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author | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2018-04-24 07:36:46 +0200 |
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committer | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2018-04-24 10:24:25 +0200 |
commit | 7a8e71bd708ac77653b578c250e76c4c3271ca92 (patch) | |
tree | 7fcec03672b087d0ecd12ad0a369485a2e8ffea3 /bsps/i386/pc386/start/realmode_int.c | |
parent | bsps/m68k: Remove unused files (diff) | |
download | rtems-7a8e71bd708ac77653b578c250e76c4c3271ca92.tar.bz2 |
bsps/i386: Move shared files to bsps
This patch is a part of the BSP source reorganization.
Update #3285.
Diffstat (limited to 'bsps/i386/pc386/start/realmode_int.c')
-rw-r--r-- | bsps/i386/pc386/start/realmode_int.c | 454 |
1 files changed, 454 insertions, 0 deletions
diff --git a/bsps/i386/pc386/start/realmode_int.c b/bsps/i386/pc386/start/realmode_int.c new file mode 100644 index 0000000000..58c39c8c24 --- /dev/null +++ b/bsps/i386/pc386/start/realmode_int.c @@ -0,0 +1,454 @@ +/** + * @file realmode_int.c + * + * @ingroup i386_shared + * + * @brief Real mode interrupt call implementation + */ + +/* + * Copyright (c) 2014 - CTU in Prague + * Jan Doležal ( dolezj21@fel.cvut.cz ) + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.org/license/LICENSE. + */ + +#include <bsp/realmode_int.h> +#include <string.h> +#include <rtems/score/cpu.h> + +/* + * offsets to \a i386_realmode_interrupt_registers declared in realmode_int.h + * used in inline assmbler for better readability + */ +#define IR_EAX_OFF "0x00" +#define IR_EBX_OFF "0x04" +#define IR_ECX_OFF "0x08" +#define IR_EDX_OFF "0x0C" +#define IR_ESI_OFF "0x10" +#define IR_EDI_OFF "0x14" +#define IR_DS_OFF "0x18" +#define IR_ES_OFF "0x1A" +#define IR_FS_OFF "0x1C" +#define IR_GS_OFF "0x1E" + +/* + * offsets to \a rm_int_regs_bkp_param + */ +#define BKP_ESP_OFF "0x20" +#define BKP_SS_OFF "0x24" +#define BKP_DS_OFF "0x26" +#define RM_ENTRY "0x28" +#define PM_ENTRY "0x2C" + +/** + * @brief parameters, results, backup values accessible in real mode + * + * @note Struct members not necessarily used in C. This serves also as + * layout of memory and it is used within inline assembler. + */ +typedef struct { + i386_realmode_interrupt_registers inoutregs; + /** spot for back up of protected mode stack pointer */ + uint32_t pm_esp_bkp; + /** spot for back up of protected mode stack selector */ + uint16_t pm_ss_bkp; + /** spot for back up of protected mode data selector */ + uint16_t ds_bkp; + /** spot for setting up long indirect jump offset + to real mode from 16bit protected mode */ + uint16_t rm_entry; + /** spot for setting up long indirect jump segment + to real mode from 16bit protected mode */ + uint16_t rm_code_segment; + /** returning offset for long indirect jump back + to 32bit protected mode */ + uint32_t pm_entry; + /** returning selector for long indirect jump back + to 32bit protected mode */ + uint16_t pm_code_selector; + /* if this struct is to be modified update offset definitions as well */ +} RTEMS_PACKED rm_int_regs_bkp_param; + +/* offsets to \a pm_bkp_and_param */ +#define BKP_IDTR_LIM "0x00" +#define BKP_IDTR_BASE "0x02" +#define BKP_ES_OFF "0x06" +#define BKP_FS_OFF "0x08" +#define BKP_GS_OFF "0x0A" +#define RML_ENTRY "0x0C" +#define RML_D_SEL "0x12" +#define RM_SS "0x14" +#define RM_SP "0x16" +#define RM_DS "0x18" + +/** + * @brief backup values, pointers/parameters accessible in protected mode + * + * @note Struct members not necessarily used in C. This serves also as + * layout of memory and it is used within inline assembler. + */ +typedef struct { + /** spot for backup protected mode interrupt descriptor table register */ + uint16_t idtr_lim_bkp; + /** @see idtr_lim_bkp */ + uint32_t idtr_base_bkp; + /** spot to backup of ES register value in 32bit protected mode */ + uint16_t es_bkp; + /** spot to backup of FS register value in 32bit protected mode */ + uint16_t fs_bkp; + /** spot to backup of GS register value in 32bit protected mode */ + uint16_t gs_bkp; + /** values for indirect jump to 16bit protected mode */ + uint32_t rml_entry; + /** @see rml_entry */ + uint16_t rml_code_selector; + /** data selector for 16bit protected mode */ + uint16_t rml_data_selector; + /** values determinig location of real mode stack */ + uint16_t rm_stack_segment; + /** @see rm_stack_segment */ + uint16_t rm_stack_pointer; + /** data segment for real mode */ + uint16_t rm_data_segment; +} RTEMS_PACKED pm_bkp_and_param; + +/* addresses where we are going to put Interrupt buffer, + * parameter/returned/preserved values, stack and copy code + * for calling BIOS interrupt real mode interface + * The value is chosen arbitrarily in the first 640kB + * to be accessible for real mode. It should be out of range + * used by RTEMS because its base address is above 1MB. + * It has to be above first 4kB (or better 64kB) which could + * be used by BIOS. + */ +#define REAL_MODE_SPOT 0x12000 +/* REAL_MODE_SPOT value is also top of real mode stack */ + +/* buffers positions and lengths */ +#define DEFAULT_BUFFER_SIZE 512 +static void *default_rm_buffer_spot = (void *)REAL_MODE_SPOT; +static uint16_t default_rm_buffer_size = DEFAULT_BUFFER_SIZE; + +/* real mode stack */ +#define STACK_SIZE 8192 +#define INT_STACK_TOP REAL_MODE_SPOT + +/****************************** + * STACK * * + ****************************** REAL_MODE_SPOT + * INT_BUF * 512 B * + ****************************** + * INT_REGs * 50 B * + ****************************** + * INT_FNC *~149 B * + ******************************/ + +#define __DP_TYPE uint8_t +#define __DP_YES ((__DP_TYPE)1) +#define __DP_NO ((__DP_TYPE)-1) +#define __DP_FAIL ((__DP_TYPE)0) +static __DP_TYPE descsPrepared = __DP_NO; + +/* rml - real mode alike */ +#define rml_limit 0xFFFF +static uint16_t rml_code_dsc_index = 0; +static uint16_t rml_data_dsc_index = 0; + +/** + * @brief Prepares real-mode like descriptors to be used for switching + * to real mode. + * + * Descriptors will be placed to the GDT. + * + * @param[in] base32 32-bit physical address to be used as base for 16-bit + * protected mode descriptors + * @retval __DP_YES descriptors are prepared + * @retval __DP_FAIL descriptors allocation failed (GDT too small) + */ +static __DP_TYPE prepareRMDescriptors (void *base32) { + static void *prevBase = (void *)-1; + /* check if descriptors were prepared already */ + if (descsPrepared == __DP_YES && prevBase == base32) + return descsPrepared; + + if (descsPrepared == __DP_FAIL) + return descsPrepared; + + /* create 'real mode like' segment descriptors, for switching to real mode */ + rml_code_dsc_index = i386_next_empty_gdt_entry(); + if (rml_code_dsc_index == 0) + { + /* not enough space in GDT */ + descsPrepared = __DP_FAIL; + return descsPrepared; + } + + segment_descriptors flags_desc; + memset(&flags_desc, 0, sizeof(flags_desc)); + flags_desc.type = 0xE; /* bits 4 */ + flags_desc.descriptor_type = 0x1; /* bits 1 */ + flags_desc.privilege = 0x0; /* bits 2 */ + flags_desc.present = 0x1; /* bits 1 */ + flags_desc.available = 0x0; /* bits 1 */ + flags_desc.fixed_value_bits = 0x0; /* bits 1 */ + flags_desc.operation_size = 0x0; /* bits 1 */ + flags_desc.granularity = 0x0; /* bits 1 */ + i386_fill_segment_desc_base((unsigned)base32, &flags_desc); + i386_fill_segment_desc_limit(rml_limit, &flags_desc); + if (i386_raw_gdt_entry(rml_code_dsc_index, &flags_desc) == 0) + { + /* selector to GDT out of range */ + descsPrepared = __DP_FAIL; + return descsPrepared; + } + + rml_data_dsc_index = i386_next_empty_gdt_entry(); + if (rml_data_dsc_index == 0) + { + /* not enough space in GDT for both descriptors */ + descsPrepared = __DP_FAIL; + return descsPrepared; + } + + flags_desc.type = 0x2; /* bits 4 */ + if (i386_raw_gdt_entry(rml_data_dsc_index, &flags_desc) == 0) + { + /* selector to GDT out of range */ + descsPrepared = __DP_FAIL; + return descsPrepared; + } + prevBase = base32; + descsPrepared = __DP_YES; + return descsPrepared; +} + +void *i386_get_default_rm_buffer(uint16_t *size) { + *size = default_rm_buffer_size; + return default_rm_buffer_spot; +} + +int i386_real_interrupt_call(uint8_t interrupt_number, + i386_realmode_interrupt_registers *ir) +{ + uint32_t pagingon; + rm_int_regs_bkp_param *int_passed_regs_spot; + /* place where the code switching to realmode and executing + interrupt is coppied */ + void *rm_swtch_code_dst; + void *rm_stack_top; + + size_t cpLength; + void *cpBeg; + + /* values that can be passed from protected mode are stored in this struct + and they are passed later to the inline assembler executing interrupt */ + volatile pm_bkp_and_param pm_bkp, *pm_bkp_addr; + unsigned short unused_offset; + + __asm__ volatile( "\t" + "movl %%cr0, %%eax\n\t" + "andl %1, %%eax\n" + : "=a"(pagingon) + : "i"(CR0_PAGING) + ); + if (pagingon) + return 0; + + /* located under 1MB for real mode to be able to get/set values */ + int_passed_regs_spot = (rm_int_regs_bkp_param *) + (default_rm_buffer_spot+default_rm_buffer_size); + /* position for real mode code reallocation to the first 1MB of RAM */ + rm_swtch_code_dst = (void *)((uint32_t)int_passed_regs_spot + + sizeof(*int_passed_regs_spot)); + rm_stack_top = (void *)INT_STACK_TOP; + + if (prepareRMDescriptors(int_passed_regs_spot) != __DP_YES) + return 0; + + pm_bkp_addr = &pm_bkp; + i386_Physical_to_real( + rm_stack_top - STACK_SIZE, + (unsigned short *)&pm_bkp.rm_stack_segment, + (unsigned short *)&pm_bkp.rm_stack_pointer + ); + pm_bkp.rm_stack_pointer += STACK_SIZE; + pm_bkp.rml_code_selector = (rml_code_dsc_index<<3); + pm_bkp.rml_entry = ((uint32_t)rm_swtch_code_dst - + (uint32_t)int_passed_regs_spot); + pm_bkp.rml_data_selector = (rml_data_dsc_index<<3); + i386_Physical_to_real( + int_passed_regs_spot, + (unsigned short *)&pm_bkp.rm_data_segment, + &unused_offset + ); + + int_passed_regs_spot->inoutregs = *ir; + /* offset from the beginning of coppied code */ + uint16_t rm_entry_offset; + __asm__ volatile( + "movw $(rment-cp_beg), %0\n\t" + : "=r"(rm_entry_offset) + ); + i386_Physical_to_real( + rm_swtch_code_dst+rm_entry_offset, + (unsigned short *)&int_passed_regs_spot->rm_code_segment, + (unsigned short *)&int_passed_regs_spot->rm_entry + ); + __asm__ volatile( + "movl $(cp_end), %0\n\t" + "movw %%cs, %1\n\t" + : "=mr"(int_passed_regs_spot->pm_entry), + "=mr"(int_passed_regs_spot->pm_code_selector) + ); + /* copy code for switch to real mode and + executing interrupt to first MB of RAM */ + __asm__ volatile( "\t" + "mov $cp_end-cp_beg, %0\n\t" + "mov $cp_beg, %1\n\t" + : "=rm"(cpLength), "=rm"(cpBeg) + ); + memcpy(rm_swtch_code_dst, cpBeg, cpLength); + /* write interrupt number to be executed */ + uint16_t interrupt_number_off; + uint8_t *interrupt_number_ptr; + __asm__ volatile( "\t" + "movw $intnum-cp_beg, %0\n\t" + : "=rm"(interrupt_number_off) + ); + interrupt_number_ptr = (uint8_t *)(rm_swtch_code_dst+interrupt_number_off); + *interrupt_number_ptr = interrupt_number; + /* execute code that jumps to coppied function, which switches to real mode, + loads registers with values passed to interrupt and executes interrupt */ + __asm__ volatile( "\t" + /* backup stack */ + "movl %[regs_spot], %%ebx\n\t" + "movl %%esp, "BKP_ESP_OFF"(%%ebx)\n\t" + "movw %%ss, "BKP_SS_OFF"(%%ebx)\n\t" + /* backup data selector */ + "movw %%ds, "BKP_DS_OFF"(%%ebx)\n\t" + /* backup other selectors */ + "movl %[pm_bkp], %%esi\n\t" + "movw %%es, "BKP_ES_OFF"(%%esi)\n\t" + "movw %%fs, "BKP_FS_OFF"(%%esi)\n\t" + "movw %%gs, "BKP_GS_OFF"(%%esi)\n\t" + /* hopefully loader does not damage interrupt table on the beginning of + memory; that means length: 0x3FF, base: 0x0 */ + /* preserve idtr */ + "movl %%esi, %%eax\n\t" + "addl $"BKP_IDTR_LIM", %%eax\n\t" + "cli\n\t" + "sidt (%%eax)\n\t" + "movl $rmidt, %%eax\n\t" + "lidt (%%eax)\n\t" + /* prepare 'real mode like' data selector */ + "movw "RML_D_SEL"(%%esi), %%ax\n\t" + /* prepare real mode data segment value */ + "xorl %%edx,%%edx\n\t" + "movw "RM_DS"(%%esi), %%dx\n\t" + /* prepare real mode stack values */ + "movw "RM_SS"(%%esi), %%cx\n\t" + "movzwl "RM_SP"(%%esi), %%esp\n\t" + /* jump to copied function and */ + /* load 'real mode like' code selector */ + "ljmp *"RML_ENTRY"(%%esi)\n" +"rmidt:"/* limit and base for realmode interrupt descriptor table */ + ".word 0x3FF\n\t" + ".long 0\n\t" + /* load 'real mode like' data selectors */ +"cp_beg: .code16\n\t" + "movw %%ax, %%ss\n\t" + "movw %%ax, %%ds\n\t" + "movw %%ax, %%es\n\t" + "movw %%ax, %%fs\n\t" + "movw %%ax, %%gs\n\t" + /* disable protected mode */ + "movl %%cr0, %%eax\n\t" + "and %[cr0_prot_dis], %%ax\n\t" + "movl %%eax, %%cr0\n\t" + /* base for data selector of 16-bit protected mode is + at beginning of passed regs */ + /* flush prefetch queue by far jumping */ + "ljmp *"RM_ENTRY"\n\t" +"rment: " + /* establish rm stack - esp was already set in 32-bit protected mode*/ + "movw %%cx, %%ss\n\t" + /* set data segment (value prepared in 32-bit prot mode) */ + "movw %%dx, %%ds\n\t" + /* count real mode pointer so we don't need to overuse address + prefix (by using 32bit addresses in 16bit context) */ + "shll $4,%%edx\n\t" + "subl %%edx,%%ebx\n\t" + /* prepare values to be used after interrupt call */ + "pushw %%bx\n\t" + "pushw %%ds\n\t" + /* fill registers with parameters */ + "movw " IR_DS_OFF"(%%bx), %%ax\n\t" + "pushw %%ax\n\t" + "movl "IR_EAX_OFF"(%%bx), %%eax\n\t" + "movl "IR_ECX_OFF"(%%bx), %%ecx\n\t" + "movl "IR_EDX_OFF"(%%bx), %%edx\n\t" + "movl "IR_EDI_OFF"(%%bx), %%edi\n\t" + "movl "IR_ESI_OFF"(%%bx), %%esi\n\t" + "movw " IR_ES_OFF"(%%bx), %%es\n\t" + "movw " IR_FS_OFF"(%%bx), %%fs\n\t" + "movw " IR_GS_OFF"(%%bx), %%gs\n\t" + /* prepare ebx register */ + "movl "IR_EBX_OFF"(%%bx), %%ebx\n\t" + /* prepare ds */ + "popw %%ds\n\t" + /* interrupt instruction */ + ".byte 0xCD\n\t" +"intnum: .byte 0x0\n\t" + /* fill return structure */ + "pushw %%ds\n\t" + "pushl %%ebx\n\t" + "movw 0x6(%%esp), %%ds\n\t" + "movw 0x8(%%esp),%%bx\n\t" /* regs_spot */ + "movl %%eax,"IR_EAX_OFF"(%%bx)\n\t" + "popl %%eax\n\t" + "movl %%eax,"IR_EBX_OFF"(%%bx)\n\t" + "movl %%ecx,"IR_ECX_OFF"(%%bx)\n\t" + "movl %%edx,"IR_EDX_OFF"(%%bx)\n\t" + "movl %%esi,"IR_ESI_OFF"(%%bx)\n\t" + "movl %%edi,"IR_EDI_OFF"(%%bx)\n\t" + "popw %%ax\n\t" + "movw %%ax, " IR_DS_OFF"(%%bx)\n\t" + "movw %%es, " IR_ES_OFF"(%%bx)\n\t" + "movw %%fs, " IR_FS_OFF"(%%bx)\n\t" + "movw %%gs, " IR_GS_OFF"(%%bx)\n\t" + /* prepare protected mode data segment */ + "movw "BKP_DS_OFF"(%%bx), %%ax\n\t" + /* restore protected mode stack values */ + "movl "BKP_ESP_OFF"(%%bx),%%esp\n\t" + "movw "BKP_SS_OFF"(%%bx), %%dx\n\t" + /* return to protected mode */ + "movl %%cr0, %%ecx \n\t" + "or %[cr0_prot_ena], %%cx\n\t" + "movl %%ecx, %%cr0 \n\t" + "ljmpl *"PM_ENTRY"(%%bx)\n\t" + ".code32\n" + /* reload segmentation registers */ +"cp_end:" + "movw %%ax, %%ds\n\t" + /* restore stack segment in protected mode context */ + "movw %%dx, %%ss\n\t" + "movl %[pm_bkp], %%esi\n\t" + "movw "BKP_ES_OFF"(%%esi), %%es\n\t" + "movw "BKP_FS_OFF"(%%esi), %%fs\n\t" + "movw "BKP_GS_OFF"(%%esi), %%gs\n\t" + /* restore IDTR */ + "addl $"BKP_IDTR_LIM", %%esi\n\t" + "lidt (%%esi)\n\t" + : + : [regs_spot]"m"(int_passed_regs_spot), + [pm_bkp]"m"(pm_bkp_addr), + [cr0_prot_ena]"i"(CR0_PROTECTION_ENABLE), + [cr0_prot_dis]"i"(~CR0_PROTECTION_ENABLE) + : "memory", "ebx", "ecx", "edx", "esi", "edi" + ); + *ir = int_passed_regs_spot->inoutregs; + return 1; +} |