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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Minios-devel] [UNIKRAFT/PLAT_RASPI PATCH 02/13] plats/raspi: Adding assembly CPU start file
start.S is the file containing the initial code run by all cores in the platform at boot time. Several things are happening here. 1- We first read the RTC from the SoC, to know how much time the GPU took for booting and reseting the CPU. 2- We check the id of the cores, and halt any core other than core 0. 3- Configure main CPU registers to our needs. 4- Enter EL1 and setup the page tables. 5- If selected in the menuconfig, watermark the stack to measure the stack usage. 6- Clear the BSS region. 7- Setup the stack pointer. 8- Restore the value of the RTC measured at the beginning of the file and jump to _libraspiplat_entry. Signed-off-by: Santiago Pagani <santiagopagani@xxxxxxxxx> --- start.S | 198 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 198 insertions(+) create mode 100644 start.S diff --git a/start.S b/start.S new file mode 100644 index 0000000..04c938d --- /dev/null +++ b/start.S @@ -0,0 +1,198 @@ +/* + * Copyright (C) 2018, bzt (bztsrc@github), https://github.com/bztsrc/raspi3-tutorial + * Copyright (c) 2018, Sergey Matyukevich <https://github.com/s-matyukevich/raspberry-pi-os> + * (c) 2020, Santiago Pagani <santiagopagani@xxxxxxxxx> + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, + * modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT + * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, + * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER + * DEALINGS IN THE SOFTWARE. + * + */ + +#include <raspi/sysregs.h> +#include <raspi/mm.h> +#include <raspi/mmu.h> +#include <uk/config.h> + +.section ".text.boot" + +.global _start +_start: + // read cpu id, stop slave cores + ldr x0, =0x3F003000 + ldr w10, [x0, #4] + ldr w11, [x0, #8] + ldr w12, [x0, #4] + ldr w13, [x0, #8] + mrs x1, mpidr_el1 + and x1, x1, #3 + cbz x1, master + +// If the cpu id is > 0, hang here +hang: wfe + b hang + +// Continue if cpu id == 0 +master: + ldr x0, =SCTLR_EL1_VALUE_MMU_DISABLED + msr sctlr_el1, x0 + + ldr x0, =SCTLR_EL2_VALUE + msr sctlr_el2, x0 + +// Disable coprocessor traps + ldr x0, =CPACR_EL1_VALUE + msr cpacr_el1, x0 + + ldr x0, =HCR_EL2_VALUE + msr hcr_el2, x0 + + // Set the SPSR state to restore when returning from EL2 to EL1 + ldr x0, =SPSR_EL2_VALUE + msr spsr_el2, x0 + + adr x0, el1_entry + msr elr_el2, x0 + + ldr x0, =0x40000040 + ldr w14, [x0] + orr w14, w14, #8 + str w14, [x0] + + eret + +el1_entry: + bl create_page_tables + + adrp x0, _pagetables + msr ttbr1_el1, x0 + msr ttbr0_el1, x0 + + ldr x0, =(TCR_VALUE) + msr tcr_el1, x0 + + ldr x0, =(MAIR_VALUE) + msr mair_el1, x0 + + ldr x4, =_libraspiplat_entry + ldr x5, =SCTLR_EL1_VALUE_MMU_ENABLED + msr sctlr_el1, x5 + + +#if CONFIG_RASPI_WATERMARK_STACK +watermark_stack_start: + ldr x1, =VA_START + ldr w2, =0x10000 +watermark_stack_loop: + cbz w2, watermark_stack_done + str x2, [x1], #8 + sub w2, w2, #1 + cbnz w2, watermark_stack_loop +watermark_stack_done: +#endif + + +clear_bss_start: + // Clear bss + ldr x1, =__bss_start + ldr w2, =__bss_size +clear_bss_loop: + cbz w2, clear_bss_done + str xzr, [x1], #8 + sub w2, w2, #1 + cbnz w2, clear_bss_loop +clear_bss_done: + + + // Set the stack before our code + msr SPSel, #1 + ldr x1, =_start + mov sp, x1 + + +jump_to_C: +// Recover initial timer value + mov w0, w10 + mov w1, w11 + mov w2, w12 + mov w3, w13 + //bl _libraspiplat_entry + br x4 + + // As a failsafe, we also hang the main core + b hang + + + + + + .macro create_pgd_entry, tbl, virt, tmp1, tmp2 + create_table_entry \tbl, \virt, PGD_SHIFT, \tmp1, \tmp2 + create_table_entry \tbl, \virt, PUD_SHIFT, \tmp1, \tmp2 + .endm + + .macro create_table_entry, tbl, virt, shift, tmp1, tmp2 + lsr \tmp1, \virt, #\shift + and \tmp1, \tmp1, #PTRS_PER_TABLE - 1 // table index + add \tmp2, \tbl, #PAGE_SIZE + orr \tmp2, \tmp2, #MM_TYPE_PAGE_TABLE + str \tmp2, [\tbl, \tmp1, lsl #3] + add \tbl, \tbl, #PAGE_SIZE // next level table page + .endm + + .macro create_block_map, tbl, phys, start, end, flags, tmp1 + lsr \start, \start, #SECTION_SHIFT + and \start, \start, #PTRS_PER_TABLE - 1 // table index + lsr \end, \end, #SECTION_SHIFT + and \end, \end, #PTRS_PER_TABLE - 1 // table end index + lsr \phys, \phys, #SECTION_SHIFT + mov \tmp1, #\flags + orr \phys, \tmp1, \phys, lsl #SECTION_SHIFT // table entry +9999: str \phys, [\tbl, \start, lsl #3] // store the entry + add \start, \start, #1 // next entry + add \phys, \phys, #SECTION_SIZE // next block + cmp \start, \end + b.ls 9999b + .endm + +create_page_tables: + mov x29, x30 // save return address + + adrp x0, _pagetables + mov x1, #PG_DIR_SIZE + bl memzero + + adrp x0, _pagetables + mov x1, #VA_START + create_pgd_entry x0, x1, x2, x3 + + /* Mapping kernel and init stack*/ + mov x1, xzr // start mapping from physical offset 0 + mov x2, #VA_START // first virtual address + ldr x3, =(VA_START + DEVICE_BASE - SECTION_SIZE) // last virtual address + create_block_map x0, x1, x2, x3, MMU_FLAGS, x4 + + /* Mapping device memory*/ + mov x1, #DEVICE_BASE // start mapping from device base address + ldr x2, =(VA_START + DEVICE_BASE) // first virtual address + ldr x3, =(VA_START + PHYS_MEMORY_SIZE - SECTION_SIZE) // last virtual address + create_block_map x0, x1, x2, x3, MMU_DEVICE_FLAGS, x4 + + mov x30, x29 // restore return address + ret -- 2.17.1 _______________________________________________ Minios-devel mailing list Minios-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/minios-devel
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