c39ba09f3d
1) __riscv_float_abi_single is not in the provided preprocessor namespace. The default build sets -Werror and has -Warn implicitly. Testing something that's not defined with an #if is therefore an error. This is possibly a behavior change. If your builds ever define that AND set it to 0, this way will fail, but #if defined (foo) + #if foo is akward and probably not what you intended. 2) "csrw mtvt, t0" is not legal in at least GNU assembler (GNU Binutils) 2.35 Fortunately, riscv_encoding.h #defines a perfectly lovely value of $0x307 that's appropriate for the chips AND is compatible with more assemblers. This appears to be an extension in GNU assembler (SiFive Binutils 2.32.0-2019.08.0) 2.32 (present in bl_io_sdk, as provided by SiFive) and that's probably what's in your $PATH, but not relying on vendor extension in this case is dead easy. Two distinct problems. No, I'm not making different pull requests. ...this is a lot of words for a two line change. :-)
133 lines
4.3 KiB
ArmAsm
133 lines
4.3 KiB
ArmAsm
/* Copyright 2018 SiFive, Inc */
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/* SPDX-License-Identifier: Apache-2.0 */
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#include "riscv_encoding.h"
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/* This code executes before _start, which is contained inside the C library.
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* In embedded systems we want to ensure that _enter, which contains the first
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* code to be executed, can be loaded at a specific address. To enable this
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* feature we provide the '.text.metal.init.enter' section, which is
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* defined to have the first address being where execution should start. */
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.section .text.metal.init.enter
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.global _enter
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_enter:
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.cfi_startproc
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/* Inform the debugger that there is nowhere to backtrace past _enter. */
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.cfi_undefined ra
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/* The absolute first thing that must happen is configuring the global
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* pointer register, which must be done with relaxation disabled because
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* it's not valid to obtain the address of any symbol without GP
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* configured. The C environment might go ahead and do this again, but
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* that's safe as it's a fixed register. */
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.option push
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.option norelax
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la gp, __global_pointer$
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.option pop
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/* Disable global interrupt */
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/*clear_csr(mstatus, MSTATUS_MIE);*/
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csrci mstatus,8
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/* Set up a simple trap vector to catch anything that goes wrong early in
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* the boot process. */
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la t0, Trap_Handler_Stub
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/* enable CLIC Vectored mode */
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ori t0,t0,3
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csrw mtvec, t0
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/* enable chicken bit if core is bullet series*/
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la t0, __metal_chicken_bit
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beqz t0, 1f
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csrwi 0x7C1, 0
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1:
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/* There may be pre-initialization routines inside the MBI code that run in
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* C, so here we set up a C environment. First we set up a stack pointer,
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* which is left as a weak reference in order to allow initialization
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* routines that do not need a stack to be set up to transparently be
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* called. */
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.weak __StackTop
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la sp, __StackTop
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/* Intial the mtvt, MUST BE 64 bytes aligned*/
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.weak __Vectors
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la t0, __Vectors
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// From drivers/bl702_driver/risc-v/Core/Include/riscv_encoding.h
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csrw CSR_MTVT, t0
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#ifdef __riscv_float_abi_single
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/* deal with FP */
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/* Is F extension present? */
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csrr t0, misa
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andi t0, t0, (1 << ('F' - 'A'))
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beqz t0, 1f
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/* If so, enable it */
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li t0, MSTATUS_FS
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csrs mstatus, t0
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fssr x0
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1:
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#endif
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/* Check for an initialization routine and call it if one exists, otherwise
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* just skip over the call entirely. Note that __metal_initialize isn't
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* actually a full C function, as it doesn't end up with the .bss or .data
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* segments having been initialized. This is done to avoid putting a
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* burden on systems that can be initialized without having a C environment
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* set up. */
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call SystemInit
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/* start load code to itcm like. */
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call start_load
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/* At this point we can enter the C runtime's startup file. The arguments
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* to this function are designed to match those provided to the SEE, just
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* so we don't have to write another ABI. */
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csrr a0, mhartid
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li a1, 0
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li a2, 0
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call main
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/* If we've made it back here then there's probably something wrong. We
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* allow the METAL to register a handler here. */
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.weak __metal_after_main
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la ra, __metal_after_main
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beqz ra, 1f
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jalr ra
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1:
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/* If that handler returns then there's not a whole lot we can do. Just
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* try to make some noise. */
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la t0, 1f
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csrw mtvec, t0
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1:
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lw t1, 0(x0)
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j 1b
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.cfi_endproc
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/* For sanity's sake we set up an early trap vector that just does nothing. If
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* you end up here then there's a bug in the early boot code somewhere. */
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.weak Trap_Handler_Stub
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.section .text.metal.init.trapvec
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.align 2
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Trap_Handler_Stub:
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.cfi_startproc
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csrr t0, mcause
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csrr t1, mepc
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csrr t2, mtval
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j Trap_Handler_Stub
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.cfi_endproc
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/* The GCC port might not emit a __register_frame_info symbol, which eventually
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* results in a weak undefined reference that eventually causes crash when it
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* is dereference early in boot. We really shouldn't need to put this here,
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* but to deal with what I think is probably a bug in the linker script I'm
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* going to leave this in for now. At least it's fairly cheap :) */
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.weak __register_frame_info
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.global __register_frame_info
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.section .text.metal.init.__register_frame_info
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__register_frame_info:
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.cfi_startproc
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ret
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.cfi_endproc
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