[PATCH v2 0/1] Use correct trap number for *BSD

[PATCH v2 0/1] Use correct trap number for *BSD

[Warner Losh]

This is a resend of a patch I sent back in March that was missing the proper
includes due to a rebasing mistake.

The issue is that all the BSDs use T_PAGEFLT to signal a page fault on x86,
while linux uses 0xe. The patch harmonizes the different ways this can be
spelled, as explained in the patch itself.

Warner Losh (1):
  tcg: Use correct trap number for page faults on *BSD systems

 accel/tcg/user-exec.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

-- 
2.22.1

[PATCH v2 0/1] Use correct trap number for *BSD

[Warner Losh]

This is a resend of a patch I sent back in March that was missing the proper
includes due to a rebasing mistake.

Warner Losh (1):
  tcg: Use correct trap number for page faults on *BSD systems

 accel/tcg/user-exec.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

-- 
2.22.1

[PATCH v2 1/1] 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 | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index fb2d43e6a9..e2d0165670 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -254,28 +254,35 @@ void *probe_access(CPUArchState *env, target_ulong addr, int size,
 
 #if defined(__NetBSD__)
 #include <ucontext.h>
+#include <machine/trap.h>
 
 #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      T_PAGEFLT
 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 #include <ucontext.h>
+#include <machine/trap.h>
 
 #define EIP_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_eip))
 #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__)
+#include <machine/trap.h>
 #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,
@@ -301,34 +308,42 @@ 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));
 }
 
 #elif defined(__x86_64__)
 
 #ifdef __NetBSD__
+#include <machine/trap.h>
 #define PC_sig(context)       _UC_MACHINE_PC(context)
 #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__)
+#include <machine/trap.h>
 #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>
+#include <machine/trap.h>
 
 #define PC_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_rip))
 #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,
@@ -346,7 +361,8 @@ 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 0/1] Use correct trap number for *BSD

[Warner Losh]

[-- Attachment #1: Type: text/plain, Size: 770 bytes --]

On Thu, Jun 24, 2021 at 10:57 PM Warner Losh <imp@bsdimp.com> wrote:

> This is a resend of a patch I sent back in March that was missing the
> proper
> includes due to a rebasing mistake.
>
> The issue is that all the BSDs use T_PAGEFLT to signal a page fault on x86,
> while linux uses 0xe. The patch harmonizes the different ways this can be
> spelled, as explained in the patch itself.
>

I forgot to mention that I've setup NetBSD and OpenBSD bhyve instances
to compile and test these changes to make double sure that they will pass
through the qemu CI.


> Warner Losh (1):
>   tcg: Use correct trap number for page faults on *BSD systems
>
>  accel/tcg/user-exec.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
>
> --
> 2.22.1
>
>

[-- Attachment #2: Type: text/html, Size: 1311 bytes --]

Re: [PATCH v2 1/1] tcg: Use correct trap number for page faults on *BSD systems

[Richard Henderson]

On 6/24/21 9:57 PM, 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 | 20 ++++++++++++++++++--
>   1 file changed, 18 insertions(+), 2 deletions(-)

Thanks, queued to tcg-next.


r~