[PATCH v2] tcg: Use correct trap number for page faults on *BSD systems

[PATCH v2] tcg: Use correct trap number for page faults on *BSD systems

[Warner Losh]

The trap number for a page fault on BSD systems is T_PAGEFLT not 0xe. 0xe is
used by Linux and represents the intel hardware trap vector. The BSD kernels,
however, translate this to T_PAGEFLT in their Xpage, Xtrap0e, Xtrap14, etc fault
handlers. This is true for i386 and x86_64, though the name of the trap hanlder
can very on the flavor of BSD. As far as I can tell, Linux doesn't provide a
define for this value. Invent a new one (PAGE_FAULT_TRAP) and use it instead to
avoid uglier ifdefs.

Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Signed-off-by: Juergen Lock <nox@FreeBSD.org>
[ Rework to avoid ifdefs and expand it to i386 ]
Signed-off-by: Warner Losh <imp@bsdimp.com>
---
 accel/tcg/user-exec.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 0d8cc27b21..959fec1257 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -260,6 +260,7 @@ void *probe_access(CPUArchState *env, target_ulong addr, int size,
 #define TRAP_sig(context)    ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
 #define ERROR_sig(context)   ((context)->uc_mcontext.__gregs[_REG_ERR])
 #define MASK_sig(context)    ((context)->uc_sigmask)
+#define PAGE_FAULT_TRAP      T_PAGEFLT
 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 #include <ucontext.h>
 
@@ -267,16 +268,19 @@ void *probe_access(CPUArchState *env, target_ulong addr, int size,
 #define TRAP_sig(context)    ((context)->uc_mcontext.mc_trapno)
 #define ERROR_sig(context)   ((context)->uc_mcontext.mc_err)
 #define MASK_sig(context)    ((context)->uc_sigmask)
+#define PAGE_FAULT_TRAP      T_PAGEFLT
 #elif defined(__OpenBSD__)
 #define EIP_sig(context)     ((context)->sc_eip)
 #define TRAP_sig(context)    ((context)->sc_trapno)
 #define ERROR_sig(context)   ((context)->sc_err)
 #define MASK_sig(context)    ((context)->sc_mask)
+#define PAGE_FAULT_TRAP      T_PAGEFLT
 #else
 #define EIP_sig(context)     ((context)->uc_mcontext.gregs[REG_EIP])
 #define TRAP_sig(context)    ((context)->uc_mcontext.gregs[REG_TRAPNO])
 #define ERROR_sig(context)   ((context)->uc_mcontext.gregs[REG_ERR])
 #define MASK_sig(context)    ((context)->uc_sigmask)
+#define PAGE_FAULT_TRAP      0xe
 #endif
 
 int cpu_signal_handler(int host_signum, void *pinfo,
@@ -302,7 +306,8 @@ int cpu_signal_handler(int host_signum, void *pinfo,
     pc = EIP_sig(uc);
     trapno = TRAP_sig(uc);
     return handle_cpu_signal(pc, info,
-                             trapno == 0xe ? (ERROR_sig(uc) >> 1) & 1 : 0,
+                             trapno == PAGE_FAULT_TRAP ?
+                             (ERROR_sig(uc) >> 1) & 1 : 0,
                              &MASK_sig(uc));
 }
 
@@ -313,11 +318,13 @@ int cpu_signal_handler(int host_signum, void *pinfo,
 #define TRAP_sig(context)     ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
 #define ERROR_sig(context)    ((context)->uc_mcontext.__gregs[_REG_ERR])
 #define MASK_sig(context)     ((context)->uc_sigmask)
+#define PAGE_FAULT_TRAP       T_PAGEFLT
 #elif defined(__OpenBSD__)
 #define PC_sig(context)       ((context)->sc_rip)
 #define TRAP_sig(context)     ((context)->sc_trapno)
 #define ERROR_sig(context)    ((context)->sc_err)
 #define MASK_sig(context)     ((context)->sc_mask)
+#define PAGE_FAULT_TRAP       T_PAGEFLT
 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 #include <ucontext.h>
 
@@ -325,11 +332,13 @@ int cpu_signal_handler(int host_signum, void *pinfo,
 #define TRAP_sig(context)     ((context)->uc_mcontext.mc_trapno)
 #define ERROR_sig(context)    ((context)->uc_mcontext.mc_err)
 #define MASK_sig(context)     ((context)->uc_sigmask)
+#define PAGE_FAULT_TRAP       T_PAGEFLT
 #else
 #define PC_sig(context)       ((context)->uc_mcontext.gregs[REG_RIP])
 #define TRAP_sig(context)     ((context)->uc_mcontext.gregs[REG_TRAPNO])
 #define ERROR_sig(context)    ((context)->uc_mcontext.gregs[REG_ERR])
 #define MASK_sig(context)     ((context)->uc_sigmask)
+#define PAGE_FAULT_TRAP       0xe
 #endif
 
 int cpu_signal_handler(int host_signum, void *pinfo,
@@ -347,7 +356,8 @@ int cpu_signal_handler(int host_signum, void *pinfo,
 
     pc = PC_sig(uc);
     return handle_cpu_signal(pc, info,
-                             TRAP_sig(uc) == 0xe ? (ERROR_sig(uc) >> 1) & 1 : 0,
+                             TRAP_sig(uc) == PAGE_FAULT_TRAP ?
+                             (ERROR_sig(uc) >> 1) & 1 : 0,
                              &MASK_sig(uc));
 }
 
-- 
2.22.1

Re: [PATCH v2] tcg: Use correct trap number for page faults on *BSD systems

[Richard Henderson]

On 5/6/21 10:38 AM, Warner Losh wrote:
> The trap number for a page fault on BSD systems is T_PAGEFLT not 0xe. 0xe is
> used by Linux and represents the intel hardware trap vector. The BSD kernels,
> however, translate this to T_PAGEFLT in their Xpage, Xtrap0e, Xtrap14, etc fault
> handlers. This is true for i386 and x86_64, though the name of the trap hanlder
> can very on the flavor of BSD. As far as I can tell, Linux doesn't provide a
> define for this value. Invent a new one (PAGE_FAULT_TRAP) and use it instead to
> avoid uglier ifdefs.
> 
> Signed-off-by: Mark Johnston<markj@FreeBSD.org>
> Signed-off-by: Juergen Lock<nox@FreeBSD.org>
> [ Rework to avoid ifdefs and expand it to i386 ]
> Signed-off-by: Warner Losh<imp@bsdimp.com>
> ---
>   accel/tcg/user-exec.c | 14 ++++++++++++--
>   1 file changed, 12 insertions(+), 2 deletions(-)

Queued to tcg-next, thanks.

Looks like this area could use a bit of cleanup...


r~

Re: [PATCH v2] tcg: Use correct trap number for page faults on *BSD systems

[Warner Losh]

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On Thu, May 6, 2021 at 11:51 AM Richard Henderson <
richard.henderson@linaro.org> wrote:

> On 5/6/21 10:38 AM, Warner Losh wrote:
> > The trap number for a page fault on BSD systems is T_PAGEFLT not 0xe.
> 0xe is
> > used by Linux and represents the intel hardware trap vector. The BSD
> kernels,
> > however, translate this to T_PAGEFLT in their Xpage, Xtrap0e, Xtrap14,
> etc fault
> > handlers. This is true for i386 and x86_64, though the name of the trap
> hanlder
> > can very on the flavor of BSD. As far as I can tell, Linux doesn't
> provide a
> > define for this value. Invent a new one (PAGE_FAULT_TRAP) and use it
> instead to
> > avoid uglier ifdefs.
> >
> > Signed-off-by: Mark Johnston<markj@FreeBSD.org>
> > Signed-off-by: Juergen Lock<nox@FreeBSD.org>
> > [ Rework to avoid ifdefs and expand it to i386 ]
> > Signed-off-by: Warner Losh<imp@bsdimp.com>
> > ---
> >   accel/tcg/user-exec.c | 14 ++++++++++++--
> >   1 file changed, 12 insertions(+), 2 deletions(-)
>
> Queued to tcg-next, thanks.
>
> Looks like this area could use a bit of cleanup...
>

No arguments from me there... Thanks!

Warner

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Re: [PATCH v2] tcg: Use correct trap number for page faults on *BSD systems

[Richard Henderson]

On 5/6/21 12:53 PM, Warner Losh wrote:
> 
> 
> On Thu, May 6, 2021 at 11:51 AM Richard Henderson <richard.henderson@linaro.org 
> <mailto:richard.henderson@linaro.org>> wrote:
> 
>     On 5/6/21 10:38 AM, Warner Losh wrote:
>      > The trap number for a page fault on BSD systems is T_PAGEFLT not 0xe. 0xe is
>      > used by Linux and represents the intel hardware trap vector. The BSD
>     kernels,
>      > however, translate this to T_PAGEFLT in their Xpage, Xtrap0e, Xtrap14,
>     etc fault
>      > handlers. This is true for i386 and x86_64, though the name of the trap
>     hanlder
>      > can very on the flavor of BSD. As far as I can tell, Linux doesn't provide a
>      > define for this value. Invent a new one (PAGE_FAULT_TRAP) and use it
>     instead to
>      > avoid uglier ifdefs.
>      >
>      > Signed-off-by: Mark Johnston<markj@FreeBSD.org>
>      > Signed-off-by: Juergen Lock<nox@FreeBSD.org>
>      > [ Rework to avoid ifdefs and expand it to i386 ]
>      > Signed-off-by: Warner Losh<imp@bsdimp.com <mailto:imp@bsdimp.com>>
>      > ---
>      >   accel/tcg/user-exec.c | 14 ++++++++++++--
>      >   1 file changed, 12 insertions(+), 2 deletions(-)
> 
>     Queued to tcg-next, thanks.
> 
>     Looks like this area could use a bit of cleanup...
> 
> 
> No arguments from me there... Thanks!

Dequeueing.

This doesn't work on our "make vm-build-{freebsd,openbsd} images, as Peter 
helpfully pointed out after I sent the pull request.  I don't know enough about 
any of the BSDs to know what's expected.


r~

Re: [PATCH v2] tcg: Use correct trap number for page faults on *BSD systems

[Warner Losh]

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On Fri, May 14, 2021 at 6:23 AM Richard Henderson <
richard.henderson@linaro.org> wrote:

> On 5/6/21 12:53 PM, Warner Losh wrote:
> >
> >
> > On Thu, May 6, 2021 at 11:51 AM Richard Henderson <
> richard.henderson@linaro.org
> > <mailto:richard.henderson@linaro.org>> wrote:
> >
> >     On 5/6/21 10:38 AM, Warner Losh wrote:
> >      > The trap number for a page fault on BSD systems is T_PAGEFLT not
> 0xe. 0xe is
> >      > used by Linux and represents the intel hardware trap vector. The
> BSD
> >     kernels,
> >      > however, translate this to T_PAGEFLT in their Xpage, Xtrap0e,
> Xtrap14,
> >     etc fault
> >      > handlers. This is true for i386 and x86_64, though the name of
> the trap
> >     hanlder
> >      > can very on the flavor of BSD. As far as I can tell, Linux
> doesn't provide a
> >      > define for this value. Invent a new one (PAGE_FAULT_TRAP) and use
> it
> >     instead to
> >      > avoid uglier ifdefs.
> >      >
> >      > Signed-off-by: Mark Johnston<markj@FreeBSD.org>
> >      > Signed-off-by: Juergen Lock<nox@FreeBSD.org>
> >      > [ Rework to avoid ifdefs and expand it to i386 ]
> >      > Signed-off-by: Warner Losh<imp@bsdimp.com <mailto:imp@bsdimp.com
> >>
> >      > ---
> >      >   accel/tcg/user-exec.c | 14 ++++++++++++--
> >      >   1 file changed, 12 insertions(+), 2 deletions(-)
> >
> >     Queued to tcg-next, thanks.
> >
> >     Looks like this area could use a bit of cleanup...
> >
> >
> > No arguments from me there... Thanks!
>
> Dequeueing.
>
> This doesn't work on our "make vm-build-{freebsd,openbsd} images, as Peter
> helpfully pointed out after I sent the pull request.  I don't know enough
> about
> any of the BSDs to know what's expected.
>

OK. I'll take a closer look. It's survived the make vm-build-freebsd in the
past, so
I'm a little surprised at this...

Warner

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