Warner Losh
75cbdbc983
Add support for aarch64. exec.c and ldscript are copied from the EFI version with #ifdefs for the differences. Once complete, I'll refactor them. host_syscall.S implements a generic system call. tramp.S is a first attempt to create a tramoline that we can use to jump to the aarch64 kernel. Add aarch64-specific startup and stat files as well. exec.c tweaked slightly to avoid bringing in bi_load(), which will come in later. Includes tweaks to stat due to name differences between names on different Linux architectures. Sponsored by: Netflix
68 lines
2.0 KiB
ArmAsm
68 lines
2.0 KiB
ArmAsm
/*
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* Copyright (c) 2022, Netflix, Inc.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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/*
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* This is the trampoline that starts the FreeBSD kernel. Since the Linux kernel
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* calls this routine with no args, and has a different environment than the boot
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* loader provides and that the kernel expects, this code is responsible for setting
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* all that up and calling the normal kernel entry point. It's analogous ot the
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* "purgatory" code in the linux kernel. Details about these operations are
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* contained in comments below. On aarch64, the kernel will start all the APs so
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* we don't have to worry about them here.
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*/
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/*
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* Keep in sync with exec.c. Kexec starts aarch64_tramp w/o any
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* parameters, so store them here.
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*
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* struct trampoline_data {
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* uint64_t entry; // 0 (PA where kernel loaded)
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* uint64_t modulep; // 8 module metadata
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* };
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*
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* The aarch64 _start routine assumes:
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* MMU on with an identity map, or off
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* D-Cache: off
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* I-Cache: on or off
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* We are loaded at a 2MiB aligned address
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* Module data (modulep) pointer in x0
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*
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* Unlike EFI, we don't support copying the staging area. We tell Linunx to land
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* the kernel in its final location with the needed alignment, etc.
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*
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* This trampoline installs sets up the arguments the kernel expects, flushes
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* the cache lines and jumps to the kernel _start address. We pass the modulep
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* pointer in x0, as _start expects.
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*/
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.text
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.globl aarch64_tramp
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aarch64_tramp:
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b 1f /* skip over our saved args */
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.p2align 3
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trampoline_data:
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#define TRAMP_ENTRY 0
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#define TRAMP_MODULEP 8
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#define TRAMP_TOTAL 16
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.space TRAMP_TOTAL
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#define TMPSTACKSIZE 48 /* 16 bytes for args +8 for pushq/popfq + 24 spare */
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1:
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adr x2, trampoline_data
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ldr x1, [x2, #TRAMP_ENTRY]
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ldr x0, [x2, #TRAMP_MODULEP]
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br x1
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.p2align 4
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.space TMPSTACKSIZE
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aarch64_tramp_end: /* padding doubles as stack */
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.data
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.globl aarch64_tramp_size
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aarch64_tramp_size:
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.long aarch64_tramp_end-aarch64_tramp
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.globl aarch64_tramp_data_offset
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aarch64_tramp_data_offset:
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.long trampoline_data-aarch64_tramp
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