From: Heiko Carstens Date: Fri, 7 Feb 2025 14:49:11 +0000 (+0100) Subject: s390/alternatives: Add debug functionality X-Git-Tag: v6.15-rc1~113^2~37 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f0f6db9ffe33d4f5abed2e9c522743a8c8686a0f;p=thirdparty%2Fkernel%2Flinux.git s390/alternatives: Add debug functionality 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 [/]
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 Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- diff --git a/arch/s390/boot/alternative.c b/arch/s390/boot/alternative.c index abc08d2c873d2..19ea7934b9184 100644 --- a/arch/s390/boot/alternative.c +++ b/arch/s390/boot/alternative.c @@ -1,3 +1,138 @@ // SPDX-License-Identifier: GPL-2.0 +#define boot_fmt(fmt) "alt: " fmt +#include "boot.h" + +#define a_debug boot_debug #include "../kernel/alternative.c" + +static void alt_debug_all(int type) +{ + int i; + + switch (type) { + case ALT_TYPE_FACILITY: + for (i = 0; i < ARRAY_SIZE(alt_debug.facilities); i++) + alt_debug.facilities[i] = -1UL; + break; + case ALT_TYPE_FEATURE: + for (i = 0; i < ARRAY_SIZE(alt_debug.mfeatures); i++) + alt_debug.mfeatures[i] = -1UL; + break; + case ALT_TYPE_SPEC: + alt_debug.spec = 1; + break; + } +} + +static void alt_debug_modify(int type, unsigned int nr, bool clear) +{ + switch (type) { + case ALT_TYPE_FACILITY: + if (clear) + __clear_facility(nr, alt_debug.facilities); + else + __set_facility(nr, alt_debug.facilities); + break; + case ALT_TYPE_FEATURE: + if (clear) + __clear_machine_feature(nr, alt_debug.mfeatures); + else + __set_machine_feature(nr, alt_debug.mfeatures); + break; + } +} + +static char *alt_debug_parse(int type, char *str) +{ + unsigned long val, endval; + char *endp; + bool clear; + int i; + + if (*str == ':') { + str++; + } else { + alt_debug_all(type); + return str; + } + clear = false; + if (*str == '!') { + alt_debug_all(type); + clear = true; + str++; + } + while (*str) { + val = simple_strtoull(str, &endp, 0); + if (str == endp) + break; + str = endp; + if (*str == '-') { + str++; + endval = simple_strtoull(str, &endp, 0); + if (str == endp) + break; + str = endp; + while (val <= endval) { + alt_debug_modify(type, val, clear); + val++; + } + } else { + alt_debug_modify(type, val, clear); + } + if (*str != ',') + break; + str++; + } + return str; +} + +/* + * Use debug-alternative command line parameter for debugging: + * "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 and with + * facility numbers within the range of 0-7 + * (if type 0 is ALT_TYPE_FACILITY) + * + * "debug-alternative=0:!8;1" + * -> print debug message for all alternatives with type 0, for all + * facility number, except facility 8, and in addition print all + * alternatives with type 1 + */ +void alt_debug_setup(char *str) +{ + unsigned long type; + char *endp; + int i; + + if (!str) { + alt_debug_all(ALT_TYPE_FACILITY); + alt_debug_all(ALT_TYPE_FEATURE); + alt_debug_all(ALT_TYPE_SPEC); + return; + } + while (*str) { + type = simple_strtoull(str, &endp, 0); + if (str == endp) + break; + str = endp; + switch (type) { + case ALT_TYPE_FACILITY: + case ALT_TYPE_FEATURE: + str = alt_debug_parse(type, str); + break; + case ALT_TYPE_SPEC: + alt_debug_all(ALT_TYPE_SPEC); + break; + } + if (*str != ';') + break; + str++; + } +} diff --git a/arch/s390/boot/boot.h b/arch/s390/boot/boot.h index f4af23c142cc1..bb6bd9d6d9911 100644 --- a/arch/s390/boot/boot.h +++ b/arch/s390/boot/boot.h @@ -64,6 +64,7 @@ void parse_boot_command_line(void); void verify_facilities(void); void print_missing_facilities(void); void sclp_early_setup_buffer(void); +void alt_debug_setup(char *str); void print_pgm_check_info(void); unsigned long randomize_within_range(unsigned long size, unsigned long align, unsigned long min, unsigned long max); diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c index 13316bfa589c0..86cfb16dd63da 100644 --- a/arch/s390/boot/ipl_parm.c +++ b/arch/s390/boot/ipl_parm.c @@ -296,6 +296,9 @@ void parse_boot_command_line(void) if (!strcmp(param, "facilities") && val) modify_fac_list(val); + if (!strcmp(param, "debug-alternative")) + alt_debug_setup(val); + if (!strcmp(param, "nokaslr")) __kaslr_enabled = 0; diff --git a/arch/s390/kernel/alternative.c b/arch/s390/kernel/alternative.c index 2f56649bbde87..90c0e6408992f 100644 --- a/arch/s390/kernel/alternative.c +++ b/arch/s390/kernel/alternative.c @@ -1,6 +1,11 @@ // SPDX-License-Identifier: GPL-2.0 +#ifndef pr_fmt +#define pr_fmt(fmt) "alt: " fmt +#endif + #include +#include #include #include #include @@ -8,38 +13,78 @@ #include #include +#ifndef a_debug +#define a_debug pr_debug +#endif + +#ifndef __kernel_va +#define __kernel_va(x) (void *)(x) +#endif + unsigned long __bootdata_preserved(machine_features[1]); +struct alt_debug { + unsigned long facilities[MAX_FACILITY_BIT / BITS_PER_LONG]; + unsigned long mfeatures[MAX_MFEATURE_BIT / BITS_PER_LONG]; + int spec; +}; + +static struct alt_debug __bootdata_preserved(alt_debug); + +static void alternative_dump(u8 *old, u8 *new, unsigned int len, unsigned int type, unsigned int data) +{ + char oinsn[33], ninsn[33]; + unsigned long kptr; + unsigned int pos; + + for (pos = 0; pos < len && 2 * pos < sizeof(oinsn) - 3; pos++) + hex_byte_pack(&oinsn[2 * pos], old[pos]); + oinsn[2 * pos] = 0; + for (pos = 0; pos < len && 2 * pos < sizeof(ninsn) - 3; pos++) + hex_byte_pack(&ninsn[2 * pos], new[pos]); + ninsn[2 * pos] = 0; + kptr = (unsigned long)__kernel_va(old); + a_debug("[%d/%3d] %016lx: %s -> %s\n", type, data, kptr, oinsn, ninsn); +} + void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsigned int ctx) { - u8 *instr, *replacement; + struct alt_debug *d; struct alt_instr *a; - bool replace; + bool debug, replace; + u8 *old, *new; /* * The scan order should be from start to end. A later scanned * alternative code can overwrite previously scanned alternative code. */ + d = &alt_debug; for (a = start; a < end; a++) { if (!(a->ctx & ctx)) continue; switch (a->type) { case ALT_TYPE_FACILITY: replace = test_facility(a->data); + debug = __test_facility(a->data, d->facilities); break; case ALT_TYPE_FEATURE: replace = test_machine_feature(a->data); + debug = __test_machine_feature(a->data, d->mfeatures); break; case ALT_TYPE_SPEC: replace = nobp_enabled(); + debug = d->spec; break; default: replace = false; + debug = false; } if (!replace) continue; - instr = (u8 *)&a->instr_offset + a->instr_offset; - replacement = (u8 *)&a->repl_offset + a->repl_offset; - s390_kernel_write(instr, replacement, a->instrlen); + old = (u8 *)&a->instr_offset + a->instr_offset; + new = (u8 *)&a->repl_offset + a->repl_offset; + if (debug) + alternative_dump(old, new, a->instrlen, a->type, a->data); + s390_kernel_write(old, new, a->instrlen); } } diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c index 8d0291c2b68c6..b6d3c7a6209db 100644 --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -55,6 +55,7 @@ decompressor_handled_param(nokaslr); decompressor_handled_param(cmma); decompressor_handled_param(relocate_lowcore); decompressor_handled_param(bootdebug); +__decompressor_handled_param(debug_alternative, debug-alternative); #if IS_ENABLED(CONFIG_KVM) decompressor_handled_param(prot_virt); #endif