| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
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| 2 | /* |
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| 3 | * kmsg dumper that ensures the OPAL console fully flushes panic messages |
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| 4 | * |
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| 5 | * Author: Russell Currey <ruscur@russell.cc> |
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| 6 | * |
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| 7 | * Copyright 2015 IBM Corporation. |
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| 8 | */ |
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| 9 | |
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| 10 | #include <linux/kmsg_dump.h> |
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| 11 | |
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| 12 | #include <asm/opal.h> |
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| 13 | #include <asm/opal-api.h> |
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| 14 | |
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| 15 | /* |
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| 16 | * Console output is controlled by OPAL firmware. The kernel regularly calls |
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| 17 | * OPAL_POLL_EVENTS, which flushes some console output. In a panic state, |
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| 18 | * however, the kernel no longer calls OPAL_POLL_EVENTS and the panic message |
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| 19 | * may not be completely printed. This function does not actually dump the |
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| 20 | * message, it just ensures that OPAL completely flushes the console buffer. |
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| 21 | */ |
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| 22 | static void kmsg_dump_opal_console_flush(struct kmsg_dumper *dumper, |
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| 23 | struct kmsg_dump_detail *detail) |
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| 24 | { |
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| 25 | /* |
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| 26 | * Outside of a panic context the pollers will continue to run, |
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| 27 | * so we don't need to do any special flushing. |
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| 28 | */ |
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| 29 | if (detail->reason != KMSG_DUMP_PANIC) |
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| 30 | return; |
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| 31 | |
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| 32 | opal_flush_console(0); |
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| 33 | } |
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| 34 | |
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| 35 | static struct kmsg_dumper opal_kmsg_dumper = { |
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| 36 | .dump = kmsg_dump_opal_console_flush |
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| 37 | }; |
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| 38 | |
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| 39 | void __init opal_kmsg_init(void) |
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| 40 | { |
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| 41 | int rc; |
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| 42 | |
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| 43 | /* Add our dumper to the list */ |
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| 44 | rc = kmsg_dump_register(dumper: &opal_kmsg_dumper); |
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| 45 | if (rc != 0) |
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| 46 | pr_err("opal: kmsg_dump_register failed; returned %d\n" , rc); |
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| 47 | } |
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| 48 | |
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