ci: build debug kernels

Enabling ftrace in our kernels changed the performance of several tests,
so it was reverted.

Make a new set of kernels that will not be used for performance tests.

While doing this, simplify our guest kernel config customization that
relied on patches and use file concatenation instead. Turns out `make
olddefconfig` produces the same result and we avoid the complexity of
dealing with patches.

Signed-off-by: Pablo Barbáchano <pablob@amazon.com>

Author: pb8o

resources/guest_configs/ci.config

@@ -0,0 +1,6 @@
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_MSDOS_PARTITION=y
+# aarch64 only TBD split into a separate file
+CONFIG_DEVMEM=y
+# CONFIG_ARM64_ERRATUM_3194386 is not set

resources/guest_configs/ftrace.config

@@ -0,0 +1,11 @@
+CONFIG_FTRACE=y
+CONFIG_FUNCTION_TRACER=y
+CONFIG_FUNCTION_GRAPH_TRACER=y
+CONFIG_IRQSOFF_TRACER=y
+CONFIG_PREEMPT_TRACER=y
+CONFIG_SCHED_TRACER=y
+CONFIG_STACK_TRACER=y
+CONFIG_BLK_DEV_IO_TRACE=y
+CONFIG_FUNCTION_PROFILER=y
+CONFIG_FTRACE_MCOUNT_RECORD=y
+CONFIG_FTRACE_SYSCALLS=y

resources/guest_configs/patches/0001-fix-Adjust-config-options-for-what-is-needed-by-our-.patch

@@ -134,12 +134,6 @@ function clone_amazon_linux_repo {
     [ -d linux ] || git clone https://github.com/amazonlinux/linux linux
 }
 
-function apply_kernel_patches_for_ci {
-    for p in $PWD/guest_configs/patches/* ; do
-        patch -p2 < $p
-    done
-}
-
 # prints the git tag corresponding to the newest and best matching the provided kernel version $1
 # this means that if a microvm kernel exists, the tag returned will be of the form
 #
@@ -179,8 +173,9 @@ function build_al_kernel {
         echo "FATAL: Unsupported architecture!"
         exit 1
     fi
-    cp "$KERNEL_CFG" .config
-
+    # Concatenate all config files into one. olddefconfig will then resolve
+    # as needed. Later values override earlier ones.
+    cat "$@" >.config
     make olddefconfig
     make -j $(nproc) $target
     LATEST_VERSION=$(cat include/config/kernel.release)
@@ -223,22 +218,24 @@ function build_al_kernels {
 
     clone_amazon_linux_repo
 
-    # Apply kernel patches on top of AL configuration
-    apply_kernel_patches_for_ci
+    CI_CONFIG="$PWD/guest_configs/ci.config"
+    FTRACE_CONFIG="$PWD/guest_configs/ftrace.config"
 
     if [[ "$KERNEL_VERSION" == @(all|5.10) ]]; then
-        build_al_kernel $PWD/guest_configs/microvm-kernel-ci-$ARCH-5.10.config
+        build_al_kernel $PWD/guest_configs/microvm-kernel-ci-$ARCH-5.10.config "$CI_CONFIG"
     fi
     if [[ $ARCH == "x86_64" && "$KERNEL_VERSION" == @(all|5.10-no-acpi) ]]; then
-        build_al_kernel $PWD/guest_configs/microvm-kernel-ci-$ARCH-5.10-no-acpi.config
+        build_al_kernel $PWD/guest_configs/microvm-kernel-ci-$ARCH-5.10-no-acpi.config "$CI_CONFIG"
     fi
     if [[ "$KERNEL_VERSION" == @(all|6.1) ]]; then
-        build_al_kernel $PWD/guest_configs/microvm-kernel-ci-$ARCH-6.1.config 5.10
+        build_al_kernel $PWD/guest_configs/microvm-kernel-ci-$ARCH-6.1.config "$CI_CONFIG"
     fi
 
-    # Undo kernel patches on top of AL configuration
-    git restore $PWD/guest_configs
-    rm -rf $PWD/guest_configs/*.orig
+    # Build debug kernels
+    OUTPUT_DIR=$OUTPUT_DIR/debug
+    mkdir -pv $OUTPUT_DIR
+    build_al_kernel "$PWD/guest_configs/microvm-kernel-ci-$ARCH-5.10.config" "$CI_CONFIG" "$FTRACE_CONFIG"
+    build_al_kernel "$PWD/guest_configs/microvm-kernel-ci-$ARCH-6.1.config" "$CI_CONFIG" "$FTRACE_CONFIG"
 }
 
 function print_help {