[PATCH 4/4] Introduce Verifying Program Loader (VPL)

Simon Glass sjg at chromium.org
Sat May 8 00:37:23 CEST 2021


Add support for VPL, a new phase of U-Boot. This runs after TPL. It is
responsible for selecting which SPL binary to run, based on a
verified-boot process.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 common/Kconfig          |  67 ++++++++++++++++
 common/spl/Kconfig      | 168 +++++++++++++++++++++++++++++++++++++++-
 common/spl/spl.c        |  25 +++++-
 doc/develop/spl.rst     |   6 +-
 include/bootstage.h     |   2 +
 include/linux/kconfig.h |   3 +
 include/spl.h           |  20 ++++-
 lib/Kconfig             |  54 +++++++++++++
 scripts/Kbuild.include  |   4 +
 scripts/Makefile.build  |   4 +
 10 files changed, 345 insertions(+), 8 deletions(-)

diff --git a/common/Kconfig b/common/Kconfig
index 26496f9a2e7..2a7f08af1dc 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -81,6 +81,15 @@ config TPL_LOGLEVEL
 	int
 	default LOGLEVEL
 
+config VPL_LOGLEVEL
+	int "loglevel for VPL"
+	default LOGLEVEL
+	help
+	  All Messages with a loglevel smaller than the console loglevel will
+	  be compiled in to VPL. See LOGLEVEL for a list of available log
+	  levels. Setting this to a value above 4 may increase the code size
+	  significantly.
+
 config SILENT_CONSOLE
 	bool "Support a silent console"
 	help
@@ -254,6 +263,15 @@ config LOG
 
 if LOG
 
+config VPL_LOG
+	bool "Enable logging support in VPL"
+	depends on LOG
+	help
+	  This enables support for logging of status and debug messages. These
+	  can be displayed on the console, recorded in a memory buffer, or
+	  discarded if not needed. Logging supports various categories and
+	  levels of severity.
+
 config LOG_MAX_LEVEL
 	int "Maximum log level to record"
 	default 6
@@ -415,6 +433,47 @@ config TPL_LOG_CONSOLE
 
 endif
 
+config VPL_LOG
+	bool "Enable logging support in VPL"
+	depends on LOG
+	help
+	  This enables support for logging of status and debug messages. These
+	  can be displayed on the console, recorded in a memory buffer, or
+	  discarded if not needed. Logging supports various categories and
+	  levels of severity.
+
+if VPL_LOG
+
+config VPL_LOG_MAX_LEVEL
+	int "Maximum log level to record in VPL"
+	default 3
+	help
+	  This selects the maximum log level that will be recorded. Any value
+	  higher than this will be ignored. If possible log statements below
+	  this level will be discarded at build time. Levels:
+
+	    0 - emergency
+	    1 - alert
+	    2 - critical
+	    3 - error
+	    4 - warning
+	    5 - note
+	    6 - info
+	    7 - debug
+	    8 - debug content
+	    9 - debug hardware I/O
+
+config VPL_LOG_CONSOLE
+	bool "Allow log output to the console in VPL"
+	default y
+	help
+	  Enables a log driver which writes log records to the console.
+	  Generally the console is the serial port or LCD display. Only the
+	  log message is shown - other details like level, category, file and
+	  line number are omitted.
+
+endif
+
 config LOG_ERROR_RETURN
 	bool "Log all functions which return an error"
 	help
@@ -711,6 +770,14 @@ config TPL_BLOBLIST
 	  This enables a bloblist in TPL. The bloblist is set up in TPL and
 	  passed to SPL and U-Boot proper.
 
+config VPL_BLOBLIST
+	bool "Support for a bloblist in VPL"
+	depends on BLOBLIST
+	default y if TPL_BLOBLIST
+	help
+	  This enables a bloblist in VPL. The bloblist is set up in VPL and
+	  passed to SPL and U-Boot proper.
+
 config BLOBLIST_SIZE
 	hex "Size of bloblist"
 	depends on BLOBLIST
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index df5468f1ac2..274686fd3ad 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -1,4 +1,4 @@
-menu "SPL / TPL"
+menu "SPL / TPL / VPL"
 
 config SUPPORT_SPL
 	bool
@@ -6,6 +6,9 @@ config SUPPORT_SPL
 config SUPPORT_TPL
 	bool
 
+config SUPPORT_VPL
+	bool
+
 config SPL_DFU_NO_RESET
 	bool
 
@@ -280,6 +283,16 @@ config SPL_READ_ONLY
 	  writeable memory) of anything it wants to modify, such as
 	  device-private data.
 
+config TPL_SEPARATE_BSS
+	bool "BSS section is in a different memory region from text"
+	default y if SPL_SEPARATE_BSS
+	help
+	  Some platforms need a large BSS region in TPL and can provide this
+	  because RAM is already set up. In this case BSS can be moved to RAM.
+	  This option should then be enabled so that the correct device tree
+	  location is used. Normally we put the device tree at the end of BSS
+	  but with this option enabled, it goes at _image_binary_end.
+
 config SPL_BANNER_PRINT
 	bool "Enable output of the SPL banner 'U-Boot SPL ...'"
 	default y
@@ -297,6 +310,15 @@ config TPL_BANNER_PRINT
 	  info. Disabling this option could be useful to reduce TPL boot time
 	  (e.g. approx. 6 ms faster, when output on i.MX6 with 115200 baud).
 
+config VPL_BANNER_PRINT
+	bool "Enable output of the VPL banner 'U-Boot VPL ...'"
+	depends on VPL
+	default y
+	help
+	  If this option is enabled, VPL will print the banner with version
+	  info. Disabling this option could be useful to reduce VPL boot time
+	  (e.g. approx. 6 ms faster, when output on i.MX6 with 115200 baud).
+
 config SPL_EARLY_BSS
 	depends on ARM && !ARM64
 	bool "Allows initializing BSS early before entering board_init_f"
@@ -817,6 +839,27 @@ config SPL_DM_SPI_FLASH
 	  Enable support for SPI DM flash drivers in SPL.
 
 endif
+
+if TPL
+
+config VPL_CACHE
+	depends on CACHE
+	bool "Support cache drivers in SPL"
+	help
+	  Enable support for cache drivers in SPL.
+
+config VPL_DM_SPI
+	bool "Support SPI DM drivers in SPL"
+	help
+	  Enable support for SPI DM drivers in SPL.
+
+config VPL_DM_SPI_FLASH
+	bool "Support SPI DM FLASH drivers in SPL"
+	help
+	  Enable support for SPI DM flash drivers in SPL.
+
+endif
+
 if SPL_UBI
 config SPL_UBI_LOAD_BY_VOLNAME
 	bool "Support loading volumes by name"
@@ -1623,6 +1666,129 @@ config TPL_YMODEM_SUPPORT
 
 endif # TPL
 
+config VPL
+	bool
+	depends on SUPPORT_SPL
+	prompt "Enable VPL"
+	help
+	  If you want to build VPL as well as the normal image, TPL and SPL,
+	  say Y.
+
+if VPL
+
+config VPL_FRAMEWORK
+	bool "Support VPL based upon the common SPL framework"
+	default y
+	help
+	  Enable the SPL framework under common/spl/ for VPL builds.
+	  This framework supports MMC, NAND and YMODEM and other methods
+	  loading of U-Boot's next stage. If unsure, say Y.
+
+config VPL_LIBCOMMON_SUPPORT
+	bool "Support common libraries"
+	default y if SPL_LIBCOMMON_SUPPORT
+	help
+	  Enable support for common U-Boot libraries within VPL. See
+	  SPL_LIBCOMMON_SUPPORT for details.
+
+config VPL_LIBGENERIC_SUPPORT
+	bool "Support generic libraries"
+	default y if SPL_LIBGENERIC_SUPPORT
+	help
+	  Enable support for generic U-Boot libraries within VPL. These
+	  libraries include generic code to deal with device tree, hashing,
+	  printf(), compression and the like. This option is enabled on many
+	  boards. Enable this option to build the code in lib/ as part of an
+	  SPL build.
+
+config VPL_DRIVERS_MISC_SUPPORT
+	bool "Support misc drivers"
+	default y if TPL_DRIVERS_MISC_SUPPORT
+	help
+	  Enable miscellaneous drivers in VPL. These drivers perform various
+	  tasks that don't fall nicely into other categories, Enable this
+	  option to build the drivers in drivers/misc as part of an VPL
+	  build, for those that support building in VPL (not all drivers do).
+
+config VPL_GPIO_SUPPORT
+	bool "Support GPIO in VPL"
+	default y if SPL_GPIO_SUPPORT
+	help
+	  Enable support for GPIOs (General-purpose Input/Output) in VPL.
+	  GPIOs allow U-Boot to read the state of an input line (high or
+	  low) and set the state of an output line. This can be used to
+	  drive LEDs, control power to various system parts and read user
+	  input. GPIOs can be useful in TPL to enable a 'sign-of-life' LED,
+	  for example. Enable this option to build the drivers in
+	  drivers/gpio as part of an TPL build.
+
+config VPL_I2C_SUPPORT
+	bool "Support I2C in VPL"
+	default y if SPL_I2C_SUPPORT
+	help
+	  Enable support for the I2C bus in TPL. Vee SPL_I2C_SUPPORT for
+	  details.
+
+config VPL_PCH_SUPPORT
+	bool "Support PCH drivers"
+	default y if TPL_PCH_SUPPORT
+	help
+	  Enable support for PCH (Platform Controller Hub) devices in VPL.
+	  These are used to set up GPIOs and the SPI peripheral early in
+	  boot. This enables the drivers in drivers/pch as part of a VPL
+	  build.
+
+config VPL_PCI
+	bool "Support PCI drivers"
+	default y if SPL_PCI
+	help
+	  Enable support for PCI in VPL. For platforms that need PCI to boot,
+	  or must perform some init using PCI in VPL, this provides the
+	  necessary driver support. This enables the drivers in drivers/pci
+	  as part of a VPL build.
+
+config VPL_RTC_SUPPORT
+	bool "Support RTC drivers"
+	help
+	  Enable RTC (Real-time Clock) support in VPL. This includes support
+	  for reading and setting the time. Some RTC devices also have some
+	  non-volatile (battery-backed) memory which is accessible if
+	  needed. This enables the drivers in drivers/rtc as part of an VPL
+	  build.
+
+config VPL_SERIAL_SUPPORT
+	bool "Support serial"
+	default y if TPL_SERIAL_SUPPORT
+	select VPL_PRINTF
+	select VPL_STRTO
+	help
+	  Enable support for serial in VPL. See SPL_SERIAL_SUPPORT for
+	  details.
+
+config VPL_SPI_SUPPORT
+	bool "Support SPI drivers"
+	help
+	  Enable support for using SPI in VPL. See SPL_SPI_SUPPORT for
+	  details.
+
+config VPL_SPI_FLASH_SUPPORT
+	bool "Support SPI flash drivers"
+	help
+	  Enable support for using SPI flash in VPL, and loading U-Boot from
+	  SPI flash. SPI flash (Serial Peripheral Bus flash) is named after
+	  the SPI bus that is used to connect it to a system. It is a simple
+	  but fast bidirectional 4-wire bus (clock, chip select and two data
+	  lines). This enables the drivers in drivers/mtd/spi as part of an
+	  VPL build. This normally requires VPL_SPI_SUPPORT.
+
+config VPL_TEXT_BASE
+	hex "VPL Text Base"
+	default 0x0
+	help
+	  The address in memory that VPL will be running from.
+
+endif
+
 config SPL_AT91_MCK_BYPASS
 	bool "Use external clock signal as a source of main clock for AT91 platforms"
 	depends on ARCH_AT91
diff --git a/common/spl/spl.c b/common/spl/spl.c
index a0a608fd772..cd428c1cbc9 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -55,6 +55,11 @@ binman_sym_declare(ulong, spl, image_pos);
 binman_sym_declare(ulong, spl, size);
 #endif
 
+#ifdef CONFIG_VPL
+binman_sym_declare(ulong, vpl, image_pos);
+binman_sym_declare(ulong, vpl, size);
+#endif
+
 /* Define board data structure */
 static struct bd_info bdata __attribute__ ((section(".data")));
 
@@ -137,21 +142,33 @@ void spl_fixup_fdt(void *fdt_blob)
 
 ulong spl_get_image_pos(void)
 {
-	return spl_phase() == PHASE_TPL ?
+#ifdef CONFIG_VPL
+	if (spl_next_phase() == PHASE_VPL)
+		return binman_sym(ulong, vpl, image_pos);
+#endif
+	return spl_next_phase() == PHASE_SPL ?
 		binman_sym(ulong, spl, image_pos) :
 		binman_sym(ulong, u_boot_any, image_pos);
 }
 
 ulong spl_get_image_size(void)
 {
-	return spl_phase() == PHASE_TPL ?
+#ifdef CONFIG_VPL
+	if (spl_next_phase() == PHASE_VPL)
+		return binman_sym(ulong, vpl, size);
+#endif
+	return spl_next_phase() == PHASE_SPL ?
 		binman_sym(ulong, spl, size) :
 		binman_sym(ulong, u_boot_any, size);
 }
 
 ulong spl_get_image_text_base(void)
 {
-	return spl_phase() == PHASE_TPL ? CONFIG_SPL_TEXT_BASE :
+#ifdef CONFIG_VPL
+	if (spl_next_phase() == PHASE_VPL)
+		return CONFIG_VPL_TEXT_BASE;
+#endif
+	return spl_next_phase() == PHASE_SPL ? CONFIG_SPL_TEXT_BASE :
 		CONFIG_SYS_TEXT_BASE;
 }
 
@@ -428,6 +445,8 @@ static enum bootstage_id get_bootstage_id(bool start)
 
 	if (IS_ENABLED(CONFIG_TPL_BUILD) && phase == PHASE_TPL)
 		return start ? BOOTSTAGE_ID_START_TPL : BOOTSTAGE_ID_END_TPL;
+	else if (IS_ENABLED(CONFIG_VPL_BUILD) && phase == PHASE_VPL)
+		return start ? BOOTSTAGE_ID_START_VPL : BOOTSTAGE_ID_END_VPL;
 	else
 		return start ? BOOTSTAGE_ID_START_SPL : BOOTSTAGE_ID_END_SPL;
 }
diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst
index c2a29a8c0a4..ede79431118 100644
--- a/doc/develop/spl.rst
+++ b/doc/develop/spl.rst
@@ -62,7 +62,11 @@ U-Boot Phases
 U-Boot boots through the following phases:
 
 TPL
-   Very early init, as tiny as possible. This loads SPL.
+   Very early init, as tiny as possible. This loads SPL (or VPL if enabled).
+
+VPL
+   Optional verification step, which can select one of several SPL binaries,
+   if A/B verified boot
 
 SPL
    Secondary program loader. Sets up SDRAM and loads U-Boot proper. It may also
diff --git a/include/bootstage.h b/include/bootstage.h
index 00c85fb86aa..23df36c8e80 100644
--- a/include/bootstage.h
+++ b/include/bootstage.h
@@ -174,6 +174,8 @@ enum bootstage_id {
 	BOOTSTAGE_ID_END_TPL,
 	BOOTSTAGE_ID_START_SPL,
 	BOOTSTAGE_ID_END_SPL,
+	BOOTSTAGE_ID_START_VPL,
+	BOOTSTAGE_ID_END_VPL,
 	BOOTSTAGE_ID_START_UBOOT_F,
 	BOOTSTAGE_ID_START_UBOOT_R,
 	BOOTSTAGE_ID_USB_START,
diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
index d109ed3119e..26f1216f7da 100644
--- a/include/linux/kconfig.h
+++ b/include/linux/kconfig.h
@@ -37,6 +37,8 @@
 
 #if defined(CONFIG_TPL_BUILD)
 #define _CONFIG_PREFIX TPL_
+#elif defined(CONFIG_VPL_BUILD)
+#define _CONFIG_PREFIX VPL_
 #elif defined(CONFIG_SPL_BUILD)
 #define _CONFIG_PREFIX SPL_
 #else
@@ -52,6 +54,7 @@
  *  CONFIG_FOO if CONFIG_SPL_BUILD is undefined,
  *  CONFIG_SPL_FOO if CONFIG_SPL_BUILD is defined.
  *  CONFIG_TPL_FOO if CONFIG_TPL_BUILD is defined.
+ *  CONFIG_VPL_FOO if CONFIG_VPL_BUILD is defined.
  */
 #define CONFIG_VAL(option)  config_val(option)
 
diff --git a/include/spl.h b/include/spl.h
index cee9a42ddb5..d9fe4e1bfd4 100644
--- a/include/spl.h
+++ b/include/spl.h
@@ -60,6 +60,7 @@ static inline bool u_boot_first_phase(void)
 enum u_boot_phase {
 	PHASE_NONE,	/* Invalid phase, signifying before U-Boot */
 	PHASE_TPL,	/* Running in TPL */
+	PHASE_VPL,	/* Running in VPL */
 	PHASE_SPL,	/* Running in SPL */
 	PHASE_BOARD_F,	/* Running in U-Boot before relocation */
 	PHASE_BOARD_R,	/* Running in U-Boot after relocation */
@@ -112,7 +113,9 @@ static inline enum u_boot_phase spl_phase(void)
 {
 #ifdef CONFIG_TPL_BUILD
 	return PHASE_TPL;
-#elif CONFIG_SPL_BUILD
+#elif defined(CONFIG_VPL_BUILD)
+	return PHASE_VPL;
+#elif defined(CONFIG_SPL_BUILD)
 	return PHASE_SPL;
 #else
 	DECLARE_GLOBAL_DATA_PTR;
@@ -134,10 +137,15 @@ static inline enum u_boot_phase spl_prev_phase(void)
 {
 #ifdef CONFIG_TPL_BUILD
 	return PHASE_NONE;
+#elif defined(CONFIG_VPL_BUILD)
+	return PHASE_TPL;	/* VPL requires TPL */
 #elif defined(CONFIG_SPL_BUILD)
-	return IS_ENABLED(CONFIG_TPL) ? PHASE_TPL : PHASE_NONE;
+	return IS_ENABLED(CONFIG_VPL) ? PHASE_VPL :
+		IS_ENABLED(CONFIG_TPL) ? PHASE_TPL :
+		PHASE_NONE;
 #else
-	return IS_ENABLED(CONFIG_SPL) ? PHASE_SPL : PHASE_NONE;
+	return IS_ENABLED(CONFIG_SPL) ? PHASE_SPL :
+		PHASE_NONE;
 #endif
 }
 
@@ -150,6 +158,8 @@ static inline enum u_boot_phase spl_prev_phase(void)
 static inline enum u_boot_phase spl_next_phase(void)
 {
 #ifdef CONFIG_TPL_BUILD
+	return IS_ENABLED(CONFIG_VPL) ? PHASE_VPL : PHASE_SPL;
+#elif defined(CONFIG_VPL_BUILD)
 	return PHASE_SPL;
 #else
 	return PHASE_BOARD_F;
@@ -166,6 +176,8 @@ static inline const char *spl_phase_name(enum u_boot_phase phase)
 	switch (phase) {
 	case PHASE_TPL:
 		return "TPL";
+	case PHASE_VPL:
+		return "VPL";
 	case PHASE_SPL:
 		return "SPL";
 	case PHASE_BOARD_F:
@@ -180,6 +192,8 @@ static inline const char *spl_phase_name(enum u_boot_phase phase)
 #ifdef CONFIG_SPL_BUILD
 # ifdef CONFIG_TPL_BUILD
 #  define SPL_TPL_NAME	"TPL"
+# elif defined(CONFIG_VPL_BUILD)
+#  define SPL_TPL_NAME	"VPL"
 # else
 #  define SPL_TPL_NAME	"SPL"
 # endif
diff --git a/lib/Kconfig b/lib/Kconfig
index 6d2d41de301..da27e71abf3 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -72,6 +72,11 @@ config TPL_PRINTF
 	select TPL_SPRINTF
 	select TPL_STRTO if !TPL_USE_TINY_PRINTF
 
+config VPL_PRINTF
+	bool
+	select VPL_SPRINTF
+	select VPL_STRTO if !VPL_USE_TINY_PRINTF
+
 config SPRINTF
 	bool
 	default y
@@ -82,6 +87,9 @@ config SPL_SPRINTF
 config TPL_SPRINTF
 	bool
 
+config VPL_SPRINTF
+	bool
+
 config SSCANF
 	bool
 	default n
@@ -96,6 +104,9 @@ config SPL_STRTO
 config TPL_STRTO
 	bool
 
+config VPL_STRTO
+	bool
+
 config IMAGE_SPARSE
 	bool
 
@@ -148,6 +159,17 @@ config TPL_USE_TINY_PRINTF
 
 	  The supported format specifiers are %c, %s, %u/%d and %x.
 
+config VPL_USE_TINY_PRINTF
+	bool "Enable tiny printf() version for VPL"
+	depends on VPL
+	help
+	  This option enables a tiny, stripped down printf version.
+	  This should only be used in space limited environments,
+	  like SPL versions with hard memory limits. This version
+	  reduces the code size by about 2.5KiB on armv7.
+
+	  The supported format specifiers are %c, %s, %u/%d and %x.
+
 config PANIC_HANG
 	bool "Do not reset the system on fatal error"
 	help
@@ -331,6 +353,17 @@ config TPL_TPM
 	  for the low-level TPM interface, but only one TPM is supported at
 	  a time by the TPM library.
 
+config VPL_TPM
+	bool "Trusted Platform Module (TPM) Support in VPL"
+	depends on VPL_DM
+	help
+	  This enables support for TPMs which can be used to provide security
+	  features for your board. The TPM can be connected via LPC or I2C
+	  and a sandbox TPM is provided for testing purposes. Use the 'tpm'
+	  command to interactive the TPM. Driver model support is provided
+	  for the low-level TPM interface, but only one TPM is supported at
+	  a time by the TPM library.
+
 endmenu
 
 menu "Android Verified Boot"
@@ -627,6 +660,27 @@ config TPL_OF_LIBFDT_ASSUME_MASK
 	  0xff means all assumptions are made and any invalid data may cause
 	  unsafe execution. See FDT_ASSUME_PERFECT, etc. in libfdt_internal.h
 
+config VPL_OF_LIBFDT
+	bool "Enable the FDT library for VPL"
+	default y if VPL_OF_CONTROL && !VPL_OF_PLATDATA
+	help
+	  This enables the FDT library (libfdt). It provides functions for
+	  accessing binary device tree images in memory, such as adding and
+	  removing nodes and properties, scanning through the tree and finding
+	  particular compatible nodes. The library operates on a flattened
+	  version of the device tree.
+
+config VPL_OF_LIBFDT_ASSUME_MASK
+	hex "Mask of conditions to assume for libfdt"
+	depends on VPL_OF_LIBFDT || FIT
+	default 0xff
+	help
+	  Use this to change the assumptions made by libfdt in SPL about the
+	  device tree it is working with. A value of 0 means that no assumptions
+	  are made, and libfdt is able to deal with malicious data. A value of
+	  0xff means all assumptions are made and any invalid data may cause
+	  unsafe execution. See FDT_ASSUME_PERFECT, etc. in libfdt_internal.h
+
 config FDT_FIXUP_PARTITIONS
 	bool "overwrite MTD partitions in DTS through defined in 'mtdparts'"
 	depends on OF_LIBFDT
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index dfb67226b08..c87d9c9f5f2 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -325,11 +325,15 @@ endif
 
 ifdef CONFIG_SPL_BUILD
 SPL_ := SPL_
+ifeq ($(CONFIG_VPL_BUILD),y)
+SPL_TPL_ := VPL_
+else
 ifeq ($(CONFIG_TPL_BUILD),y)
 SPL_TPL_ := TPL_
 else
 SPL_TPL_ := SPL_
 endif
+endif
 else
 SPL_ :=
 SPL_TPL_ :=
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 705a886cb98..b64a961f6fa 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -4,6 +4,9 @@
 # ==========================================================================
 
 # Modified for U-Boot
+prefix := vpl
+src := $(patsubst $(prefix)/%,%,$(obj))
+ifeq ($(obj),$(src))
 prefix := tpl
 src := $(patsubst $(prefix)/%,%,$(obj))
 ifeq ($(obj),$(src))
@@ -13,6 +16,7 @@ ifeq ($(obj),$(src))
 prefix := .
 endif
 endif
+endif
 
 PHONY := __build
 __build:
-- 
2.31.1.607.g51e8a6a459-goog



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