added new metal sdk

1 files changed, 246 insertions, 0 deletions

diff --git a/code/fe310/gloss/crt0.S b/code/fe310/gloss/crt0.S
new file mode 100644
index 0000000..920ee4b
--- /dev/null
+++ b/code/fe310/gloss/crt0.S
@@ -0,0 +1,246 @@
+/* Copyright (c) 2017-2018  SiFive Inc. All rights reserved.
+
+   This copyrighted material is made available to anyone wishing to use,
+   modify, copy, or redistribute it subject to the terms and conditions
+   of the FreeBSD License.   This program is distributed in the hope that
+   it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
+   including the implied warranties of MERCHANTABILITY or FITNESS FOR
+   A PARTICULAR PURPOSE.  A copy of this license is available at
+   http://www.opensource.org/licenses.
+*/
+
+/* crt0.S: Entry point for RISC-V METAL programs. */
+
+.section .text.libgloss.start
+.global _start
+.type   _start, @function
+
+  /* _start is defined by the METAL to have been called with the following
+   * arguments:
+   *   a0: the hart ID of the currently executing hart.  Harts can start at
+   *       any arbitrary point, it's the C library's job to ensure the code is
+   *       safe.
+   *   a1: a pointer to a description of the machine on which this code is
+   *       currently executing.  This is probably 0 on an embedded system
+   *       because they tend to not be dynamically portable.  As such, newlib
+   *       ignores this argument.
+   *   a2: a pointer to a function that must be run after the envirnoment has
+   *       been initialized, but before user code can be expected to be run.
+   *       If this is 0 then there is no function to be run. */
+_start:
+.cfi_startproc
+.cfi_undefined ra
+
+  /* This is a bit funky: it's not usually sane for _start to return, but in
+   * this case we actually want to in order to signal an error to the METAL. */
+  mv s0, ra
+
+  /* Before doing anything we must initialize the global pointer, as we cannot
+   * safely perform any access that may be relaxed without GP being set.  This
+   * is done with relaxation disabled to avoid relaxing the address calculation
+   * to just "addi gp, gp, 0". */
+.option push
+.option norelax
+  la gp, __global_pointer$
+.option pop
+
+  /* The METAL is designed for a bare-metal environment and therefor is expected
+   * to define its own stack pointer.  We also align the stack pointer here
+   * because the only RISC-V ABI that's currently defined mandates 16-byte
+   * stack alignment. */
+  la sp, _sp
+
+  /* Increment by hartid number of stack sizes */
+  li t0, 0
+  la t1, __stack_size
+1:
+  beq t0, a0, 1f
+  add sp, sp, t1
+  addi t0, t0, 1
+  j 1b
+1:
+  andi sp, sp, -16
+
+  /* If we're not hart 0, skip the initialization work */
+  la t0, __metal_boot_hart
+  bne a0, t0, _skip_init
+
+  /* Embedded systems frequently require relocating the data segment before C
+   * code can be run -- for example, the data segment may exist in flash upon
+   * boot and then need to get relocated into a non-persistant writable memory
+   * before C code can execute.  If this is the case we do so here.  This step
+   * is optional: if the METAL provides an environment in which this relocation
+   * is not necessary then it must simply set metal_segment_data_source_start to
+   * be equal to metal_segment_data_target_start. */
+  la t0, metal_segment_data_source_start
+  la t1, metal_segment_data_target_start
+  la t2, metal_segment_data_target_end
+
+  beq t0, t1, 2f
+  bge t1, t2, 2f
+
+1:
+#if __riscv_xlen == 32
+  lw   a0, 0(t0)
+  addi t0, t0, 4
+  sw   a0, 0(t1)
+  addi t1, t1, 4
+  blt  t1, t2, 1b
+#else
+  ld   a0, 0(t0)
+  addi t0, t0, 8
+  sd   a0, 0(t1)
+  addi t1, t1, 8
+  blt  t1, t2, 1b
+#endif
+2:
+
+  /* Copy the ITIM section */
+  la t0, metal_segment_itim_source_start
+  la t1, metal_segment_itim_target_start
+  la t2, metal_segment_itim_target_end
+
+  beq t0, t1, 2f
+  bge t1, t2, 2f
+
+1:
+#if __riscv_xlen == 32
+  lw   a0, 0(t0)
+  addi t0, t0, 4
+  sw   a0, 0(t1)
+  addi t1, t1, 4
+  blt  t1, t2, 1b
+#else
+  ld   a0, 0(t0)
+  addi t0, t0, 8
+  sd   a0, 0(t1)
+  addi t1, t1, 8
+  blt  t1, t2, 1b
+#endif
+2:
+
+  /* Fence all subsequent instruction fetches until after the ITIM writes
+     complete */
+  fence.i
+
+  /* Zero the BSS segment. */
+  la t1, metal_segment_bss_target_start
+  la t2, metal_segment_bss_target_end
+
+  bge t1, t2, 2f
+
+1:
+#if __riscv_xlen == 32
+  sw   x0, 0(t1)
+  addi t1, t1, 4
+  blt  t1, t2, 1b
+#else
+  sd   x0, 0(t1)
+  addi t1, t1, 8
+  blt  t1, t2, 1b
+#endif
+2:
+
+  /* At this point we're in an environment that can execute C code.  The first
+   * thing to do is to make the callback to the parent environment if it's been
+   * requested to do so. */
+  beqz a2, 1f
+  jalr a2
+1:
+
+  /* The RISC-V port only uses new-style constructors and destructors. */
+  la a0, __libc_fini_array
+  call atexit
+  call __libc_init_array
+
+_skip_init:
+
+  /* Synchronize harts so that secondary harts wait until hart 0 finishes
+     initializing */
+  call __metal_synchronize_harts
+
+  /* Check RISC-V isa and enable FS bits if Floating Point architecture. */
+  csrr a5, misa
+  li   a4, 0x10028
+  and  a5, a5, a4
+  beqz a5, 1f
+  csrr a5, mstatus
+  lui  a4, 0x2
+  or   a5, a5, a4
+  csrw mstatus, a5
+  csrwi fcsr, 0
+1:
+
+  /* This is a C runtime, so main() is defined to have some arguments.  Since
+   * there's nothing sane the METAL can pass we don't bother with that but
+   * instead just setup as close to a NOP as we can. */
+  li a0, 1     /* argc=1 */
+  la a1, argv  /* argv = {"libgloss", NULL} */
+  la a2, envp  /* envp = {NULL} */
+  call secondary_main
+
+  /* Call exit to handle libc's cleanup routines.  Under normal contains this
+   * shouldn't even get called, but I'm still not using a tail call here
+   * because returning to the METAL is the right thing to do in pathological
+   * situations. */
+  call exit
+
+  /* And here's where we return.  Again, it's a bit odd but the METAL defines
+   * this as a bad idea (ie, as opposed to leaving it undefined) and at this
+   * point it's really the only thing left to do. */
+  mv ra, s0
+  ret
+
+.cfi_endproc
+
+/* RISC-V systems always use __libc_{init,fini}_array, but for compatibility we
+ * define _{init,fini} to do nothing. */
+.global _init
+.type   _init, @function
+.global _fini
+.type   _fini, @function
+_init:
+_fini:
+  ret
+.size _init, .-_init
+.size _fini, .-_fini
+
+/* By default, secondary_main will cause secondary harts to spin forever.
+ * Users can redefine secondary_main themselves to run code on secondary harts */
+.weak   secondary_main
+.global secondary_main
+.type   secondary_main, @function
+
+secondary_main:
+  addi sp, sp, -16
+#if __riscv_xlen == 32
+  sw ra, 4(sp)
+#else
+  sd ra, 8(sp)
+#endif
+  csrr t0, mhartid
+  la t1, __metal_boot_hart
+  beq t0, t1, 2f
+1:
+  wfi
+  j 1b
+2:
+  call main
+#if __riscv_xlen == 32
+  lw ra, 4(sp)
+#else
+  ld ra, 8(sp)
+#endif
+  addi sp, sp, 16
+  ret
+
+/* This shim allows main() to be passed a set of arguments that can satisfy the
+ * requirements of the C API. */
+.section .rodata.libgloss.start
+argv:
+.dc.a name
+envp:
+.dc.a 0
+name:
+.asciz "libgloss"
+