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Revision 7ab02af428c2d312c0cf8fb0b01cc1eb21131a3d authored by Linus Torvalds on 02 February 2010, 20:37:44 UTC, committed by Linus Torvalds on 02 February 2010, 20:37:44 UTC 
Fix 'flush_old_exec()/setup_new_exec()' split
 
Commit 221af7f87b9 ("Split 'flush_old_exec' into two functions") split
the function at the point of no return - ie right where there were no
more error cases to check.  That made sense from a technical standpoint,
but when we then also combined it with the actual personality setting
going in between flush_old_exec() and setup_new_exec(), it needs to be a
bit more careful.

In particular, we need to make sure that we really flush the old
personality bits in the 'flush' stage, rather than later in the 'setup'
stage, since otherwise we might be flushing the _new_ personality state
that we're just setting up.

So this moves the flags and personality flushing (and 'flush_thread()',
which is the arch-specific function that generally resets lazy FP state
etc) of the old process into flush_old_exec(), so that it doesn't affect
any state that execve() is setting up for the new process environment.

This was reported by Michal Simek as breaking his Microblaze qemu
environment.

Reported-and-tested-by: Michal Simek <michal.simek@petalogix.com>
Cc: Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent ab65832
Raw File
tty.c 
/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright (C) 1991, 1992 Linus Torvalds
 *   Copyright 2007 rPath, Inc. - All Rights Reserved
 *   Copyright 2009 Intel Corporation; author H. Peter Anvin
 *
 *   This file is part of the Linux kernel, and is made available under
 *   the terms of the GNU General Public License version 2.
 *
 * ----------------------------------------------------------------------- */

/*
 * Very simple screen I/O
 * XXX: Probably should add very simple serial I/O?
 */

#include "boot.h"

/*
 * These functions are in .inittext so they can be used to signal
 * error during initialization.
 */

void __attribute__((section(".inittext"))) putchar(int ch)
{
	struct biosregs ireg;

	if (ch == '\n')
		putchar('\r');	/* \n -> \r\n */

	initregs(&ireg);
	ireg.bx = 0x0007;
	ireg.cx = 0x0001;
	ireg.ah = 0x0e;
	ireg.al = ch;
	intcall(0x10, &ireg, NULL);
}

void __attribute__((section(".inittext"))) puts(const char *str)
{
	while (*str)
		putchar(*str++);
}

/*
 * Read the CMOS clock through the BIOS, and return the
 * seconds in BCD.
 */

static u8 gettime(void)
{
	struct biosregs ireg, oreg;

	initregs(&ireg);
	ireg.ah = 0x02;
	intcall(0x1a, &ireg, &oreg);

	return oreg.dh;
}

/*
 * Read from the keyboard
 */
int getchar(void)
{
	struct biosregs ireg, oreg;

	initregs(&ireg);
	/* ireg.ah = 0x00; */
	intcall(0x16, &ireg, &oreg);

	return oreg.al;
}

static int kbd_pending(void)
{
	struct biosregs ireg, oreg;

	initregs(&ireg);
	ireg.ah = 0x01;
	intcall(0x16, &ireg, &oreg);

	return !(oreg.eflags & X86_EFLAGS_ZF);
}

void kbd_flush(void)
{
	for (;;) {
		if (!kbd_pending())
			break;
		getchar();
	}
}

int getchar_timeout(void)
{
	int cnt = 30;
	int t0, t1;

	t0 = gettime();

	while (cnt) {
		if (kbd_pending())
			return getchar();

		t1 = gettime();
		if (t0 != t1) {
			cnt--;
			t0 = t1;
		}
	}

	return 0;		/* Timeout! */
}
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