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Kernel: fix register corruption on signal delivery

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This fixes problems with test79 and other programs.

Change-Id: I14de097a3b01114ec5dbd687ab5be9290ad13fc7
This commit is contained in:
David van Moolenbroek 2014-02-27 18:30:45 +01:00 committed by Lionel Sambuc
parent 7597f4a8fc
commit 4316052bbe
1 changed files with 33 additions and 18 deletions
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41
kernel/system/do_sigsend.c
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@ -24,6 +24,9 @@ int do_sigsend(struct proc * caller, message * m_ptr)
register struct proc *rp;
struct sigframe_sigcontext fr, *frp;
int proc_nr, r;
#if defined(__i386__)
reg_t new_fp;
#endif
if (!isokendpt(m_ptr->m_sigcalls.endpt, &proc_nr)) return EINVAL;
if (iskerneln(proc_nr)) return EPERM;
@ -35,6 +38,10 @@ int do_sigsend(struct proc * caller, message * m_ptr)
(vir_bytes)&smsg, (phys_bytes) sizeof(struct sigmsg))) != OK)
return r;
/* WARNING: the following code may be run more than once even for a single
* signal delivery. Do not change registers here. See the comment below.
*/
/* Compute the user stack pointer where sigframe will start. */
smsg.sm_stkptr = arch_get_sp(rp);
frp = (struct sigframe_sigcontext *) smsg.sm_stkptr - 1;
@ -62,7 +69,7 @@ int do_sigsend(struct proc * caller, message * m_ptr)
fr.sf_sc.sc_ss = rp->p_reg.ss;
fr.sf_fp = rp->p_reg.fp;
fr.sf_signum = smsg.sm_signo;
rp->p_reg.fp = (reg_t) &frp->sf_fp;
new_fp = (reg_t) &frp->sf_fp;
fr.sf_scpcopy = fr.sf_scp;
fr.sf_ra_sigreturn = smsg.sm_sigreturn;
fr.sf_ra= rp->p_reg.pc;
@ -108,10 +115,28 @@ int do_sigsend(struct proc * caller, message * m_ptr)
fr.sf_sc.sc_magic = SC_MAGIC;
/* Initialize the sigframe structure. */
fpu_sigcontext(rp, &fr, &fr.sf_sc);
#if defined(__arm__)
/* Copy the sigframe structure to the user's stack. */
if ((r = data_copy_vmcheck(caller, KERNEL, (vir_bytes)&fr,
m_ptr->m_sigcalls.endpt, (vir_bytes)frp,
(vir_bytes)sizeof(struct sigframe_sigcontext))) != OK)
return r;
/* WARNING: up to the statement above, the code may run multiple times, since
* copying out the frame/context may fail with VMSUSPEND the first time. For
* that reason, changes to process registers *MUST* be deferred until after
* this last copy -- otherwise, these changes will be made several times,
* possibly leading to corrupted process state.
*/
/* Reset user registers to execute the signal handler. */
rp->p_reg.sp = (reg_t) frp;
rp->p_reg.pc = (reg_t) smsg.sm_sighandler;
#if defined(__i386__)
rp->p_reg.fp = new_fp;
#elif defined(__arm__)
/* use the ARM link register to set the return address from the signal
* handler
*/
@ -125,16 +150,6 @@ int do_sigsend(struct proc * caller, message * m_ptr)
rp->p_misc_flags |= MF_CONTEXT_SET;
#endif
/* Copy the sigframe structure to the user's stack. */
if ((r = data_copy_vmcheck(caller, KERNEL, (vir_bytes)&fr,
m_ptr->m_sigcalls.endpt, (vir_bytes)frp,
(vir_bytes)sizeof(struct sigframe_sigcontext))) != OK)
return r;
/* Reset user registers to execute the signal handler. */
rp->p_reg.sp = (reg_t) frp;
rp->p_reg.pc = (reg_t) smsg.sm_sighandler;
/* Signal handler should get clean FPU. */
rp->p_misc_flags &= ~MF_FPU_INITIALIZED;