Merge branch 'next' into for-linus

Prepare input updates for 6.18 merge window.

54 files changed, 2920 insertions, 2007 deletions

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index a6461ea411f7..d0ee33a487be 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -309,13 +309,15 @@ $(obj)/%.lst: $(obj)/%.c FORCE
 # The features in this list are the ones allowed for non-`rust/` code.
 #
 #   - Stable since Rust 1.81.0: `feature(lint_reasons)`.
-#   - Stable since Rust 1.82.0: `feature(asm_const)`, `feature(raw_ref_op)`.
+#   - Stable since Rust 1.82.0: `feature(asm_const)`,
+#     `feature(offset_of_nested)`, `feature(raw_ref_op)`.
 #   - Stable since Rust 1.87.0: `feature(asm_goto)`.
 #   - Expected to become stable: `feature(arbitrary_self_types)`.
+#   - To be determined: `feature(used_with_arg)`.
 #
 # Please see https://github.com/Rust-for-Linux/linux/issues/2 for details on
 # the unstable features in use.
-rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op
+rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,offset_of_nested,raw_ref_op,used_with_arg
 
 # `--out-dir` is required to avoid temporaries being created by `rustc` in the
 # current working directory, which may be not accessible in the out-of-tree
diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index 435ab3f0ec44..b0e1423b09c2 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -8,20 +8,6 @@ ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
 endif
 export DISABLE_LATENT_ENTROPY_PLUGIN
 
-gcc-plugin-$(CONFIG_GCC_PLUGIN_STACKLEAK)	+= stackleak_plugin.so
-gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK)		\
-		+= -DSTACKLEAK_PLUGIN
-gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK)		\
-		+= -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_STACKLEAK_TRACK_MIN_SIZE)
-gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK)		\
-		+= -fplugin-arg-stackleak_plugin-arch=$(SRCARCH)
-gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK_VERBOSE)	\
-		+= -fplugin-arg-stackleak_plugin-verbose
-ifdef CONFIG_GCC_PLUGIN_STACKLEAK
-    DISABLE_STACKLEAK_PLUGIN += -fplugin-arg-stackleak_plugin-disable
-endif
-export DISABLE_STACKLEAK_PLUGIN
-
 # All the plugin CFLAGS are collected here in case a build target needs to
 # filter them out of the KBUILD_CFLAGS.
 GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y)) -DGCC_PLUGINS
@@ -34,6 +20,8 @@ KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
 # be included in GCC_PLUGIN so they can get built.
 gcc-plugin-external-$(CONFIG_GCC_PLUGIN_RANDSTRUCT)		\
 	+= randomize_layout_plugin.so
+gcc-plugin-external-$(CONFIG_GCC_PLUGIN_STACKLEAK)		\
+	+= stackleak_plugin.so
 
 # All enabled GCC plugins are collected here for building in
 # scripts/gcc-scripts/Makefile.
diff --git a/scripts/Makefile.kstack_erase b/scripts/Makefile.kstack_erase
new file mode 100644
index 000000000000..ee7e4ef7b892
--- /dev/null
+++ b/scripts/Makefile.kstack_erase
@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-2.0
+
+ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+kstack-erase-cflags-y += -fplugin=$(objtree)/scripts/gcc-plugins/stackleak_plugin.so
+kstack-erase-cflags-y += -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE)
+kstack-erase-cflags-y += -fplugin-arg-stackleak_plugin-arch=$(SRCARCH)
+kstack-erase-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK_VERBOSE) += -fplugin-arg-stackleak_plugin-verbose
+DISABLE_KSTACK_ERASE := -fplugin-arg-stackleak_plugin-disable
+endif
+
+ifdef CONFIG_CC_IS_CLANG
+kstack-erase-cflags-y += -fsanitize-coverage=stack-depth
+kstack-erase-cflags-y += -fsanitize-coverage-stack-depth-callback-min=$(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE)
+DISABLE_KSTACK_ERASE  := -fno-sanitize-coverage=stack-depth
+endif
+
+KSTACK_ERASE_CFLAGS   := $(kstack-erase-cflags-y)
+
+export KSTACK_ERASE_CFLAGS DISABLE_KSTACK_ERASE
+
+KBUILD_CFLAGS += $(KSTACK_ERASE_CFLAGS)
diff --git a/scripts/check-sysctl-docs b/scripts/check-sysctl-docs
index 20274c63e745..910fd8a9a268 100755
--- a/scripts/check-sysctl-docs
+++ b/scripts/check-sysctl-docs
@@ -1,4 +1,4 @@
-#!/usr/bin/gawk -f
+#!/usr/bin/env -S gawk -f
 # SPDX-License-Identifier: GPL-2.0
 
 # Script to check sysctl documentation against source files
@@ -13,10 +13,22 @@
 # Specify -vdebug=1 to see debugging information
 
 BEGIN {
-    if (!table) {
+	if (!table) {
 	print "Please specify the table to look for using the table variable" > "/dev/stderr"
 	exit 1
-    }
+	}
+
+	# Documentation title skiplist
+	skiplist[0] = "^Documentation for"
+	skiplist[1] = "Network core options$"
+	skiplist[2] = "POSIX message queues filesystem$"
+	skiplist[3] = "Configuration options"
+	skiplist[4] = ". /proc/sys/fs"
+	skiplist[5] = "^Introduction$"
+	skiplist[6] = "^seccomp$"
+	skiplist[7] = "^pty$"
+	skiplist[8] = "^firmware_config$"
+	skiplist[9] = "^random$"
 }
 
 # The following globals are used:
@@ -31,124 +43,132 @@ BEGIN {
 
 # Remove punctuation from the given value
 function trimpunct(value) {
-    while (value ~ /^["&]/) {
-	value = substr(value, 2)
-    }
-    while (value ~ /[]["&,}]$/) {
-	value = substr(value, 1, length(value) - 1)
-    }
-    return value
+	while (value ~ /^["&]/) {
+		value = substr(value, 2)
+	}
+	while (value ~ /[]["&,}]$/) {
+		value = substr(value, 1, length(value) - 1)
+	}
+	return value
 }
 
 # Print the information for the given entry
 function printentry(entry) {
-    seen[entry]++
-    printf "* %s from %s", entry, file[entry]
-    if (documented[entry]) {
-	printf " (documented)"
-    }
-    print ""
+	seen[entry]++
+	printf "* %s from %s", entry, file[entry]
+	if (documented[entry]) {
+		printf " (documented)"
+	}
+	print ""
 }
 
 
 # Stage 1: build the list of documented entries
 FNR == NR && /^=+$/ {
-    if (prevline ~ /Documentation for/) {
-	# This is the main title
-	next
-    }
-
-    # The previous line is a section title, parse it
-    $0 = prevline
-    if (debug) print "Parsing " $0
-    inbrackets = 0
-    for (i = 1; i <= NF; i++) {
-	if (length($i) == 0) {
-	    continue
-	}
-	if (!inbrackets && substr($i, 1, 1) == "(") {
-	    inbrackets = 1
-	}
-	if (!inbrackets) {
-	    token = trimpunct($i)
-	    if (length(token) > 0 && token != "and") {
-		if (debug) print trimpunct($i)
-		documented[trimpunct($i)]++
-	    }
+	for (i in skiplist) {
+		if (prevline ~ skiplist[i]) {
+			next
+		}
 	}
-	if (inbrackets && substr($i, length($i), 1) == ")") {
-	    inbrackets = 0
+
+	# The previous line is a section title, parse it
+	$0 = prevline
+	if (debug) print "Parsing " $0
+	inbrackets = 0
+	for (i = 1; i <= NF; i++) {
+		if (length($i) == 0) {
+			continue
+		}
+		if (!inbrackets && substr($i, 1, 1) == "(") {
+			inbrackets = 1
+		}
+		if (!inbrackets) {
+			token = trimpunct($i)
+			if (length(token) > 0 && token != "and") {
+				if (debug) print trimpunct($i)
+					documented[trimpunct($i)]++
+			}
+		}
+		if (inbrackets && substr($i, length($i), 1) == ")") {
+			inbrackets = 0
+		}
 	}
-    }
 }
 
 FNR == NR {
-    prevline = $0
-    next
+	prevline = $0
+	next
 }
 
 
 # Stage 2: process each file and find all sysctl tables
 BEGINFILE {
-    delete entries
-    curtable = ""
-    curentry = ""
-    delete vars
-    if (debug) print "Processing file " FILENAME
+	delete entries
+	curtable = ""
+	curentry = ""
+	delete vars
+	if (debug) print "Processing file " FILENAME
 }
 
 /^static( const)? struct ctl_table/ {
-    match($0, /static( const)? struct ctl_table ([^][]+)/, tables)
-    curtable = tables[2]
-    if (debug) print "Processing table " curtable
+	match($0, /static( const)? struct ctl_table ([^][]+)/, tables)
+	curtable = tables[2]
+	if (debug) print "Processing table " curtable
 }
 
 /^};$/ {
-    curtable = ""
-    curentry = ""
-    delete vars
+	curtable = ""
+	curentry = ""
+	delete vars
 }
 
 curtable && /\.procname[\t ]*=[\t ]*".+"/ {
-    match($0, /.procname[\t ]*=[\t ]*"([^"]+)"/, names)
-    curentry = names[1]
-    if (debug) print "Adding entry " curentry " to table " curtable
-    entries[curtable][curentry]++
-    file[curentry] = FILENAME
+	match($0, /.procname[\t ]*=[\t ]*"([^"]+)"/, names)
+	curentry = names[1]
+	if (debug) print "Adding entry " curentry " to table " curtable
+	entries[curtable][curentry]++
+	file[curentry] = FILENAME
+}
+
+curtable && /UCOUNT_ENTRY.*/ {
+	match($0, /UCOUNT_ENTRY\("([^"]+)"\)/, names)
+	curentry = names[1]
+	if (debug) print "Adding entry " curentry " to table " curtable
+	entries[curtable][curentry]++
+	file[curentry] = FILENAME
 }
 
 /register_sysctl.*/ {
-    match($0, /register_sysctl(|_init|_sz)\("([^"]+)" *, *([^,)]+)/, tables)
-    if (debug) print "Registering table " tables[3] " at " tables[2]
-    if (tables[2] == table) {
-        for (entry in entries[tables[3]]) {
-            printentry(entry)
-        }
-    }
+	match($0, /register_sysctl(|_init|_sz)\("([^"]+)" *, *([^,)]+)/, tables)
+	if (debug) print "Registering table " tables[3] " at " tables[2]
+	if (tables[2] == table) {
+		for (entry in entries[tables[3]]) {
+			printentry(entry)
+		}
+	}
 }
 
 /kmemdup.*/ {
-    match($0, /([^ \t]+) *= *kmemdup\(([^,]+) *,/, names)
-    if (debug) print "Found variable " names[1] " for table " names[2]
-    if (names[2] in entries) {
-        vars[names[1]] = names[2]
-    }
+	match($0, /([^ \t]+) *= *kmemdup\(([^,]+) *,/, names)
+	if (debug) print "Found variable " names[1] " for table " names[2]
+	if (names[2] in entries) {
+		vars[names[1]] = names[2]
+	}
 }
 
 /__register_sysctl_table.*/ {
-    match($0, /__register_sysctl_table\([^,]+, *"([^"]+)" *, *([^,]+)/, tables)
-    if (debug) print "Registering variable table " tables[2] " at " tables[1]
-    if (tables[1] == table && tables[2] in vars) {
-        for (entry in entries[vars[tables[2]]]) {
-            printentry(entry)
-        }
-    }
+	match($0, /__register_sysctl_table\([^,]+, *"([^"]+)" *, *([^,]+)/, tables)
+	if (debug) print "Registering variable table " tables[2] " at " tables[1]
+	if (tables[1] == table && tables[2] in vars) {
+		for (entry in entries[vars[tables[2]]]) {
+			printentry(entry)
+		}
+	}
 }
 
 END {
-    for (entry in documented) {
-	if (!seen[entry]) {
-	    print "No implementation for " entry
+	for (entry in documented) {
+		if (!seen[entry])
+			print "No implementation for " entry
 	}
-    }
 }
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 664f7b7a622c..e722dd6fa8ef 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -685,6 +685,9 @@ our $tracing_logging_tags = qr{(?xi:
 	[\.\!:\s]*
 )};
 
+# Device ID types like found in include/linux/mod_devicetable.h.
+our $dev_id_types = qr{\b[a-z]\w*_device_id\b};
+
 sub edit_distance_min {
 	my (@arr) = @_;
 	my $len = scalar @arr;
@@ -857,8 +860,6 @@ our %deprecated_apis = (
 	"kunmap"				=> "kunmap_local",
 	"kmap_atomic"				=> "kmap_local_page",
 	"kunmap_atomic"				=> "kunmap_local",
-	"srcu_read_lock_lite"			=> "srcu_read_lock_fast",
-	"srcu_read_unlock_lite"			=> "srcu_read_unlock_fast",
 );
 
 #Create a search pattern for all these strings to speed up a loop below
@@ -3502,9 +3503,10 @@ sub process {
 # Check for various typo / spelling mistakes
 		if (defined($misspellings) &&
 		    ($in_commit_log || $line =~ /^(?:\+|Subject:)/i)) {
-			while ($rawline =~ /(?:^|[^\w\-'`])($misspellings)(?:[^\w\-'`]|$)/gi) {
+			my $rawline_utf8 = decode("utf8", $rawline);
+			while ($rawline_utf8 =~ /(?:^|[^\w\-'`])($misspellings)(?:[^\w\-'`]|$)/gi) {
 				my $typo = $1;
-				my $blank = copy_spacing($rawline);
+				my $blank = copy_spacing($rawline_utf8);
 				my $ptr = substr($blank, 0, $-[1]) . "^" x length($typo);
 				my $hereptr = "$hereline$ptr\n";
 				my $typo_fix = $spelling_fix{lc($typo)};
@@ -3741,6 +3743,18 @@ sub process {
 			}
 		}
 
+# Check for RGMII phy-mode with delay on PCB
+		if ($realfile =~ /\.(dts|dtsi|dtso)$/ &&
+		    $line =~ /^\+\s*(phy-mode|phy-connection-type)\s*=\s*"/ &&
+		    !ctx_has_comment($first_line, $linenr)) {
+			my $prop = $1;
+			my $mode = get_quoted_string($line, $rawline);
+			if ($mode =~ /^"rgmii(?:|-rxid|-txid)"$/) {
+				WARN("UNCOMMENTED_RGMII_MODE",
+				     "$prop $mode without comment -- delays on the PCB should be described, otherwise use \"rgmii-id\"\n" . $herecurr);
+			}
+		}
+
 # check for using SPDX license tag at beginning of files
 		if ($realline == $checklicenseline) {
 			if ($rawline =~ /^[ \+]\s*\#\!\s*\//) {
@@ -7678,6 +7692,31 @@ sub process {
 			WARN("DUPLICATED_SYSCTL_CONST",
 				"duplicated sysctl range checking value '$1', consider using the shared one in include/linux/sysctl.h\n" . $herecurr);
 		}
+
+# Check that *_device_id tables have sentinel entries.
+		if (defined $stat && $line =~ /struct\s+$dev_id_types\s+\w+\s*\[\s*\]\s*=\s*\{/) {
+			my $stripped = $stat;
+
+			# Strip diff line prefixes.
+			$stripped =~ s/(^|\n)./$1/g;
+			# Line continuations.
+			$stripped =~ s/\\\n/\n/g;
+			# Strip whitespace, empty strings, zeroes, and commas.
+			$stripped =~ s/""//g;
+			$stripped =~ s/0x0//g;
+			$stripped =~ s/[\s$;,0]//g;
+			# Strip field assignments.
+			$stripped =~ s/\.$Ident=//g;
+
+			if (!(substr($stripped, -4) eq "{}};" ||
+			      substr($stripped, -6) eq "{{}}};" ||
+			      $stripped =~ /ISAPNP_DEVICE_SINGLE_END}};$/ ||
+			      $stripped =~ /ISAPNP_CARD_END}};$/ ||
+			      $stripped =~ /NULL};$/ ||
+			      $stripped =~ /PCMCIA_DEVICE_NULL};$/)) {
+				ERROR("MISSING_SENTINEL", "missing sentinel in ID array\n" . "$here\n$stat\n");
+			}
+		}
 	}
 
 	# If we have no input at all, then there is nothing to report on
diff --git a/scripts/checktransupdate.py b/scripts/checktransupdate.py
index 578c3fecfdfd..e39529e46c3d 100755
--- a/scripts/checktransupdate.py
+++ b/scripts/checktransupdate.py
@@ -24,6 +24,7 @@ commit 42fb9cfd5b18 ("Documentation: dev-tools: Add link to RV docs")
 """
 
 import os
+import re
 import time
 import logging
 from argparse import ArgumentParser, ArgumentTypeError, BooleanOptionalAction
@@ -69,6 +70,38 @@ def get_origin_from_trans(origin_path, t_from_head):
     return o_from_t
 
 
+def get_origin_from_trans_smartly(origin_path, t_from_head):
+    """Get the latest origin commit from the formatted translation commit:
+    (1) update to commit HASH (TITLE)
+    (2) Update the translation through commit HASH (TITLE)
+    """
+    # catch flag for 12-bit commit hash
+    HASH = r'([0-9a-f]{12})'
+    # pattern 1: contains "update to commit HASH"
+    pat_update_to = re.compile(rf'update to commit {HASH}')
+    # pattern 2: contains "Update the translation through commit HASH"
+    pat_update_translation = re.compile(rf'Update the translation through commit {HASH}')
+
+    origin_commit_hash = None
+    for line in t_from_head["message"]:
+        # check if the line matches the first pattern
+        match = pat_update_to.search(line)
+        if match:
+            origin_commit_hash = match.group(1)
+            break
+        # check if the line matches the second pattern
+        match = pat_update_translation.search(line)
+        if match:
+            origin_commit_hash = match.group(1)
+            break
+    if origin_commit_hash is None:
+        return None
+    o_from_t = get_latest_commit_from(origin_path, origin_commit_hash)
+    if o_from_t is not None:
+        logging.debug("tracked origin commit id: %s", o_from_t["hash"])
+    return o_from_t
+
+
 def get_commits_count_between(opath, commit1, commit2):
     """Get the commits count between two commits for the specified file"""
     command = f"git log --pretty=format:%H {commit1}...{commit2} -- {opath}"
@@ -108,7 +141,10 @@ def check_per_file(file_path):
         logging.error("Cannot find the latest commit for %s", file_path)
         return
 
-    o_from_t = get_origin_from_trans(opath, t_from_head)
+    o_from_t = get_origin_from_trans_smartly(opath, t_from_head)
+    # notice, o_from_t from get_*_smartly() is always more accurate than from get_*()
+    if o_from_t is None:
+        o_from_t = get_origin_from_trans(opath, t_from_head)
 
     if o_from_t is None:
         logging.error("Error: Cannot find the latest origin commit for %s", file_path)
diff --git a/scripts/coccinelle/misc/secs_to_jiffies.cocci b/scripts/coccinelle/misc/secs_to_jiffies.cocci
index 416f348174ca..f3241ce75a7b 100644
--- a/scripts/coccinelle/misc/secs_to_jiffies.cocci
+++ b/scripts/coccinelle/misc/secs_to_jiffies.cocci
@@ -7,26 +7,65 @@
 // Confidence: High
 // Copyright: (C) 2024 Easwar Hariharan, Microsoft
 // Keywords: secs, seconds, jiffies
-//
+// Options: --include-headers
 
 virtual patch
+virtual report
+virtual context
 
-@depends on patch@ constant C; @@
+@pconst depends on patch@ constant C; @@
 
 - msecs_to_jiffies(C * 1000)
 + secs_to_jiffies(C)
 
-@depends on patch@ constant C; @@
+@pconstms depends on patch@ constant C; @@
 
 - msecs_to_jiffies(C * MSEC_PER_SEC)
 + secs_to_jiffies(C)
 
-@depends on patch@ expression E; @@
+@pexpr depends on patch@ expression E; @@
 
 - msecs_to_jiffies(E * 1000)
 + secs_to_jiffies(E)
 
-@depends on patch@ expression E; @@
+@pexprms depends on patch@ expression E; @@
 
 - msecs_to_jiffies(E * MSEC_PER_SEC)
 + secs_to_jiffies(E)
+
+@r depends on report && !patch@
+constant C;
+expression E;
+position p;
+@@
+
+(
+  msecs_to_jiffies(C@p * 1000)
+|
+  msecs_to_jiffies(C@p * MSEC_PER_SEC)
+|
+  msecs_to_jiffies(E@p * 1000)
+|
+  msecs_to_jiffies(E@p * MSEC_PER_SEC)
+)
+
+@c depends on context && !patch@
+constant C;
+expression E;
+@@
+
+(
+* msecs_to_jiffies(C * 1000)
+|
+* msecs_to_jiffies(C * MSEC_PER_SEC)
+|
+* msecs_to_jiffies(E * 1000)
+|
+* msecs_to_jiffies(E * MSEC_PER_SEC)
+)
+
+@script:python depends on report@
+p << r.p;
+@@
+
+coccilib.report.print_report(p[0], "WARNING opportunity for secs_to_jiffies()")
diff --git a/scripts/const_structs.checkpatch b/scripts/const_structs.checkpatch
index e8609a03c3d8..6eb94fddc338 100644
--- a/scripts/const_structs.checkpatch
+++ b/scripts/const_structs.checkpatch
@@ -1,6 +1,7 @@
 acpi_dock_ops
 address_space_operations
 backlight_ops
+bin_attribute
 block_device_operations
 bus_type
 clk_ops
diff --git a/scripts/crypto/gen-hash-testvecs.py b/scripts/crypto/gen-hash-testvecs.py
new file mode 100755
index 000000000000..4ac927d40cf5
--- /dev/null
+++ b/scripts/crypto/gen-hash-testvecs.py
@@ -0,0 +1,147 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Script that generates test vectors for the given cryptographic hash function.
+#
+# Copyright 2025 Google LLC
+
+import hashlib
+import hmac
+import sys
+
+DATA_LENS = [0, 1, 2, 3, 16, 32, 48, 49, 63, 64, 65, 127, 128, 129, 256, 511,
+             513, 1000, 3333, 4096, 4128, 4160, 4224, 16384]
+
+# Generate the given number of random bytes, using the length itself as the seed
+# for a simple linear congruential generator (LCG).  The C test code uses the
+# same LCG with the same seeding strategy to reconstruct the data, ensuring
+# reproducibility without explicitly storing the data in the test vectors.
+def rand_bytes(length):
+    seed = length
+    out = []
+    for _ in range(length):
+        seed = (seed * 25214903917 + 11) % 2**48
+        out.append((seed >> 16) % 256)
+    return bytes(out)
+
+POLY1305_KEY_SIZE = 32
+
+# A straightforward, unoptimized implementation of Poly1305.
+# Reference: https://cr.yp.to/mac/poly1305-20050329.pdf
+class Poly1305:
+    def __init__(self, key):
+        assert len(key) == POLY1305_KEY_SIZE
+        self.h = 0
+        rclamp = 0x0ffffffc0ffffffc0ffffffc0fffffff
+        self.r = int.from_bytes(key[:16], byteorder='little') & rclamp
+        self.s = int.from_bytes(key[16:], byteorder='little')
+
+    # Note: this supports partial blocks only at the end.
+    def update(self, data):
+        for i in range(0, len(data), 16):
+            chunk = data[i:i+16]
+            c = int.from_bytes(chunk, byteorder='little') + 2**(8 * len(chunk))
+            self.h = ((self.h + c) * self.r) % (2**130 - 5)
+        return self
+
+    # Note: gen_additional_poly1305_testvecs() relies on this being
+    # nondestructive, i.e. not changing any field of self.
+    def digest(self):
+        m = (self.h + self.s) % 2**128
+        return m.to_bytes(16, byteorder='little')
+
+def hash_init(alg):
+    if alg == 'poly1305':
+        # Use a fixed random key here, to present Poly1305 as an unkeyed hash.
+        # This allows all the test cases for unkeyed hashes to work on Poly1305.