Date: Sat, 29 Jul 2006 12:57:52 -0700 From: "Kip Macy" <kip.macy@gmail.com> To: "Tijl Coosemans" <tijl@ulyssis.org> Cc: freebsd-hackers@freebsd.org Subject: Re: i386 page fault clobbers error code in trap frame Message-ID: <b1fa29170607291257h43592826j75513b465074f115@mail.gmail.com> In-Reply-To: <200607292110.37733.tijl@ulyssis.org> References: <200607292110.37733.tijl@ulyssis.org>
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Looking at siginfo it isn't clear that there is a "right way" to
provide SIGSEGV, eva, and the error code.
_fault._trapno should contain the machine's error code and si_signo
should contain SIGSEGV, and si_addr contains the faulting pc. Maybe
one could abuse si_code to contain eva. Sorry for asking a question
that has already been answered but where is eva being put currently?
typedef struct __siginfo {
int si_signo; /* signal number */
int si_errno; /* errno association */
/*
* Cause of signal, one of the SI_ macros or signal-specific
* values, i.e. one of the FPE_... values for SIGFPE. This
* value is equivalent to the second argument to an old-style
* FreeBSD signal handler.
*/
int si_code; /* signal code */
__pid_t si_pid; /* sending process */
__uid_t si_uid; /* sender's ruid */
int si_status; /* exit value */
void *si_addr; /* faulting instruction */
union sigval si_value; /* signal value */
union {
struct {
int _trapno;/* machine specific trap code */
} _fault;
/* .... */
On 7/29/06, Tijl Coosemans <tijl@ulyssis.org> wrote:
> I'm refering to the following two lines in sys/i386/i386/trap.c
>
> /* kludge to pass faulting virtual address to sendsig */
> frame->tf_err = eva;
>
> Isn't there some other way to do this? Wouldn't the address still be
> available in %cr2 inside sendsig? Or could there have been other page
> faults by then?
>
> The reason I'm asking this is that Wine wants to know the error code in
> case of a page fault (the No eXec bit (AMD) and the read/write bit
> specifically).
>
>
>
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