kpm: build NoMount as a KernelPatch module (6.6 and older)

.github/workflows/kpm-matrix.yml

@@ -0,0 +1,137 @@
+name: NoMount KPM — compile matrix
+
+on:
+  push:
+    branches: [dev]
+    paths:
+      - 'kernel/kpm/**'
+      - 'kernel/src/**'
+      - '.github/workflows/kpm-matrix.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: kpm-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: ${{ matrix.ver }}
+    runs-on: ubuntu-24.04
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - { ver: '4.9',  kref: 'deprecated/android-4.9-q',       tc: gcc   }
+          - { ver: '4.14', kref: 'deprecated/android-4.14-stable', tc: gcc   }
+          - { ver: '4.19', kref: 'deprecated/android-4.19-stable', tc: gcc   }
+          - { ver: '5.4',  kref: 'android11-5.4',                  tc: gcc   }
+          - { ver: '5.10', kref: 'android12-5.10',                 tc: clang }
+          - { ver: '5.15', kref: 'android13-5.15',                 tc: clang }
+          - { ver: '6.1',  kref: 'android14-6.1',                  tc: clang }
+          - { ver: '6.6',  kref: 'android15-6.6',                  tc: clang }
+    steps:
+      - uses: actions/checkout@v4
+        with: { path: repo }
+
+      - name: Toolchain
+        run: |
+          sudo apt-get update -qq
+          sudo apt-get install -y -qq gcc-aarch64-linux-gnu bc flex bison libssl-dev libelf-dev \
+                                      clang lld llvm
+          echo "clang: $(clang --version | head -1)"
+
+      - name: KernelPatch headers
+        run: git clone --depth 1 https://github.com/741afb7/KPatch-Next-EXP kp
+
+      - name: Cache kernel clone
+        id: kcache
+        uses: actions/cache@v4
+        with:
+          path: ksrc
+          key: kpm-ksrc-${{ matrix.ver }}-${{ matrix.kref }}-v1
+
+      - name: Clone kernel ${{ matrix.kref }}
+        if: steps.kcache.outputs.cache-hit != 'true'
+        run: |
+          git clone --depth 1 -b "${{ matrix.kref }}" \
+            https://android.googlesource.com/kernel/common ksrc
+          head -3 ksrc/Makefile | tr '\n' ' '
+
+      - name: Configure kernel headers
+        run: |
+          set -e -o pipefail
+          cd ksrc
+          if [ "${{ matrix.tc }}" = "clang" ]; then
+            M="ARCH=arm64 LLVM=1 LLVM_IAS=1 CROSS_COMPILE=aarch64-linux-gnu- KCFLAGS=-Wno-error"
+          else
+            M="ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- KCFLAGS=-Wno-error"
+          fi
+          if [ -f arch/arm64/configs/gki_defconfig ]; then
+            make $M gki_defconfig 2>&1 | tail -40
+          else
+            make $M defconfig 2>&1 | tail -40
+          fi
+          ./scripts/config --disable KASAN --disable FORTIFY_SOURCE \
+                           --disable DEBUG_LIST --disable PAGE_PINNER \
+                           --disable LOCKDEP --disable PROVE_LOCKING \
+                           --disable DEBUG_LOCK_ALLOC --disable TRACE_IRQFLAGS \
+                           --disable DEBUG_ATOMIC_SLEEP || true
+          make $M olddefconfig 2>&1 | tail -20
+          make $M modules_prepare 2>&1 | tail -30
+          test -f include/generated/autoconf.h || { echo "::error::prepare produced no autoconf.h"; exit 1; }
+
+      - name: Build the engine object
+        run: |
+          set -o pipefail
+          cd repo/kernel/kpm
+          if [ "${{ matrix.tc }}" = "clang" ]; then
+            CCX="clang --target=aarch64-linux-gnu"
+          else
+            CCX="aarch64-linux-gnu-gcc"
+          fi
+          make CC="$CCX" TARGET_COMPILE=aarch64-linux-gnu- \
+               KP_DIR="$GITHUB_WORKSPACE/kp" \
+               KERNEL_DIR="$GITHUB_WORKSPACE/ksrc" \
+               nm_engine.o 2>&1 | tee /tmp/kpm.log
+          ls -l nm_engine.o && echo "ENGINE_OK ${{ matrix.ver }}"
+
+      - name: Undefined symbols
+        run: |
+          cd repo/kernel/kpm
+          U=$(aarch64-linux-gnu-nm -u nm_engine.o | awk '{print $2}' | sort -u | grep -v '^nm_kpm_sym$' || true)
+          N=$(printf '%s' "$U" | grep -c . || true)
+          echo "::notice::${{ matrix.ver }} undefined=$N"
+          [ "$N" = "0" ] && exit 0
+          printf '%s\n' "$U"
+          if [ "${{ matrix.tc }}" = "clang" ]; then CCX="clang --target=aarch64-linux-gnu"; else CCX="aarch64-linux-gnu-gcc"; fi
+          make CC="$CCX" TARGET_COMPILE=aarch64-linux-gnu- \
+               KP_DIR="$GITHUB_WORKSPACE/kp" KERNEL_DIR="$GITHUB_WORKSPACE/ksrc" \
+               COMMON_EXTRA=-ffunction-sections clean >/dev/null 2>&1 || true
+          $CCX -O2 -fno-stack-protector -fno-pic -ffreestanding -w -ffunction-sections \
+            -mgeneral-regs-only -nostdinc -isystem $($CCX -print-file-name=include) \
+            -I$GITHUB_WORKSPACE/ksrc/include -I$GITHUB_WORKSPACE/ksrc/include/uapi \
+            -I$GITHUB_WORKSPACE/ksrc/include/generated -I$GITHUB_WORKSPACE/ksrc/include/generated/uapi \
+            -I$GITHUB_WORKSPACE/ksrc/arch/arm64/include -I$GITHUB_WORKSPACE/ksrc/arch/arm64/include/uapi \
+            -I$GITHUB_WORKSPACE/ksrc/arch/arm64/include/generated \
+            -I$GITHUB_WORKSPACE/ksrc/arch/arm64/include/generated/uapi \
+            -include $GITHUB_WORKSPACE/ksrc/include/linux/kconfig.h \
+            -D__KERNEL__ -DMODULE -DKBUILD_MODNAME='"nomount"' \
+            -c -o /tmp/attr.o nm_engine.c 2>/dev/null || true
+          if [ -f /tmp/attr.o ]; then
+            for sym in $U; do
+              callers=$(aarch64-linux-gnu-objdump -r /tmp/attr.o 2>/dev/null \
+                | awk -v s="$sym" '/^RELOCATION RECORDS FOR/{sec=$0} $0 ~ ("[ \t]"s"$"){print sec}' \
+                | sed 's/.*\[\.text\.//; s/\]://' | sort -u | tr '\n' ' ')
+              if [ -n "$callers" ]; then
+                echo "  $sym  <- $callers"
+              else
+                echo "  $sym  <- (no .text ref) raw records:"
+                aarch64-linux-gnu-objdump -r /tmp/attr.o 2>/dev/null \
+                  | grep -B40 "[ \t]$sym$" | grep "RELOCATION RECORDS" | tail -3 | sed 's/^/      /'
+              fi
+            done
+          fi
+          echo "::warning::${{ matrix.ver }} has $N unresolved symbol(s)"

kernel/kpm/Makefile

@@ -0,0 +1,47 @@
+ifndef TARGET_COMPILE
+    $(error TARGET_COMPILE not set, e.g. aarch64-linux-android- or aarch64-linux-gnu-)
+endif
+ifndef KP_DIR
+    $(error KP_DIR not set: checkout of KernelPatch / KPatch-Next-EXP)
+endif
+ifndef KERNEL_DIR
+    $(error KERNEL_DIR not set: configured kernel source for the TARGET KMI (<= 6.6))
+endif
+
+CC ?= $(TARGET_COMPILE)gcc
+LD ?= $(TARGET_COMPILE)ld
+
+KP_INCLUDE_DIRS := . include patch/include linux/include linux/arch/arm64/include \
+                   linux/tools/arch/arm64/include
+KP_FLAGS := $(foreach d,$(KP_INCLUDE_DIRS),-I$(KP_DIR)/kernel/$(d))
+
+CC_INCLUDE := $(shell $(CC) -print-file-name=include)
+
+K_FLAGS := -nostdinc -isystem $(CC_INCLUDE) -I$(KERNEL_DIR)/include -I$(KERNEL_DIR)/include/uapi \
+           -I$(KERNEL_DIR)/include/generated -I$(KERNEL_DIR)/include/generated/uapi \
+           -I$(KERNEL_DIR)/arch/arm64/include -I$(KERNEL_DIR)/arch/arm64/include/uapi \
+           -I$(KERNEL_DIR)/arch/arm64/include/generated \
+           -I$(KERNEL_DIR)/arch/arm64/include/generated/uapi \
+           -include $(KERNEL_DIR)/include/linux/kconfig.h \
+           -D__KERNEL__ -DMODULE -DKBUILD_MODNAME='"nomount"'
+
+COMMON := -O2 -fno-stack-protector -fno-pic -ffreestanding -Wall
+
+all: nomount.kpm
+
+nomount.kpm: nm_kpm_entry.o nm_engine.o
+	$(CC) -r -o $@ $^
+
+nm_kpm_entry.o: nm_kpm_entry.c nm_kpm_syms.h
+	$(CC) $(COMMON) $(KP_FLAGS) -c -o $@ $<
+
+nm_engine.o: nm_engine.c nm_kpm_shim.h nm_kpm_syms.h ../src/nomount.c ../src/nomount.h
+	$(CC) $(COMMON) $(K_FLAGS) -c -o $@ $<
+
+.PHONY: undefined
+undefined: nm_engine.o
+	@$(TARGET_COMPILE)nm -u $< | awk '{print $$2}' | sort -u
+
+.PHONY: clean
+clean:
+	rm -f *.o *.kpm

kernel/kpm/nm_engine.c

@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+#undef CONFIG_ARM64_LSE_ATOMICS
+
+#include <linux/version.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/dcache.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <linux/hashtable.h>
+#include <linux/rbtree.h>
+#include <linux/rwsem.h>
+#include <linux/atomic.h>
+#include <linux/cred.h>
+#include <linux/file.h>
+#include <linux/xattr.h>
+#include <linux/key-type.h>
+#include <linux/shmem_fs.h>
+#include <linux/highmem.h>
+#include <linux/compat.h>
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/jump_label.h>
+#include <linux/srcu.h>
+#include <linux/mm.h>
+#include <asm/alternative.h>
+
+#include "nm_kpm_shim.h"
+
+#define NM_KPM_BUILD 1
+#include "../src/nomount.c"
+
+#undef memcpy
+#undef memset
+#undef memmove
+
+void *memcpy(void *d, const void *s, __kernel_size_t n)
+{
+    char *dp = d; const char *sp = s;
+    while (n--) *dp++ = *sp++;
+    return d;
+}
+void *memset(void *d, int c, __kernel_size_t n)
+{
+    char *dp = d;
+    while (n--) *dp++ = (char)c;
+    return d;
+}
+void *memmove(void *d, const void *s, __kernel_size_t n)
+{
+    char *dp = d; const char *sp = s;
+    if (dp <= sp || dp >= sp + n) return memcpy(d, s, n);
+    dp += n; sp += n;
+    while (n--) *--dp = *--sp;
+    return d;
+}
+
+void *__memcpy(void *d, const void *s, __kernel_size_t n) { return memcpy(d, s, n); }
+void *__memset(void *d, int c, __kernel_size_t n) { return memset(d, c, n); }
+void *__memmove(void *d, const void *s, __kernel_size_t n) { return memmove(d, s, n); }
+
+#if defined(CONFIG_DEBUG_LIST) || defined(CONFIG_LIST_HARDENED)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 2, 0)
+bool __list_add_valid_or_report(struct list_head *new, struct list_head *prev,
+                                struct list_head *next)
+#else
+bool __list_add_valid(struct list_head *new, struct list_head *prev,
+                      struct list_head *next)
+#endif
+{
+    if (!nm_kpm_sym[NMS___list_add_valid_or_report])
+        return true;
+    return ((bool (*)(struct list_head *, struct list_head *, struct list_head *))
+            nm_kpm_sym[NMS___list_add_valid_or_report])(new, prev, next);
+}
+#endif
+
+void alt_cb_patch_nops(struct alt_instr *alt, __le32 *origptr,
+                       __le32 *updptr, int nr_inst)
+{
+    if (!nm_kpm_sym[NMS_alt_cb_patch_nops])
+        return;
+    ((void (*)(struct alt_instr *, __le32 *, __le32 *, int))
+     nm_kpm_sym[NMS_alt_cb_patch_nops])(alt, origptr, updptr, nr_inst);
+}
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 17, 0)
+void __folio_put(struct folio *folio)
+{
+    ((void (*)(struct folio *))nm_kpm_sym[NMS___folio_put])(folio);
+}
+#else
+void __put_page(struct page *page)
+{
+    ((void (*)(struct page *))nm_kpm_sym[NMS___folio_put])(page);
+}
+#endif
+
+int nm_kpm_engine_init(void)
+{
+    return nomount_init();
+}
+
+void nm_kpm_engine_exit(void)
+{
+#ifdef NOMOUNT_HAS_EXIT
+    nomount_exit();
+#endif
+}
+
+long nm_kpm_engine_ctl(const char *args)
+{
+    (void)args;
+    return 0;
+}