selftests/bpf: Check that JMP32 pointer vs zero jumps are not predictedgrafted

Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which
the verifier used to skip, contains an out of bounds map value access,
hence w/o the previous patch the program is accepted. See previous patch
for detailed description.

Reported-by: Nicholas Carlini <npc@anthropic.com>
Suggested-by: Nicholas Carlini <npc@anthropic.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/Documentation/admin-guide/device-mapper/dm-ebs.rst b/Documentation/admin-guide/device-mapper/dm-ebs.rst
new file mode 100644
index 000000000..c09f66db5
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-ebs.rst
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+======
+dm-ebs
+======
+
+
+This target is similar to the linear target except that it emulates
+a smaller logical block size on a device with a larger logical block
+size.  Its main purpose is to provide emulation of 512 byte sectors on
+devices that do not provide this emulation (i.e. 4K native disks).
+
+Supported emulated logical block sizes 512, 1024, 2048 and 4096.
+
+Underlying block size can be set to > 4K to test buffering larger units.
+
+
+Table parameters
+----------------
+  <dev path> <offset> <emulated sectors> [<underlying sectors>]
+
+Mandatory parameters:
+
+    <dev path>:
+        Full pathname to the underlying block-device,
+        or a "major:minor" device-number.
+    <offset>:
+        Starting sector within the device;
+        has to be a multiple of <emulated sectors>.
+    <emulated sectors>:
+        Number of sectors defining the logical block size to be emulated;
+        1, 2, 4, 8 sectors of 512 bytes supported.
+
+Optional parameter:
+
+    <underlying sectors>:
+        Number of sectors defining the logical block size of <dev path>.
+        2^N supported, e.g. 8 = emulate 8 sectors of 512 bytes = 4KiB.
+        If not provided, the logical block size of <dev path> will be used.
+
+
+Examples:
+
+Emulate 1 sector = 512 bytes logical block size on /dev/sda starting at
+offset 1024 sectors with underlying devices block size automatically set:
+
+ebs /dev/sda 1024 1
+
+Emulate 2 sector = 1KiB logical block size on /dev/sda starting at
+offset 128 sectors, enforce 2KiB underlying device block size.
+This presumes 2KiB logical blocksize on /dev/sda or less to work:
+
+ebs /dev/sda 128 2 4