From 9a0b5817ad97bb718ab85322759d19a238712b47 Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Thu, 23 Mar 2006 02:59:32 -0800 Subject: [PATCH] x86: SMP alternatives Implement SMP alternatives, i.e. switching at runtime between different code versions for UP and SMP. The code can patch both SMP->UP and UP->SMP. The UP->SMP case is useful for CPU hotplug. With CONFIG_CPU_HOTPLUG enabled the code switches to UP at boot time and when the number of CPUs goes down to 1, and switches to SMP when the number of CPUs goes up to 2. Without CONFIG_CPU_HOTPLUG or on non-SMP-capable systems the code is patched once at boot time (if needed) and the tables are released afterwards. The changes in detail: * The current alternatives bits are moved to a separate file, the SMP alternatives code is added there. * The patch adds some new elf sections to the kernel: .smp_altinstructions like .altinstructions, also contains a list of alt_instr structs. .smp_altinstr_replacement like .altinstr_replacement, but also has some space to save original instruction before replaving it. .smp_locks list of pointers to lock prefixes which can be nop'ed out on UP. The first two are used to replace more complex instruction sequences such as spinlocks and semaphores. It would be possible to deal with the lock prefixes with that as well, but by handling them as special case the table sizes become much smaller. * The sections are page-aligned and padded up to page size, so they can be free if they are not needed. * Splitted the code to release init pages to a separate function and use it to release the elf sections if they are unused. Signed-off-by: Gerd Hoffmann Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/setup.c | 95 ------------------------------------------------ 1 file changed, 95 deletions(-) (limited to 'arch/i386/kernel/setup.c') diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c index ab62a9f4701e..5f58f8cb9836 100644 --- a/arch/i386/kernel/setup.c +++ b/arch/i386/kernel/setup.c @@ -1377,101 +1377,6 @@ static void __init register_memory(void) pci_mem_start, gapstart, gapsize); } -/* Use inline assembly to define this because the nops are defined - as inline assembly strings in the include files and we cannot - get them easily into strings. */ -asm("\t.data\nintelnops: " - GENERIC_NOP1 GENERIC_NOP2 GENERIC_NOP3 GENERIC_NOP4 GENERIC_NOP5 GENERIC_NOP6 - GENERIC_NOP7 GENERIC_NOP8); -asm("\t.data\nk8nops: " - K8_NOP1 K8_NOP2 K8_NOP3 K8_NOP4 K8_NOP5 K8_NOP6 - K8_NOP7 K8_NOP8); -asm("\t.data\nk7nops: " - K7_NOP1 K7_NOP2 K7_NOP3 K7_NOP4 K7_NOP5 K7_NOP6 - K7_NOP7 K7_NOP8); - -extern unsigned char intelnops[], k8nops[], k7nops[]; -static unsigned char *intel_nops[ASM_NOP_MAX+1] = { - NULL, - intelnops, - intelnops + 1, - intelnops + 1 + 2, - intelnops + 1 + 2 + 3, - intelnops + 1 + 2 + 3 + 4, - intelnops + 1 + 2 + 3 + 4 + 5, - intelnops + 1 + 2 + 3 + 4 + 5 + 6, - intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7, -}; -static unsigned char *k8_nops[ASM_NOP_MAX+1] = { - NULL, - k8nops, - k8nops + 1, - k8nops + 1 + 2, - k8nops + 1 + 2 + 3, - k8nops + 1 + 2 + 3 + 4, - k8nops + 1 + 2 + 3 + 4 + 5, - k8nops + 1 + 2 + 3 + 4 + 5 + 6, - k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, -}; -static unsigned char *k7_nops[ASM_NOP_MAX+1] = { - NULL, - k7nops, - k7nops + 1, - k7nops + 1 + 2, - k7nops + 1 + 2 + 3, - k7nops + 1 + 2 + 3 + 4, - k7nops + 1 + 2 + 3 + 4 + 5, - k7nops + 1 + 2 + 3 + 4 + 5 + 6, - k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, -}; -static struct nop { - int cpuid; - unsigned char **noptable; -} noptypes[] = { - { X86_FEATURE_K8, k8_nops }, - { X86_FEATURE_K7, k7_nops }, - { -1, NULL } -}; - -/* Replace instructions with better alternatives for this CPU type. - - This runs before SMP is initialized to avoid SMP problems with - self modifying code. This implies that assymetric systems where - APs have less capabilities than the boot processor are not handled. - Tough. Make sure you disable such features by hand. */ -void apply_alternatives(void *start, void *end) -{ - struct alt_instr *a; - int diff, i, k; - unsigned char **noptable = intel_nops; - for (i = 0; noptypes[i].cpuid >= 0; i++) { - if (boot_cpu_has(noptypes[i].cpuid)) { - noptable = noptypes[i].noptable; - break; - } - } - for (a = start; (void *)a < end; a++) { - if (!boot_cpu_has(a->cpuid)) - continue; - BUG_ON(a->replacementlen > a->instrlen); - memcpy(a->instr, a->replacement, a->replacementlen); - diff = a->instrlen - a->replacementlen; - /* Pad the rest with nops */ - for (i = a->replacementlen; diff > 0; diff -= k, i += k) { - k = diff; - if (k > ASM_NOP_MAX) - k = ASM_NOP_MAX; - memcpy(a->instr + i, noptable[k], k); - } - } -} - -void __init alternative_instructions(void) -{ - extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; - apply_alternatives(__alt_instructions, __alt_instructions_end); -} - static char * __init machine_specific_memory_setup(void); #ifdef CONFIG_MCA -- cgit v1.2.2 From 99b7de33477882b86d54ce8ecbf90147f9d106d7 Mon Sep 17 00:00:00 2001 From: Stas Sergeev Date: Thu, 23 Mar 2006 02:59:41 -0800 Subject: [PATCH] x86: early printk handling fixes The history is that -mm kernels do not work for me for a few months already. The things started from crashing somewhere after starting init, and for the last month - no boot at all, just "Uncompressing... OK, booting kernel", and silence. Early console didn't work too. With the latest releases this degraded into an infinite stream of the "Unknown interrupt or fault" messages. So today my patience ran out and I started to think how can I collect at least some info for the bug-report. Attached is the patch that allows to gather some valueable debug info on the problem by making an early console more useable. I can't properly test the patch, as the kernel still doesn't boot, so I'll explain it in details in a hope someone else can justify the intrusive changes. arch_hooks.h: added prototypes for setup_early_printk() and early_printk(). setup.c: killed wrong setup_early_printk() prototype. Moved setup_early_printk() a bit earlier, as it was not "early enough" to cover the bug I was fighting with. early_printk.c: made it to start printing from the bottom of the screen, otherwise the messages interfere with the ones of the boot-loader, so you can't read them. Signed-off-by: Stas Sergeev Cc: Andi Kleen Cc: Zwane Mwaikambo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/setup.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) (limited to 'arch/i386/kernel/setup.c') diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c index 5f58f8cb9836..2d8782960f41 100644 --- a/arch/i386/kernel/setup.c +++ b/arch/i386/kernel/setup.c @@ -1459,6 +1459,16 @@ void __init setup_arch(char **cmdline_p) parse_cmdline_early(cmdline_p); +#ifdef CONFIG_EARLY_PRINTK + { + char *s = strstr(*cmdline_p, "earlyprintk="); + if (s) { + setup_early_printk(strchr(s, '=') + 1); + printk("early console enabled\n"); + } + } +#endif + max_low_pfn = setup_memory(); /* @@ -1483,19 +1493,6 @@ void __init setup_arch(char **cmdline_p) * NOTE: at this point the bootmem allocator is fully available. */ -#ifdef CONFIG_EARLY_PRINTK - { - char *s = strstr(*cmdline_p, "earlyprintk="); - if (s) { - extern void setup_early_printk(char *); - - setup_early_printk(strchr(s, '=') + 1); - printk("early console enabled\n"); - } - } -#endif - - dmi_scan_machine(); #ifdef CONFIG_X86_GENERICARCH -- cgit v1.2.2