 +1,186 @@
+What:		/sys/class/backlight/<backlight>/scale
+Date:		July 2019
+KernelVersion:	5.4
+Contact:	Daniel Thompson <daniel.thompson@linaro.org>
+Description:
+		Description of the scale of the brightness curve.
+
+		The human eye senses brightness approximately logarithmically,
+		hence linear changes in brightness are perceived as being
+		non-linear. To achieve a linear perception of brightness changes
+		controls like sliders need to apply a logarithmic mapping for
+		backlights with a linear brightness curve.
+
+		Possible values of the attribute are:
+
+		unknown
+		  The scale of the brightness curve is unknown.
+
+		linear
+		  The brightness changes linearly with each step. Brightness
+		  controls should apply a logarithmic mapping for a linear
+		  perception.
+
+		non-linear
+		  The brightness changes non-linearly with each step. Brightness
+		  controls should use a linear mapping for a linear perception.
+
+What:		/sys/class/backlight/<backlight>/ambient_light_level
+Date:		Apr, 2010
+KernelVersion:	v2.6.35
+Contact:	Michael Hennerich <michael.hennerich@analog.com>
+Description:
+		(RO) Get conversion value of the light sensor.
+
+		The value is automatically updated every 80 ms when the
+		light sensor is enabled.
+
+		The value range is device-driver specific:
+
+		For ADP8870:
+
+		  It returns integer between 0 (dark) and 8000 (max ambient
+		  brightness).
+
+		For ADP8860:
+
+		  It returns a 13-bits integer.
+
+What:		/sys/class/backlight/<backlight>/ambient_light_zone
+Date:		Apr, 2010
+KernelVersion:	v2.6.35
+Contact:	Michael Hennerich <michael.hennerich@analog.com>,
+		device-drivers-devel@blackfin.uclinux.org
+
+Description:
+		(RW) Read or write the specific brightness level at which the
+		backlight operates.
+
+		The value meaning is device-driver specific:
+
+		For ADP8860:
+
+		  ==	==========================
+		   0	Off: Backlight set to 0 mA
+		   1	Level 1: daylight
+		   2	Level 2: bright
+		   3	Level 3: dark
+		  ==	==========================
+
+		For ADP8870:
+
+		  ==	==========================
+		   0	Off: Backlight set to 0 mA
+		   1	Level 1: daylight
+		   2	Level 2: bright
+		   3	Level 3: office
+		   4	Level 4: indoor
+		   5	Level 5: dark
+		  ==	==========================
+
+		Writing 0 returns to normal/automatic ambient light level
+		operation.
+
+		It can be enabled by writing the value stored in
+		/sys/class/backlight/<backlight>/max_brightness to
+		/sys/class/backlight/<backlight>/brightness.
+
+What:		/sys/class/backlight/<backlight>/<ambient light zone>_max
+Date:		Sep, 2009
+KernelVersion:	v2.6.32
+Contact:	device-drivers-devel@blackfin.uclinux.org
+Description:
+		Control the maximum brightness for <ambient light zone>
+		on this <backlight>. Values are between 0 and 127. This file
+		will also show the brightness level stored for this
+		<ambient light zone>.
+
+		The <ambient light zone> is device-driver specific:
+
+		For ADP5520 and ADP5501, <ambient light zone> can be:
+
+		===========  ================================================
+		Ambient      sysfs entry
+		light zone
+		===========  ================================================
+		daylight     /sys/class/backlight/<backlight>/daylight_max
+		office       /sys/class/backlight/<backlight>/office_max
+		dark         /sys/class/backlight/<backlight>/dark_max
+		===========  ================================================
+
+		For ADP8860, <ambient light zone> can be:
+
+		===========  ================================================
+		Ambient      sysfs entry
+		light zone
+		===========  ================================================
+		l1_daylight  /sys/class/backlight/<backlight>/l1_daylight_max
+		l2_office    /sys/class/backlight/<backlight>/l2_office_max
+		l3_dark      /sys/class/backlight/<backlight>/l3_dark_max
+		===========  ================================================
+
+		For ADP8870, <ambient light zone> can be:
+
+		===========  ================================================
+		Ambient      sysfs entry
+		light zone
+		===========  ================================================
+		l1_daylight  /sys/class/backlight/<backlight>/l1_daylight_max
+		l2_bright    /sys/class/backlight/<backlight>/l2_bright_max
+		l3_office    /sys/class/backlight/<backlight>/l3_office_max
+		l4_indoor    /sys/class/backlight/<backlight>/l4_indoor_max
+		l5_dark      /sys/class/backlight/<backlight>/l5_dark_max
+		===========  ================================================
+
+		See also: /sys/class/backlight/<backlight>/ambient_light_zone.
+
+What:		/sys/class/backlight/<backlight>/<ambient light zone>_dim
+Date:		Sep, 2009
+KernelVersion:	v2.6.32
+Contact:	device-drivers-devel@blackfin.uclinux.org
+Description:
+		Control the dim brightness for <ambient light zone>
+		on this <backlight>. Values are between 0 and 127, typically
+		set to 0. Full off when the backlight is disabled.
+		This file will also show the dim brightness level stored for
+		this <ambient light zone>.
+
+		The <ambient light zone> is device-driver specific:
+
+		For ADP5520 and ADP5501, <ambient light zone> can be:
+
+		===========  ================================================
+		Ambient      sysfs entry
+		light zone
+		===========  ================================================
+		daylight     /sys/class/backlight/<backlight>/daylight_dim
+		office       /sys/class/backlight/<backlight>/office_dim
+		dark         /sys/class/backlight/<backlight>/dark_dim
+		===========  ================================================
+
+		For ADP8860, <ambient light zone> can be:
+
+		===========  ================================================
+		Ambient      sysfs entry
+		light zone
+		===========  ================================================
+		l1_daylight  /sys/class/backlight/<backlight>/l1_daylight_dim
+		l2_office    /sys/class/backlight/<backlight>/l2_office_dim
+		l3_dark      /sys/class/backlight/<backlight>/l3_dark_dim
+		===========  ================================================
+
+		For ADP8870, <ambient light zone> can be:
+
+		===========  ================================================
+		Ambient      sysfs entry
+		light zone
+		===========  ================================================
+		l1_daylight  /sys/class/backlight/<backlight>/l1_daylight_dim
+		l2_bright    /sys/class/backlight/<backlight>/l2_bright_dim
+		l3_office    /sys/class/backlight/<backlight>/l3_office_dim
+		l4_indoor    /sys/class/backlight/<backlight>/l4_indoor_dim
+		l5_dark      /sys/class/backlight/<backlight>/l5_dark_dim
+		===========  ================================================
+
+		See also: /sys/class/backlight/<backlight>/ambient_light_zone.
+