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Merge pull request #67 from achilleasa/preserve-xmm-regs-when-handling-exceptions
Preserve xmm regs when handling exceptions
This commit is contained in:
Achilleas Anagnostopoulos
GitHub
commit
170e2449d5
6
Makefile
6
Makefile
@ -32,7 +32,8 @@ GOROOT := $(shell $(GO) env GOROOT)
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GC_FLAGS ?=
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LD_FLAGS := -n -T $(BUILD_DIR)/linker.ld -static --no-ld-generated-unwind-info
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AS_FLAGS := -g -f elf64 -F dwarf -I $(BUILD_DIR)/ -I src/arch/$(ARCH)/asm/ \
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-dNUM_REDIRECTS=$(shell GOPATH=$(GOPATH) $(GO) run tools/redirects/redirects.go count)
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-dNUM_REDIRECTS=$(shell GOPATH=$(GOPATH) $(GO) run tools/redirects/redirects.go count) \
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-dWITH_RUNTIME_AVXMEMMOVE=$(shell grep -r "var useAVXmemmove" $(GOROOT)/src/runtime/ | wc -l)
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MIN_OBJCOPY_VERSION := 2.26.0
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HAVE_VALID_OBJCOPY := $(shell objcopy -V | head -1 | awk -F ' ' '{print "$(MIN_OBJCOPY_VERSION)\n" $$NF}' | sort -ct. -k1,1n -k2,2n && echo "y")
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@ -74,13 +75,14 @@ go.o:
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@# objcopy to make that symbol exportable. Since nasm does not support externs
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@# with slashes we create a global symbol alias for kernel.Kmain
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@echo "[objcopy] create kernel.Kmain alias to gopheros/kernel/kmain.Kmain"
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@echo "[objcopy] globalizing symbols {_rt0_interrupt_handlers, runtime.g0/m0/physPageSize}"
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@echo "[objcopy] globalizing symbols {_rt0_interrupt_handlers, runtime.g0/m0/physPageSize/useAVXmemmove}"
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@objcopy \
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--add-symbol kernel.Kmain=.text:0x`nm $(BUILD_DIR)/go.o | grep "kmain.Kmain$$" | cut -d' ' -f1` \
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--globalize-symbol _rt0_interrupt_handlers \
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--globalize-symbol runtime.g0 \
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--globalize-symbol runtime.m0 \
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--globalize-symbol runtime.physPageSize \
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--globalize-symbol runtime.useAVXmemmove \
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$(BUILD_DIR)/go.o $(BUILD_DIR)/go.o
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binutils_version_check:
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@ -27,6 +27,14 @@ _rt0_irq_handlers resq IDT_ENTRIES
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r0_g_ptr: resq 1
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tcb_ptr: resq 1
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; Go < 1.9 does not define runtime.useAVXmemmove; to avoid linker errors define
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; a dummy symbol so that the gate entry code can work as expected.
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%if WITH_RUNTIME_AVXMEMMOVE == 0
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runtime.useAVXmemmove resb 1
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%else
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extern runtime.useAVXmemmove
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%endif
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section .text
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;------------------------------------------------------------------------------
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@ -182,7 +190,7 @@ _rt0_64_gate_entry_%+ gate_num:
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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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%macro save_gp_regs 0
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push r15
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push r14
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push r13
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@ -200,7 +208,7 @@ _rt0_64_gate_entry_%+ gate_num:
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push rax
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%endmacro
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%macro restore_regs 0
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%macro restore_gp_regs 0
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pop rax
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pop rbx
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pop rcx
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@ -218,97 +226,163 @@ _rt0_64_gate_entry_%+ gate_num:
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pop r15
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%endmacro
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%macro save_xmm_regs 0
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sub rsp, 16*16
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movdqu [rsp+0*16], xmm0
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movdqu [rsp+1*16], xmm1
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movdqu [rsp+2*16], xmm2
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movdqu [rsp+3*16], xmm3
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movdqu [rsp+4*16], xmm4
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movdqu [rsp+5*16], xmm5
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movdqu [rsp+6*16], xmm6
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movdqu [rsp+7*16], xmm7
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movdqu [rsp+8*16], xmm8
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movdqu [rsp+9*16], xmm9
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movdqu [rsp+10*16], xmm10
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movdqu [rsp+11*16], xmm11
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movdqu [rsp+12*16], xmm12
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movdqu [rsp+13*16], xmm13
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movdqu [rsp+14*16], xmm14
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movdqu [rsp+15*16], xmm15
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%endmacro
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%macro restore_xmm_regs 0
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movdqu xmm0, [rsp+0*16]
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movdqu xmm1, [rsp+1*16]
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movdqu xmm2, [rsp+2*16]
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movdqu xmm3, [rsp+3*16]
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movdqu xmm4, [rsp+4*16]
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movdqu xmm5, [rsp+5*16]
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movdqu xmm6, [rsp+6*16]
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movdqu xmm7, [rsp+7*16]
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movdqu xmm8, [rsp+8*16]
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movdqu xmm9, [rsp+9*16]
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movdqu xmm10, [rsp+10*16]
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movdqu xmm11, [rsp+11*16]
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movdqu xmm12, [rsp+12*16]
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movdqu xmm13, [rsp+13*16]
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movdqu xmm14, [rsp+14*16]
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movdqu xmm15, [rsp+15*16]
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add rsp, 16*16
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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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; 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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; - invoke handler(code, &frame, ®s)
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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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; This is how the stack looks like when entering this function:
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; (each item is 8-bytes wide)
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; by the CPU to the stack.
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;
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;------------------
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; handler address | <- pushed by gate_entry_xxx (RSP points here)
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; This is the stack layout used by this function. Items are 8-bytes
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; wide with the exception of the xmm regs that are 16 bytes wide
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;
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; ----------------|
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; useAVXmemmove | <- original value of runtime.useAVXmemmove
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;-----------------|
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; Exception code | <- needs to be removed from stack before calling iretq
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; xmm regs (16) |
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;-----------------| <- RBP will point at the last pushed GP reg
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; gp regs (15) |
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;-----------------|
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; RIP | <- exception frame
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; handler address | <- pushed by gate_entry_xxx (RSP initially points here)
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;-----------------|
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; exception code | <- pushed by CPU (must be popped before returning)
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;-----------------|
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; RIP | <- pushed by CPU (exception frame)
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; CS |
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; RFLAGS |
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; RSP |
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; SS |
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;-----------------
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;------------------------------------------------------------------------------
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_rt0_64_gate_dispatcher_with_code:
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cld
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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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; save general-purpose regs
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save_gp_regs
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mov rbp, rsp ; rbp points to saved rax
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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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push rax
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; push exception code (located between the stack frame and the saved regs)
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sub rax, 8
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; save xmm regs as the fault handler may clobber them by calling an
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; SSE-enabled runtime function like copy (calls runtime.memmove). In
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; addition temporarily disable AVX support for runtime.memmove so we
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; don't need to also preserve the avx regs.
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save_xmm_regs
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mov rax, runtime.useAVXmemmove
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push qword [rax]
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mov byte [rax], 0
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call [rsp + 18*8] ; call registered irq handler
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; push exception handler args and call registered handler
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push qword [rbp] ; ptr to regs
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push qword [rbp+17*8] ; ptr to exception frame
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push qword [rbp+16*8] ; exception code
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call qword [rbp+15*8]
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add rsp, 3 * 8
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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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; restore xmm regs and restore AVX support for runtime.memmove
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mov rax, runtime.useAVXmemmove
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pop rbx
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mov byte [rax], bl
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restore_xmm_regs
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add rsp, 16 ; pop handler address and exception code off the stack before returning
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; restore general purpose regs
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restore_gp_regs
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; pop handler address + exception code so RSP points to the stack frame.
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add rsp, 2*8
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iretq
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;------------------------------------------------------------------------------
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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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; - invoke handler(&frame, ®s)
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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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; (each item is 8-bytes wide)
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;
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;------------------
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; handler address | <- pushed by gate_entry_xxx (RSP points here)
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; This is the stack layout used by this function. Items are 8-bytes
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; wide with the exception of the xmm regs that are 16 bytes wide
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;
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; ----------------|
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; useAVXmemmove | <- original value of runtime.useAVXmemmove
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;-----------------|
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; RIP | <- exception frame
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; xmm regs (16) |
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;-----------------| <- RBP will point at the last pushed GP reg
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; gp regs (15) |
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;-----------------|
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; handler address | <- pushed by gate_entry_xxx (RSP initially points here)
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;-----------------|
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; RIP | <- pushed by CPU (exception frame)
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; CS |
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; RFLAGS |
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; RSP |
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; SS |
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;-----------------
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;------------------------------------------------------------------------------
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_rt0_64_gate_dispatcher_without_code:
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cld
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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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; save general-purpose regs
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save_gp_regs
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mov rbp, rsp ; rbp points to saved rax
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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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; save xmm regs as the fault handler may clobber them by calling an
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; SSE-enabled runtime function like copy (calls runtime.memmove). In
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; addition temporarily disable AVX support for runtime.memmove so we
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; don't need to also preserve the avx regs.
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save_xmm_regs
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mov rax, runtime.useAVXmemmove
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push qword [rax]
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mov byte [rax], 0
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call [rsp + 17*8] ; call registered irq handler
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; push exception handler args and call registered handler
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push qword [rbp] ; ptr to regs
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push qword [rbp+16*8] ; ptr to exception frame
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call qword [rbp+15*8]
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add rsp, 2 * 8
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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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; restore xmm regs and restore AVX support for runtime.memmove
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mov rax, runtime.useAVXmemmove
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pop rbx
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mov byte [rax], bl
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restore_xmm_regs
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add rsp, 8 ; pop handler address off the stack before returning
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; restore general purpose regs
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restore_gp_regs
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; pop handler address so RSP points to the stack frame.
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add rsp, 8
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iretq
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;------------------------------------------------------------------------------
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@ -40,9 +40,10 @@ func (rb *ringBuffer) Read(p []byte) (n int, err error) {
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n = pLen
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}
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for i := 0; i < n; i, rb.rIndex = i+1, rb.rIndex+1 {
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p[i] = rb.buffer[rb.rIndex]
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}
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copy(p, rb.buffer[rb.rIndex:rb.rIndex+n])
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rb.rIndex += n
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return n, nil
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case rb.rIndex > rb.wIndex:
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// Read up to min(len(buf) - rIndex, len(p)) bytes
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n = len(rb.buffer) - rb.rIndex
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@ -50,17 +51,15 @@ func (rb *ringBuffer) Read(p []byte) (n int, err error) {
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n = pLen
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}
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for i := 0; i < n; i, rb.rIndex = i+1, rb.rIndex+1 {
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p[i] = rb.buffer[rb.rIndex]
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}
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copy(p, rb.buffer[rb.rIndex:rb.rIndex+n])
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rb.rIndex += n
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if rb.rIndex == len(rb.buffer) {
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rb.rIndex = 0
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}
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return n, nil
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default: // rIndex == wIndex
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n, err = 0, io.EOF
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return 0, io.EOF
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}
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return n, err
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}
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