[RFC][PATCH 1/3] 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.
Signed-off-by: Marek Vasut marek.vasut+renesas@mailbox.org --- Cc: Andre Przywara andre.przywara@arm.com Cc: Caleb Connolly caleb.connolly@linaro.org Cc: Igor Opaniuk igor.opaniuk@gmail.com Cc: Ilias Apalodimas ilias.apalodimas@linaro.org Cc: Julien Masson jmasson@baylibre.com Cc: Mattijs Korpershoek mkorpershoek@baylibre.com Cc: Maxim Moskalets maximmosk4@gmail.com Cc: Michael Walle mwalle@kernel.org Cc: Nobuhiro Iwamatsu iwamatsu@nigauri.org Cc: Patrick Rudolph patrick.rudolph@9elements.com Cc: Paul Barker paul.barker.ct@bp.renesas.com Cc: Paul-Erwan Rio paulerwan.rio@gmail.com Cc: Peter Hoyes Peter.Hoyes@arm.com Cc: Raymond Mao raymond.mao@linaro.org Cc: Sam Protsenko semen.protsenko@linaro.org Cc: Simon Glass sjg@chromium.org Cc: Sughosh Ganu sughosh.ganu@linaro.org Cc: Tom Rini trini@konsulko.com Cc: u-boot@lists.denx.de --- 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 <linux/linkage.h> #include <asm/macro.h>
+.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 *
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 */ }; }; };
Signed-off-by: Marek Vasut marek.vasut+renesas@mailbox.org --- Cc: Andre Przywara andre.przywara@arm.com Cc: Caleb Connolly caleb.connolly@linaro.org Cc: Igor Opaniuk igor.opaniuk@gmail.com Cc: Ilias Apalodimas ilias.apalodimas@linaro.org Cc: Julien Masson jmasson@baylibre.com Cc: Mattijs Korpershoek mkorpershoek@baylibre.com Cc: Maxim Moskalets maximmosk4@gmail.com Cc: Michael Walle mwalle@kernel.org Cc: Nobuhiro Iwamatsu iwamatsu@nigauri.org Cc: Patrick Rudolph patrick.rudolph@9elements.com Cc: Paul Barker paul.barker.ct@bp.renesas.com Cc: Paul-Erwan Rio paulerwan.rio@gmail.com Cc: Peter Hoyes Peter.Hoyes@arm.com Cc: Raymond Mao raymond.mao@linaro.org Cc: Sam Protsenko semen.protsenko@linaro.org Cc: Simon Glass sjg@chromium.org Cc: Sughosh Ganu sughosh.ganu@linaro.org Cc: Tom Rini trini@konsulko.com Cc: u-boot@lists.denx.de --- 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 7d56f0b5e6e..9ee98bef817 100644 --- a/boot/image-fit.c +++ b/boot/image-fit.c @@ -2166,6 +2166,7 @@ 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 9be5acd8158..90bd88ab3c2 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 */ };
Implement custom U_BOOT_FIT_LOADABLE_HANDLER and armv8_switch_to_el2_prep() handling in case the TFA was loaded. The loadables handler sets up custom handoff structure used by Renesas TFA fork in fixed location in DRAM and indicates the TFA has been loaded.
The custom armv8_switch_to_el2_prep() handling tests whether the TFA BL31 was previously loaded and the custom handoff structure was set up, and if so, jumps to TFA BL31 which switches from EL3 to EL2 and then returns to U-Boot just past bl in armv8_switch_to_el2() to finish starting the Linux kernel.
The jump to Linux through TFA works in such a way that the custom armv8_switch_to_el2_prep() handler configures the custom handoff structure such that the target jump address of the TFA BL31 on exit is set to the armv8_switch_to_el2() + 4, which is just past the bl, and just before the U-Boot code which implements the Linux kernel boot from either EL. The registers passed through the TFA BL31 are all the registers passed into armv8_switch_to_el2_prep() to assure maximum compatibility with all the boot modes. The armv8_switch_to_el2_prep() handler jumps to the TFA BL31, which does its setup, drops EL from EL3 to EL2 and finally jumps to the armv8_switch_to_el2() + 4 entry point, which then allows U-Boot to boot the Linux kernel the usual way.
In order to build suitable kernel fitImage, build TFA first, temporarily from downstream repository: remote: https://github.com/renesas-rcar/arm-trusted-firmware.git branch: rcar_gen4_v2.7_v4x
``` $ git clean -fqdx $ MBEDTLS_DIR=/path/to/mbedtls/ make -j$(nproc) bl31 \ PLAT=rcar_gen4 ARCH=aarch64 LSI=V4H SPD=none \ CTX_INCLUDE_AARCH32_REGS=0 MBEDTLS_COMMON_MK=1 \ PTP_NONSECURE_ACCESS=1 LOG_LEVEL=20 DEBUG=0 \ ENABLE_ASSERTIONS=0 E=0 ```
Build Linux kernel Image and device tree from current mainline Linux kernel repository, obtain 'Image' and 'r8a779g0-white-hawk.dtb' .
Bundle the files together using provided fit-image.its fitImage description: ``` $ mkimage -f fit-image.its fitImage ```
To start the kernel fiImage generated in previous step, load fitImage to DRAM and use the 'bootm' command to start it: => load 0x58000000 ... fitImage && bootm 0x58000000
Signed-off-by: Marek Vasut marek.vasut+renesas@mailbox.org --- Cc: Andre Przywara andre.przywara@arm.com Cc: Caleb Connolly caleb.connolly@linaro.org Cc: Igor Opaniuk igor.opaniuk@gmail.com Cc: Ilias Apalodimas ilias.apalodimas@linaro.org Cc: Julien Masson jmasson@baylibre.com Cc: Mattijs Korpershoek mkorpershoek@baylibre.com Cc: Maxim Moskalets maximmosk4@gmail.com Cc: Michael Walle mwalle@kernel.org Cc: Nobuhiro Iwamatsu iwamatsu@nigauri.org Cc: Patrick Rudolph patrick.rudolph@9elements.com Cc: Paul Barker paul.barker.ct@bp.renesas.com Cc: Paul-Erwan Rio paulerwan.rio@gmail.com Cc: Peter Hoyes Peter.Hoyes@arm.com Cc: Raymond Mao raymond.mao@linaro.org Cc: Sam Protsenko semen.protsenko@linaro.org Cc: Simon Glass sjg@chromium.org Cc: Sughosh Ganu sughosh.ganu@linaro.org Cc: Tom Rini trini@konsulko.com Cc: u-boot@lists.denx.de --- board/renesas/rcar-common/gen4-common.c | 118 ++++++++++++++++++++++++ 1 file changed, 118 insertions(+)
diff --git a/board/renesas/rcar-common/gen4-common.c b/board/renesas/rcar-common/gen4-common.c index 2abe9660cf8..2ca9fbe7851 100644 --- a/board/renesas/rcar-common/gen4-common.c +++ b/board/renesas/rcar-common/gen4-common.c @@ -7,11 +7,13 @@
#include <asm/arch/renesas.h> #include <asm/arch/sys_proto.h> +#include <asm/armv8/mmu.h> #include <asm/global_data.h> #include <asm/io.h> #include <asm/mach-types.h> #include <asm/processor.h> #include <asm/system.h> +#include <image.h> #include <linux/errno.h>
#define RST_BASE 0xE6160000 /* Domain0 */ @@ -88,3 +90,119 @@ int ft_board_setup(void *blob, struct bd_info *bd) { return 0; } + +/* R-Car Gen4 TFA BL31 handoff structure and handling. */ +struct param_header { + u8 type; + u8 version; + u16 size; + u32 attr; +}; + +struct tfa_image_info { + struct param_header h; + uintptr_t image_base; + u32 image_size; + u32 image_max_size; +}; + +struct aapcs64_params { + u64 arg0; + u64 arg1; + u64 arg2; + u64 arg3; + u64 arg4; + u64 arg5; + u64 arg6; + u64 arg7; +}; + +struct entry_point_info { + struct param_header h; + uintptr_t pc; + u32 spsr; + struct aapcs64_params args; +}; + +struct bl2_to_bl31_params_mem { + struct tfa_image_info bl32_image_info; + struct tfa_image_info bl33_image_info; + struct entry_point_info bl33_ep_info; + struct entry_point_info bl32_ep_info; +}; + +/* Default jump address, return to U-Boot */ +#define BL33_BASE 0x44100000 +/* Custom parameters address passed to TFA by ICUMXA loader */ +#define PARAMS_BASE 0x46422200 + +/* Usually such a structure is produced by ICUMXA and passed in at 0x46422200 */ +static const struct bl2_to_bl31_params_mem blinfo_template = { + .bl33_ep_info.h.type = 1, /* PARAM_EP */ + .bl33_ep_info.h.version = 2, /* Version 2 */ + .bl33_ep_info.h.size = sizeof(struct entry_point_info), + .bl33_ep_info.h.attr = 0x81, /* Executable | Non-Secure */ + .bl33_ep_info.spsr = 0x2c9, /* Mode=EL2, SP=ELX, Exceptions=OFF */ + .bl33_ep_info.pc = BL33_BASE, + + .bl33_image_info.h.type = 1, /* PARAM_EP */ + .bl33_image_info.h.version = 2, /* Version 2 */ + .bl33_image_info.h.size = sizeof(struct image_info), + .bl33_image_info.h.attr = 0, + .bl33_image_info.image_base = BL33_BASE, +}; + +static bool tfa_bl31_image_loaded; +static ulong tfa_bl31_image_addr; + +static void tfa_bl31_image_process(ulong image, size_t size) +{ + /* Custom parameters address passed to TFA by ICUMXA loader */ + struct bl2_to_bl31_params_mem *blinfo = (struct bl2_to_bl31_params_mem *)PARAMS_BASE; + + /* Clear a page and copy template */ + memset((void *)PARAMS_BASE, 0, PAGE_SIZE); + memcpy(blinfo, &blinfo_template, sizeof(*blinfo)); + tfa_bl31_image_addr = image; + tfa_bl31_image_loaded = true; +} + +U_BOOT_FIT_LOADABLE_HANDLER(IH_TYPE_TFA_BL31, tfa_bl31_image_process); + +void armv8_switch_to_el2_prep(u64 args, u64 mach_nr, u64 fdt_addr, + u64 arg4, u64 entry_point, u64 es_flag) +{ + typedef void __noreturn (*image_entry_noargs_t)(void); + image_entry_noargs_t image_entry = + (image_entry_noargs_t)(void *)tfa_bl31_image_addr; + struct bl2_to_bl31_params_mem *blinfo = + (struct bl2_to_bl31_params_mem *)PARAMS_BASE; + + /* + * Destination address in arch/arm/cpu/armv8/transition.S + * right past the first bl in armv8_switch_to_el2() to let + * the rest of U-Boot pre-Linux code run. The code does run + * without stack pointer! + */ + const u64 ep = ((u64)(uintptr_t)&armv8_switch_to_el2) + 4; + + /* If TFA BL31 was not part of the fitImage, do regular boot. */ + if (!tfa_bl31_image_loaded) + return; + + /* + * Set up kernel entry point and parameters: + * x0 is FDT address, x1..x3 must be 0 + */ + blinfo->bl33_ep_info.pc = ep; + blinfo->bl33_ep_info.args.arg0 = args; + blinfo->bl33_ep_info.args.arg1 = mach_nr; + blinfo->bl33_ep_info.args.arg2 = fdt_addr; + blinfo->bl33_ep_info.args.arg3 = arg4; + blinfo->bl33_ep_info.args.arg4 = entry_point; + blinfo->bl33_ep_info.args.arg5 = es_flag; + blinfo->bl33_image_info.image_base = ep; + + /* Jump to TFA BL31 */ + image_entry(); +}
participants (1)
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Marek Vasut