cregit-Linux how code gets into the kernel

Release 4.11 arch/arm/kernel/xscale-cp0.c

Directory: arch/arm/kernel
/*
 * linux/arch/arm/kernel/xscale-cp0.c
 *
 * XScale DSP and iWMMXt coprocessor context switching and handling
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/io.h>
#include <asm/thread_notify.h>
#include <asm/cputype.h>

asm("   .arch armv5te\n");


static inline void dsp_save_state(u32 *state) { __asm__ __volatile__ ( "mrrc p0, 0, %0, %1, c0\n" : "=r" (state[0]), "=r" (state[1])); }

Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek14100.00%1100.00%
Total14100.00%1100.00%


static inline void dsp_load_state(u32 *state) { __asm__ __volatile__ ( "mcrr p0, 0, %0, %1, c0\n" : : "r" (state[0]), "r" (state[1])); }

Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek14100.00%1100.00%
Total14100.00%1100.00%


static int dsp_do(struct notifier_block *self, unsigned long cmd, void *t) { struct thread_info *thread = t; switch (cmd) { case THREAD_NOTIFY_FLUSH: thread->cpu_context.extra[0] = 0; thread->cpu_context.extra[1] = 0; break; case THREAD_NOTIFY_SWITCH: dsp_save_state(current_thread_info()->cpu_context.extra); dsp_load_state(thread->cpu_context.extra); break; } return NOTIFY_DONE; }

Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek84100.00%1100.00%
Total84100.00%1100.00%

static struct notifier_block dsp_notifier_block = { .notifier_call = dsp_do, }; #ifdef CONFIG_IWMMXT
static int iwmmxt_do(struct notifier_block *self, unsigned long cmd, void *t) { struct thread_info *thread = t; switch (cmd) { case THREAD_NOTIFY_FLUSH: /* * flush_thread() zeroes thread->fpstate, so no need * to do anything here. * * FALLTHROUGH: Ensure we don't try to overwrite our newly * initialised state information on the first fault. */ case THREAD_NOTIFY_EXIT: iwmmxt_task_release(thread); break; case THREAD_NOTIFY_SWITCH: iwmmxt_task_switch(thread); break; } return NOTIFY_DONE; }

Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek5698.25%150.00%
Russell King11.75%150.00%
Total57100.00%2100.00%

static struct notifier_block iwmmxt_notifier_block = { .notifier_call = iwmmxt_do, }; #endif
static u32 __init xscale_cp_access_read(void) { u32 value; __asm__ __volatile__ ( "mrc p15, 0, %0, c15, c1, 0\n\t" : "=r" (value)); return value; }

Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek18100.00%1100.00%
Total18100.00%1100.00%


static void __init xscale_cp_access_write(u32 value) { u32 temp; __asm__ __volatile__ ( "mcr p15, 0, %1, c15, c1, 0\n\t" "mrc p15, 0, %0, c15, c1, 0\n\t" "mov %0, %0\n\t" "sub pc, pc, #4\n\t" : "=r" (temp) : "r" (value)); }

Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek16100.00%1100.00%
Total16100.00%1100.00%

/* * Detect whether we have a MAC coprocessor (40 bit register) or an * iWMMXt coprocessor (64 bit registers) by loading 00000100:00000000 * into a coprocessor register and reading it back, and checking * whether the upper word survived intact. */
static int __init cpu_has_iwmmxt(void) { u32 lo; u32 hi; /* * This sequence is interpreted by the DSP coprocessor as: * mar acc0, %2, %3 * mra %0, %1, acc0 * * And by the iWMMXt coprocessor as: * tmcrr wR0, %2, %3 * tmrrc %0, %1, wR0 */ __asm__ __volatile__ ( "mcrr p0, 0, %2, %3, c0\n" "mrrc p0, 0, %0, %1, c0\n" : "=r" (lo), "=r" (hi) : "r" (0), "r" (0x100)); return !!hi; }

Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek24100.00%1100.00%
Total24100.00%1100.00%

/* * If we detect that the CPU has iWMMXt (and CONFIG_IWMMXT=y), we * disable CP0/CP1 on boot, and let call_fpe() and the iWMMXt lazy * switch code handle iWMMXt context switching. If on the other * hand the CPU has a DSP coprocessor, we keep access to CP0 enabled * all the time, and save/restore acc0 on context switch in non-lazy * fashion. */
static int __init xscale_cp0_init(void) { u32 cp_access; /* do not attempt to probe iwmmxt on non-xscale family CPUs */ if (!cpu_is_xscale_family()) return 0; cp_access = xscale_cp_access_read() & ~3; xscale_cp_access_write(cp_access | 1); if (cpu_has_iwmmxt()) { #ifndef CONFIG_IWMMXT pr_warn("CAUTION: XScale iWMMXt coprocessor detected, but kernel support is missing.\n"); #else pr_info("XScale iWMMXt coprocessor detected.\n"); elf_hwcap |= HWCAP_IWMMXT; thread_register_notifier(&iwmmxt_notifier_block); #endif } else { pr_info("XScale DSP coprocessor detected.\n"); thread_register_notifier(&dsp_notifier_block); cp_access |= 1; } xscale_cp_access_write(cp_access); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek8385.57%133.33%
Arnd Bergmann1010.31%133.33%
Russell King44.12%133.33%
Total97100.00%3100.00%

late_initcall(xscale_cp0_init);

Overall Contributors

PersonTokensPropCommitsCommitProp
Lennert Buytenhek36594.56%120.00%
Arnd Bergmann143.63%120.00%
Russell King71.81%360.00%
Total386100.00%5100.00%
Directory: arch/arm/kernel
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with cregit.