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Restore user-owned bits from PSW after a signal handler, instead of

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copying complete PSW after signal handler.

This fixes a psw corruption bug reported by Jens de Smit <jst260@few.vu.nl>.
This commit is contained in:
Ben Gras 2007-05-08 15:43:00 +00:00
parent 56a68dc32b
commit b00f287449
2 changed files with 17 additions and 10 deletions
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22
include/ibm/cpu.h
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@ -1,15 +1,19 @@
#ifndef _IBM_CPU_H
#define _IBM_CPU_H 1
#define X86_FLAG_C (1L << 0) /* Carry */
#define X86_FLAG_P (1L << 2) /* Parity */
#define X86_FLAG_A (1L << 4) /* Aux. carry */
#define X86_FLAG_Z (1L << 6) /* Zero */
#define X86_FLAG_S (1L << 7) /* Sign */
#define X86_FLAG_C (1L << 0) /* S Carry */
#define X86_FLAG_P (1L << 2) /* S Parity */
#define X86_FLAG_A (1L << 4) /* S Aux. carry */
#define X86_FLAG_Z (1L << 6) /* S Zero */
#define X86_FLAG_S (1L << 7) /* S Sign */
#define X86_FLAG_T (1L << 8) /* Trap */
#define X86_FLAG_I (1L << 9) /* Interrupt */
#define X86_FLAG_D (1L << 10) /* Direction */
#define X86_FLAG_O (1L << 11) /* Overflow */
#define X86_FLAG_T (1L << 8) /* X Trap */
#define X86_FLAG_I (1L << 9) /* X Interrupt */
#define X86_FLAG_D (1L << 10) /* C Direction */
#define X86_FLAG_O (1L << 11) /* S Overflow */
/* User flags are S (Status) and C (Control) flags. */
#define X86_FLAGS_USER (X86_FLAG_C | X86_FLAG_P | X86_FLAG_A | X86_FLAG_Z | \
X86_FLAG_S | X86_FLAG_D | X86_FLAG_O)
#endif

5
kernel/system/do_sigreturn.c
View file

@ -10,6 +10,7 @@
#include "../system.h"
#include <string.h>
#include <signal.h>
#include <ibm/cpu.h>
#include <sys/sigcontext.h>
#if USE_SIGRETURN
@ -38,7 +39,9 @@ message *m_ptr; /* pointer to request message */
if (src_phys == 0) return(EFAULT);
phys_copy(src_phys, vir2phys(&sc), (phys_bytes) sizeof(struct sigcontext));
sc.sc_psw = rp->p_reg.psw;
/* Restore user bits of psw from sc, maintain system bits from proc. */
sc.sc_psw = (sc.sc_psw & X86_FLAGS_USER) |
(rp->p_reg.psw & ~X86_FLAGS_USER);
#if (_MINIX_CHIP == _CHIP_INTEL)
/* Don't panic kernel if user gave bad selectors. */