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https://github.com/taigrr/gopher-os
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tools: update offsets tool to work with go versions 1.7 - 1.10
Older go versions (1.7.x) specify a fixed page size (_PageSize const) as part of their runtime whereas newer go versions populate the page size at runtime. The kernel asm bootstrap code was written with go 1.8 in mind. As a result it attempts to populate the page size manually which obviously breaks compilation in go 1.7. The offsets tool has been updated to emit the special def "SKIP_PAGESIZE_SETUP" when running under go 1.7 which allows us to perform conditional compilation of the page setup code inside the bootstrap asm code. fixup
This commit is contained in:
Achilleas Anagnostopoulos
@@ -17,17 +17,17 @@ _rt0_idt_desc:
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resw 1
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resq 1
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; Allocates space for the IRQ handlers pointers registered by the IRQ package
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; Allocates space for the IRQ handlers pointers registered by the IRQ package
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_rt0_irq_handlers resq IDT_ENTRIES
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; According to the "ELF handling for TLS" document section 3.4.6
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; (https://www.akkadia.org/drepper/tls.pdf) for the GNU variant for x86-64,
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; fs:0x00 contains a pointer to the TCB. Variables in the TLS are stored
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; fs:0x00 contains a pointer to the TCB. Variables in the TLS are stored
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; before the TCB and are accessed using negative offsets from the TCB address.
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r0_g_ptr: resq 1
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tcb_ptr: resq 1
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r0_g_ptr: resq 1
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tcb_ptr: resq 1
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section .text
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section .text
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;------------------------------------------------------------------------------
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; Kernel 64-bit entry point
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@@ -36,7 +36,7 @@ section .text
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; - it has entered long mode and enabled paging
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; - it has loaded a 64bit GDT
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; - it has set up identity paging for the physical 0-8M region and the
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; PAGE_OFFSET to PAGE_OFFSET+8M region.
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; PAGE_OFFSET to PAGE_OFFSET+8M region.
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;------------------------------------------------------------------------------
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global _rt0_64_entry
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_rt0_64_entry:
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@@ -50,7 +50,7 @@ _rt0_64_entry:
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extern _kernel_start
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extern _kernel_end
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extern kernel.Kmain
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mov rax, PAGE_OFFSET
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push rax
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mov rax, _kernel_end - PAGE_OFFSET
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@@ -60,7 +60,7 @@ _rt0_64_entry:
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mov rax, multiboot_data
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push rax
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call kernel.Kmain
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; Main should never return; halt the CPU
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mov rdi, err_kmain_returned
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call write_string
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@@ -75,13 +75,15 @@ _rt0_64_entry:
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_rt0_64_setup_go_runtime_structs:
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%include "go_asm_offsets.inc" ; generated by tools/offsets
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%ifndef SKIP_PAGESIZE_SETUP
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; The Go allocator expects this symbol to be set to the system page size
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; As the kernel bypass osinit() this needs to be set here.
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; As the kernel bypasses osinit() this needs to be manually set here.
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extern runtime.physPageSize
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mov rax, runtime.physPageSize
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mov qword [rax], 0x1000 ; 4096
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; Setup r0_g stack limits using the reserved stack
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%endif
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; Setup r0_g stack limits using the reserved stack
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extern stack_top
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extern stack_bottom
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extern runtime.g0
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@@ -99,21 +101,21 @@ _rt0_64_setup_go_runtime_structs:
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mov qword [rbx+GO_M_G0], rsi ; m.g0 = g0
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mov qword [rsi+GO_G_M], rbx ; g.m = m
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; Store the address of g0 in r0_g_ptr
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; Store the address of g0 in r0_g_ptr
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mov rax, r0_g_ptr
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mov qword [rax], rsi
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; According to the x86-64 ABI requirements fs:0x0 should point to the
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; According to the x86-64 ABI requirements fs:0x0 should point to the
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; TCB.
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mov rax, tcb_ptr
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mov qword [rax], rax
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; Load 64-bit FS register address
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; eax -> lower 32 bits
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; Load 64-bit FS register address
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; eax -> lower 32 bits
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; edx -> upper 32 bits
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mov ecx, 0xc0000100 ; fs_base
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mov rsi, tcb_ptr
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mov rax, rsi ; lower 32 bits
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mov rax, rsi ; lower 32 bits
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shr rsi, 32
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mov rdx, rsi ; high 32 bits
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wrmsr
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@@ -122,26 +124,26 @@ _rt0_64_setup_go_runtime_structs:
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;------------------------------------------------------------------------------
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; Setup and load IDT. We preload each IDT entry with a pointer to a gate handler
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; but set it as inactive. The code in irq_amd64 is responsible for enabling
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; Setup and load IDT. We preload each IDT entry with a pointer to a gate handler
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; but set it as inactive. The code in irq_amd64 is responsible for enabling
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; individual IDT entries when handlers are installed.
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;------------------------------------------------------------------------------
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_rt0_64_load_idt:
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mov rax, _rt0_idt_start
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%assign gate_num 0
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%assign gate_num 0
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%rep IDT_ENTRIES
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mov rbx, _rt0_64_gate_entry_%+ gate_num
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mov word [rax], bx ; gate entry bits 0-15
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mov word [rax+2], 0x8 ; GDT descriptor
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mov byte [rax+5], 0x0 ; Mark the entry as NOT present
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mov byte [rax+5], 0x0 ; Mark the entry as NOT present
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shr rbx, 16
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mov word [rax+6], bx ; gate entry bits 16-31
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shr rbx, 16
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mov dword [rax+8], ebx ; gate entry bits 32-63
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add rax, 16 ; size of IDT entry
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%assign gate_num gate_num+1
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%assign gate_num gate_num+1
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%endrep
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mov rax, _rt0_idt_desc
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mov word [rax], _rt0_idt_end - _rt0_idt_start - 1 ; similar to GDT this must be len(IDT) - 1
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@@ -152,15 +154,15 @@ ret
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;------------------------------------------------------------------------------
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; Generate gate entries. Each gate handler pushes the address of the registered
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; Generate gate entries. Each gate handler pushes the address of the registered
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; handler to the stack before jumping to a dispatcher function.
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;
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; Some exceptions push an error code to the stack after the stack frame. This
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; code must be popped off the stack before calling iretq. The generated handlers
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; are aware whether they need to deal with the code or not and jump to the
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; code must be popped off the stack before calling iretq. The generated handlers
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; are aware whether they need to deal with the code or not and jump to the
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; appropriate get dispatcher.
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;------------------------------------------------------------------------------
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%assign gate_num 0
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%assign gate_num 0
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%rep IDT_ENTRIES
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extern _rt0_interrupt_handlers
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_rt0_64_gate_entry_%+ gate_num:
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@@ -177,13 +179,13 @@ _rt0_64_gate_entry_%+ gate_num:
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%else
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jmp _rt0_64_gate_dispatcher_without_code
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%endif
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%assign gate_num gate_num+1
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%assign gate_num gate_num+1
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%endrep
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%macro save_regs 0
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push r15
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push r15
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push r14
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push r13
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push r13
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push r12
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push r11
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push r10
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@@ -191,10 +193,10 @@ _rt0_64_gate_entry_%+ gate_num:
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push r8
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push rbp
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push rdi
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push rsi
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push rdx
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push rcx
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push rbx
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push rsi
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push rdx
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push rcx
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push rbx
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push rax
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%endmacro
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@@ -203,13 +205,13 @@ _rt0_64_gate_entry_%+ gate_num:
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pop rbx
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pop rcx
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pop rdx
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pop rsi
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pop rsi
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pop rdi
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pop rbp
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pop rbp
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pop r8
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pop r9
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pop r10
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pop r11
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pop r11
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pop r12
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pop r13
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pop r14
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@@ -217,14 +219,14 @@ _rt0_64_gate_entry_%+ gate_num:
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%endmacro
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;------------------------------------------------------------------------------
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; This dispatcher is invoked by gate entries that expect a code to be pushed
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; This dispatcher is invoked by gate entries that expect a code to be pushed
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; by the CPU to the stack. It performs the following functions:
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; - save registers
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; - push pointer to saved regs
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; - push pointer to stack frame
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; - read and push exception code
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; - push pointer to saved regs
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; - push pointer to stack frame
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; - read and push exception code
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; - invoke handler(code, &frame, ®s)
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; - restore registers
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; - restore registers
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; - pop exception code from stack so rsp points to the stack frame
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;------------------------------------------------------------------------------
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_rt0_64_gate_dispatcher_with_code:
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@@ -236,7 +238,7 @@ _rt0_64_gate_dispatcher_with_code:
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;-----------------|
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; Exception code | <- needs to be removed from stack before calling iretq
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;-----------------|
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; RIP | <- exception frame
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; RIP | <- exception frame
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; CS |
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; RFLAGS |
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; RSP |
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@@ -244,12 +246,12 @@ _rt0_64_gate_dispatcher_with_code:
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;-----------------
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cld
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; save regs and push a pointer to them
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; save regs and push a pointer to them
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save_regs
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mov rax, rsp ; rax points to saved rax
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push rax ; push pointer to saved regs
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; push pointer to exception stack frame (we have used 15 qwords for the
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; push pointer to exception stack frame (we have used 15 qwords for the
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; saved registers plus one qword for the data pushed by the gate entry
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; plus one extra qword to jump over the exception code)
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add rax, 17*8
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@@ -261,7 +263,7 @@ _rt0_64_gate_dispatcher_with_code:
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call [rsp + 18*8] ; call registered irq handler
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add rsp, 3 * 8 ; unshift the pushed arguments so rsp points to the saved regs
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add rsp, 3 * 8 ; unshift the pushed arguments so rsp points to the saved regs
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restore_regs
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add rsp, 16 ; pop handler address and exception code off the stack before returning
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@@ -271,10 +273,10 @@ _rt0_64_gate_dispatcher_with_code:
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; This dispatcher is invoked by gate entries that do not use exception codes.
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; It performs the following functions:
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; - save registers
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; - push pointer to saved regs
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; - push pointer to stack frame
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; - push pointer to saved regs
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; - push pointer to stack frame
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; - invoke handler(&frame, ®s)
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; - restore registers
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; - restore registers
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;------------------------------------------------------------------------------
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_rt0_64_gate_dispatcher_without_code:
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; This is how the stack looks like when entering this function:
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@@ -283,7 +285,7 @@ _rt0_64_gate_dispatcher_without_code:
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;------------------
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; handler address | <- pushed by gate_entry_xxx (RSP points here)
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;-----------------|
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; RIP | <- exception frame
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; RIP | <- exception frame
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; CS |
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; RFLAGS |
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; RSP |
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@@ -291,21 +293,21 @@ _rt0_64_gate_dispatcher_without_code:
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;-----------------
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cld
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; save regs and push a pointer to them
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; save regs and push a pointer to them
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save_regs
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mov rax, rsp ; rax points to saved rax
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push rax ; push pointer to saved regs
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; push pointer to exception stack frame (we have used 15 qwords for the
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; push pointer to exception stack frame (we have used 15 qwords for the
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; saved registers plus one qword for the data pushed by the gate entry)
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add rax, 16*8
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push rax
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call [rsp + 17*8] ; call registered irq handler
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add rsp, 2 * 8 ; unshift the pushed arguments so rsp points to the saved regs
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add rsp, 2 * 8 ; unshift the pushed arguments so rsp points to the saved regs
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restore_regs
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add rsp, 8 ; pop handler address off the stack before returning
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iretq
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@@ -340,13 +342,13 @@ write_string:
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; runtime functions to the kernel's own implementation without the need to
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; export/globalize any symbols. This works by first setting up a redirect table
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; (populated by a post-link step) that contains the addresses of the symbol to
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; hook and the address where calls to that symbol should be redirected.
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; hook and the address where calls to that symbol should be redirected.
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;
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; This function iterates the redirect table entries and for each entry it
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; sets up a trampoline to the dst symbol and overwrites the code in src with
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; the 14-byte long _rt0_redirect_trampoline code.
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; the 14-byte long _rt0_redirect_trampoline code.
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;
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; Note: this code modification is only possible because we are currently
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; Note: this code modification is only possible because we are currently
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; operating in supervisor mode with no memory protection enabled. Under normal
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; conditions the .text section should be flagged as read-only.
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;------------------------------------------------------------------------------
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@@ -355,7 +357,7 @@ _rt0_install_redirect_trampolines:
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mov rdx, NUM_REDIRECTS
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_rt0_install_redirect_rampolines.next:
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mov rdi, [rax] ; the symbol address to hook
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mov rdi, [rax] ; the symbol address to hook
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mov rbx, [rax+8] ; the symbol to redirect to
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; setup trampoline target and copy it to the hooked symbol
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@@ -364,15 +366,15 @@ _rt0_install_redirect_rampolines.next:
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mov rcx, 14
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rep movsb ; copy rcx bytes from rsi to rdi
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add rax, 16
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dec rdx
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add rax, 16
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dec rdx
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jnz _rt0_install_redirect_rampolines.next
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ret
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;------------------------------------------------------------------------------
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; This trampoline exploits rip-relative addressing to allow a jump to a
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; 64-bit address without the need to touch any registers. The generated
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; This trampoline exploits rip-relative addressing to allow a jump to a
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; 64-bit address without the need to touch any registers. The generated
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; code is equivalent to:
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;
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; jmp [rip+0]
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@@ -380,14 +382,14 @@ _rt0_install_redirect_rampolines.next:
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;------------------------------------------------------------------------------
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_rt0_redirect_trampoline:
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db 0xff ; the first 6 bytes encode a "jmp [rip+0]" instruction
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db 0x25
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dd 0x00
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db 0x25
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dd 0x00
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dq 0x00 ; the absolute address to jump to
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;------------------------------------------------------------------------------
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; The redirect table is placed in a dedicated section allowing us to easily
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; The redirect table is placed in a dedicated section allowing us to easily
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; find its offset in the kernel image file. As the VMA addresses of the src
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; and target symbols for the redirect are now known in advance we just reserve
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; and target symbols for the redirect are now known in advance we just reserve
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; enough space space for the src and dst addresses using the NUM_REDIRECTS
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; define which is calculated by the Makefile and passed to nasm.
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;------------------------------------------------------------------------------
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@@ -395,7 +397,7 @@ section .goredirectstbl
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_rt0_redirect_table:
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%rep NUM_REDIRECTS
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dq 0 ; src: address of the symbol we want to redirect
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dq 0 ; src: address of the symbol we want to redirect
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dq 0 ; dst: address of the symbol where calls to src are redirected to
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%endrep
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Block a user