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simons |
/* windows.c: Routines to deal with register window management
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* at the C-code level.
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*
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* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
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*/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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/* Do save's until all user register windows are out of the cpu. */
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void flush_user_windows(void)
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{
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if(current->tss.uwinmask)
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flush_user_windows();
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}
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static inline void shift_window_buffer(int first_win, int last_win, struct thread_struct *tp)
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{
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int i;
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for(i = first_win; i < last_win; i++) {
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tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];
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memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window));
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}
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}
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/* Place as many of the user's current register windows
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* on the stack that we can. Even if the %sp is unaligned
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* we still copy the window there, the only case that we don't
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* succeed is if the %sp points to a bum mapping altogether.
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* setup_frame() and do_sigreturn() use this before shifting
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* the user stack around. Future instruction and hardware
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* bug workaround routines will need this functionality as
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* well.
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*/
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void synchronize_user_stack(void)
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{
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struct thread_struct *tp = ¤t->tss;
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int window;
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flush_user_windows();
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if(!tp->w_saved)
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return;
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/* Ok, there is some dirty work to do. */
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for(window = tp->w_saved - 1; window >= 0; window--) {
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unsigned long sp = tp->rwbuf_stkptrs[window];
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/* See if %sp is reasonable at all. */
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if(verify_area(VERIFY_WRITE, (char *) sp, sizeof(struct reg_window)))
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continue;
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/* Ok, let it rip. */
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memcpy((char *) sp, &tp->reg_window[window], sizeof(struct reg_window));
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shift_window_buffer(window, tp->w_saved - 1, tp);
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tp->w_saved--;
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}
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}
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/* An optimization. */
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static inline void copy_aligned_window(void *dest, const void *src)
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{
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__asm__ __volatile__("ldd [%1], %%g2\n\t"
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"ldd [%1 + 0x8], %%g4\n\t"
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"std %%g2, [%0]\n\t"
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"std %%g4, [%0 + 0x8]\n\t"
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"ldd [%1 + 0x10], %%g2\n\t"
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"ldd [%1 + 0x18], %%g4\n\t"
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"std %%g2, [%0 + 0x10]\n\t"
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"std %%g4, [%0 + 0x18]\n\t"
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"ldd [%1 + 0x20], %%g2\n\t"
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"ldd [%1 + 0x28], %%g4\n\t"
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"std %%g2, [%0 + 0x20]\n\t"
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"std %%g4, [%0 + 0x28]\n\t"
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"ldd [%1 + 0x30], %%g2\n\t"
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"ldd [%1 + 0x38], %%g4\n\t"
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"std %%g2, [%0 + 0x30]\n\t"
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"std %%g4, [%0 + 0x38]\n\t" : :
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"r" (dest), "r" (src) :
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"g2", "g3", "g4", "g5");
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}
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/* Try to push the windows in a threads window buffer to the
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* user stack. Unaligned %sp's are not allowed here.
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*/
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#define stack_is_bad(sp, rw) \
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(((sp) & 7) || verify_area(rw, (char *) (sp), sizeof(struct reg_window)))
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void try_to_clear_window_buffer(struct pt_regs *regs, int who)
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{
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struct thread_struct *tp = ¤t->tss;
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int window;
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flush_user_windows();
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for(window = 0; window < tp->w_saved; window++) {
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unsigned long sp = tp->rwbuf_stkptrs[window];
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if(stack_is_bad(sp, VERIFY_WRITE))
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do_exit(SIGILL);
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else
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copy_aligned_window((char *) sp, &tp->reg_window[window]);
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}
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tp->w_saved = 0;
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}
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