bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 82 insertions, 0 deletions

diff --git a/Documentation/fb/s3fb.rst b/Documentation/fb/s3fb.rst
new file mode 100644
index 000000000..e809d69c2
--- /dev/null
+++ b/Documentation/fb/s3fb.rst
@@ -0,0 +1,82 @@
+===========================================
+s3fb - fbdev driver for S3 Trio/Virge chips
+===========================================
+
+
+Supported Hardware
+==================
+
+	S3 Trio32
+	S3 Trio64 (and variants V+, UV+, V2/DX, V2/GX)
+	S3 Virge  (and variants VX, DX, GX and GX2+)
+	S3 Plato/PX		(completely untested)
+	S3 Aurora64V+		(completely untested)
+
+	- only PCI bus supported
+	- only BIOS initialized VGA devices supported
+	- probably not working on big endian
+
+I tested s3fb on Trio64 (plain, V+ and V2/DX) and Virge (plain, VX, DX),
+all on i386.
+
+
+Supported Features
+==================
+
+	*  4 bpp pseudocolor modes (with 18bit palette, two variants)
+	*  8 bpp pseudocolor mode (with 18bit palette)
+	* 16 bpp truecolor modes (RGB 555 and RGB 565)
+	* 24 bpp truecolor mode (RGB 888) on (only on Virge VX)
+	* 32 bpp truecolor mode (RGB 888) on (not on Virge VX)
+	* text mode (activated by bpp = 0)
+	* interlaced mode variant (not available in text mode)
+	* doublescan mode variant (not available in text mode)
+	* panning in both directions
+	* suspend/resume support
+	* DPMS support
+
+Text mode is supported even in higher resolutions, but there is limitation to
+lower pixclocks (maximum usually between 50-60 MHz, depending on specific
+hardware, i get best results from plain S3 Trio32 card - about 75 MHz). This
+limitation is not enforced by driver. Text mode supports 8bit wide fonts only
+(hardware limitation) and 16bit tall fonts (driver limitation). Text mode
+support is broken on S3 Trio64 V2/DX.
+
+There are two 4 bpp modes. First mode (selected if nonstd == 0) is mode with
+packed pixels, high nibble first. Second mode (selected if nonstd == 1) is mode
+with interleaved planes (1 byte interleave), MSB first. Both modes support
+8bit wide fonts only (driver limitation).
+
+Suspend/resume works on systems that initialize video card during resume and
+if device is active (for example used by fbcon).
+
+
+Missing Features
+================
+(alias TODO list)
+
+	* secondary (not initialized by BIOS) device support
+	* big endian support
+	* Zorro bus support
+	* MMIO support
+	* 24 bpp mode support on more cards
+	* support for fontwidths != 8 in 4 bpp modes
+	* support for fontheight != 16 in text mode
+	* composite and external sync (is anyone able to test this?)
+	* hardware cursor
+	* video overlay support
+	* vsync synchronization
+	* feature connector support
+	* acceleration support (8514-like 2D, Virge 3D, busmaster transfers)
+	* better values for some magic registers (performance issues)
+
+
+Known bugs
+==========
+
+	* cursor disable in text mode doesn't work
+	* text mode broken on S3 Trio64 V2/DX
+
+
+--
+Ondrej Zajicek <santiago@crfreenet.org>