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f0f6db9ffe
Similar to x86 and loongarch add a "debug-alternative" command line parameter, which allows for alternative debugging. The parameter itself comes with architecture specific semantics: "debug-alternative" -> print debug message for every single alternative "debug-alternative=0;2" -> print debug message for all alternatives with type 0 and 2 "debug-alternative=0:0-7" -> print debug message for all alternatives with type 0 which have a facility number within the range of 0-7 "debug-alternative=0:!8;1" -> print debug message for all alternatives with type 0, for all facility numbers, except facility 8, and in addition print all alternatives with type 1 A defconfig build currently results in a kernel with more than 20.000 alternatives, where the majority is for the niai alternative (spinlocks), and the relocated lowcore alternative. The following kernel command like options limit alternative debug output, and enable dynamic debug messages: debug-alternative=0:!49;1:!0 earlyprintk bootdebug ignore_loglevel loglevel=8 dyndbg="file alternative.c +p" This results in output like this: alt: [0/ 11] 0000021b9ce8680c: c0f400000089 -> c00400000000 alt: [0/ 64] 0000021b9ce87e60: c0f400000043 -> c00400000000 alt: [0/133] 0000021b9ce88c56: c0f400000027 -> c00400000000 alt: [0/ 74] 0000021b9ce89410: c0f40000002a -> c00400000000 alt: [0/ 40] 0000021b9dc3720a: 47000000 -> b280d398 alt: [0/193] 0000021b9dc37306: 47000000 -> b201d2b0 alt: [0/193] 0000021b9dc37354: c00400000000 -> d20720c0d2b0 alt: [1/ 5] 0000038d720d7bf2: c0f400000016 -> c00400000000 With [<alternative type>/<alternative data>] <address> oldcode -> newcode Alternative data depends on the alternative type: for type 0 (ALT_TYPE_FACILITY) data is the facility. For type 1 (ALT_TYPE_FEATURE) data is the corresponding machine feature. Acked-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef pr_fmt
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#define pr_fmt(fmt) "alt: " fmt
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#endif
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#include <linux/uaccess.h>
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#include <linux/printk.h>
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#include <asm/nospec-branch.h>
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#include <asm/abs_lowcore.h>
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#include <asm/alternative.h>
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#include <asm/facility.h>
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#include <asm/sections.h>
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#include <asm/machine.h>
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#ifndef a_debug
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#define a_debug pr_debug
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#endif
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#ifndef __kernel_va
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#define __kernel_va(x) (void *)(x)
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#endif
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unsigned long __bootdata_preserved(machine_features[1]);
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struct alt_debug {
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unsigned long facilities[MAX_FACILITY_BIT / BITS_PER_LONG];
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unsigned long mfeatures[MAX_MFEATURE_BIT / BITS_PER_LONG];
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int spec;
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};
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static struct alt_debug __bootdata_preserved(alt_debug);
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static void alternative_dump(u8 *old, u8 *new, unsigned int len, unsigned int type, unsigned int data)
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{
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char oinsn[33], ninsn[33];
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unsigned long kptr;
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unsigned int pos;
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for (pos = 0; pos < len && 2 * pos < sizeof(oinsn) - 3; pos++)
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hex_byte_pack(&oinsn[2 * pos], old[pos]);
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oinsn[2 * pos] = 0;
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for (pos = 0; pos < len && 2 * pos < sizeof(ninsn) - 3; pos++)
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hex_byte_pack(&ninsn[2 * pos], new[pos]);
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ninsn[2 * pos] = 0;
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kptr = (unsigned long)__kernel_va(old);
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a_debug("[%d/%3d] %016lx: %s -> %s\n", type, data, kptr, oinsn, ninsn);
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}
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void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsigned int ctx)
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{
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struct alt_debug *d;
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struct alt_instr *a;
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bool debug, replace;
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u8 *old, *new;
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/*
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* The scan order should be from start to end. A later scanned
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* alternative code can overwrite previously scanned alternative code.
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*/
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d = &alt_debug;
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for (a = start; a < end; a++) {
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if (!(a->ctx & ctx))
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continue;
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switch (a->type) {
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case ALT_TYPE_FACILITY:
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replace = test_facility(a->data);
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debug = __test_facility(a->data, d->facilities);
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break;
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case ALT_TYPE_FEATURE:
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replace = test_machine_feature(a->data);
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debug = __test_machine_feature(a->data, d->mfeatures);
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break;
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case ALT_TYPE_SPEC:
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replace = nobp_enabled();
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debug = d->spec;
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break;
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default:
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replace = false;
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debug = false;
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}
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if (!replace)
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continue;
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old = (u8 *)&a->instr_offset + a->instr_offset;
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new = (u8 *)&a->repl_offset + a->repl_offset;
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if (debug)
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alternative_dump(old, new, a->instrlen, a->type, a->data);
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s390_kernel_write(old, new, a->instrlen);
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}
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}
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