From 9f95282f31d28323d0c99b258b648936e5eadf60 Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Wed, 29 Jan 2025 22:59:18 +0100 Subject: arm64: Add late jump to kernel board hook Add empty weak assembler function armv8_switch_to_el2_prep() which is jumped to just before U-Boot determines which EL it is running in and decides which path to take to boot the Linux kernel. This weak function is meant to be used by architecture specific code to implement jump to a firmware blob, which then returns right past this weak function and continues execution of U-Boot code which then boots the Linux kernel. One example of such use case is when U-Boot jump tp TFA BL31, which switches from EL3 to EL2 and then returns to U-Boot code newly running in EL2 and starts the Linux kernel. The weak function is called with caches already disabled and DM shut down. Any preparatory work or even loading of more data must be done in board_prep_linux(), this hook is meant only for the final jump to the firmware and return to U-Boot before booting Linux. Reviewed-by: Tom Rini Signed-off-by: Marek Vasut --- arch/arm/cpu/armv8/transition.S | 8 ++++++++ arch/arm/include/asm/system.h | 16 ++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/arch/arm/cpu/armv8/transition.S b/arch/arm/cpu/armv8/transition.S index 9dbdff3a4fc..85f13ccd0d2 100644 --- a/arch/arm/cpu/armv8/transition.S +++ b/arch/arm/cpu/armv8/transition.S @@ -9,8 +9,16 @@ #include #include +.pushsection .text.armv8_switch_to_el2_prep, "ax" +WEAK(armv8_switch_to_el2_prep) + ret +ENDPROC(armv8_switch_to_el2_prep) +.popsection + .pushsection .text.armv8_switch_to_el2, "ax" ENTRY(armv8_switch_to_el2) + bl armv8_switch_to_el2_prep + nop switch_el x6, 1f, 0f, 0f 0: cmp x5, #ES_TO_AARCH64 diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h index dbf9ab43e28..091082281c7 100644 --- a/arch/arm/include/asm/system.h +++ b/arch/arm/include/asm/system.h @@ -238,6 +238,22 @@ int __asm_flush_l3_dcache(void); int __asm_invalidate_l3_icache(void); void __asm_switch_ttbr(u64 new_ttbr); +/* + * armv8_switch_to_el2_prep() - prepare for switch from EL3 to EL2 for ARMv8 + * + * @args: For loading 64-bit OS, fdt address. + * For loading 32-bit OS, zero. + * @mach_nr: For loading 64-bit OS, zero. + * For loading 32-bit OS, machine nr + * @fdt_addr: For loading 64-bit OS, zero. + * For loading 32-bit OS, fdt address. + * @arg4: Input argument. + * @entry_point: kernel entry point + * @es_flag: execution state flag, ES_TO_AARCH64 or ES_TO_AARCH32 + */ +void armv8_switch_to_el2_prep(u64 args, u64 mach_nr, u64 fdt_addr, + u64 arg4, u64 entry_point, u64 es_flag); + /* * armv8_switch_to_el2() - switch from EL3 to EL2 for ARMv8 * -- cgit v1.2.3 From 854a5a00cadd6ea4adcc9e4a923124887989f5f8 Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Wed, 29 Jan 2025 22:59:19 +0100 Subject: image: Add support for starting TFA BL31 as fitImage loadables Add support for starting TFA from U-Boot running in EL3 as part of fitImage boot, so the user can start U-Boot in the highest privilege level on the platform, bundle TFA, Linux, DT into a single fitImage and boot such a bundle as a whole. There are two main benefits of this approach. First is the ability to run U-Boot in EL3, where it has unrestricted access to the entire system and can act as a useful debug tool, as it was always intended to be used. Second is the ability to easily and safely update of any component in the fitImage, be it TFA, Linux or DT. The boot process is similar to regular Linux with DT fitImage boot process, except the TFA has to be bundled into the fitImage. For the bundling instructions, see below. The TFA is started as a 'loadables' with custom U_BOOT_FIT_LOADABLE_HANDLER and armv8_switch_to_el2_prep() handling implemented in board code, and performing the handoff and boot in case the TFA was loaded. The loadables handler is optional and meant to set up any sort of handoff structures used by the TFA BL31 or perform any other setup that is needed by the blob. The custom armv8_switch_to_el2_prep() has to implement the jump to TFA BL31 with return to U-Boot just before booting the Linux kernel. Example fitImage image and configuration section: /dts-v1/; / { description = "Linux kernel with FDT blob and TFA BL31"; images { kernel-1 { ... }; fdt-1 { ... }; atf-1 { /* This is the TFA BL31 image */ description = "TFA BL31"; data = /incbin/("../build/plat/release/bl31.bin"); type = "tfa-bl31"; arch = "arm64"; os = "arm-trusted-firmware"; compression = "none"; load = <0x46400000>; entry = <0x46400000>; }; }; configurations { default = "conf-1"; conf-1 { description = "Boot Linux"; kernel = "kernel-1"; fdt = "fdt-1"; loadables = "atf-1"; /* This is the TFA BL31 loadable */ }; }; }; Reviewed-by: Tom Rini Signed-off-by: Marek Vasut --- boot/image-fit.c | 1 + boot/image.c | 1 + include/image.h | 1 + 3 files changed, 3 insertions(+) diff --git a/boot/image-fit.c b/boot/image-fit.c index aa139da628c..41ab1f552b0 100644 --- a/boot/image-fit.c +++ b/boot/image-fit.c @@ -2175,6 +2175,7 @@ int fit_image_load(struct bootm_headers *images, ulong addr, type_ok = fit_image_check_type(fit, noffset, image_type) || fit_image_check_type(fit, noffset, IH_TYPE_FIRMWARE) || fit_image_check_type(fit, noffset, IH_TYPE_TEE) || + fit_image_check_type(fit, noffset, IH_TYPE_TFA_BL31) || (image_type == IH_TYPE_KERNEL && fit_image_check_type(fit, noffset, IH_TYPE_KERNEL_NOLOAD)); diff --git a/boot/image.c b/boot/image.c index abac254e026..139c5bd035a 100644 --- a/boot/image.c +++ b/boot/image.c @@ -183,6 +183,7 @@ static const table_entry_t uimage_type[] = { { IH_TYPE_FDT_LEGACY, "fdt_legacy", "legacy Image with Flat Device Tree ", }, { IH_TYPE_RENESAS_SPKG, "spkgimage", "Renesas SPKG Image" }, { IH_TYPE_STARFIVE_SPL, "sfspl", "StarFive SPL Image" }, + { IH_TYPE_TFA_BL31, "tfa-bl31", "TFA BL31 Image", }, { -1, "", "", }, }; diff --git a/include/image.h b/include/image.h index 8a9f779d3ff..07912606f33 100644 --- a/include/image.h +++ b/include/image.h @@ -232,6 +232,7 @@ enum image_type_t { IH_TYPE_FDT_LEGACY, /* Binary Flat Device Tree Blob in a Legacy Image */ IH_TYPE_RENESAS_SPKG, /* Renesas SPKG image */ IH_TYPE_STARFIVE_SPL, /* StarFive SPL image */ + IH_TYPE_TFA_BL31, /* TFA BL31 image */ IH_TYPE_COUNT, /* Number of image types */ }; -- cgit v1.2.3