[PATCH 01/16] x86/traps: Drop last_extable_addr

From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Wei Liu" <wl@xen.org>, "Jan Beulich" <JBeulich@suse.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [PATCH 01/16] x86/traps: Drop last_extable_addr
Date: Fri, 1 May 2020 23:58:23 +0100	[thread overview]
Message-ID: <20200501225838.9866-2-andrew.cooper3@citrix.com> (raw)
In-Reply-To: <20200501225838.9866-1-andrew.cooper3@citrix.com>

The only user of this facility is dom_crash_sync_extable() by passing 0 into
asm_domain_crash_synchronous().  The common error cases are already covered
with show_page_walk(), leaving only %ss/%fs selector/segment errors in the
compat case.

Point at dom_crash_sync_extable in the error message, which is about as good
as the error hints from other users of asm_domain_crash_synchronous(), and
drop last_extable_addr.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wl@xen.org>
CC: Roger Pau Monné <roger.pau@citrix.com>
---
 xen/arch/x86/traps.c        | 11 +----------
 xen/arch/x86/x86_64/entry.S |  2 +-
 2 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 33e5d21ece..fe9457cdb6 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -96,7 +96,6 @@ static char __read_mostly opt_nmi[10] = "fatal";
 string_param("nmi", opt_nmi);
 
 DEFINE_PER_CPU(uint64_t, efer);
-static DEFINE_PER_CPU(unsigned long, last_extable_addr);
 
 DEFINE_PER_CPU_READ_MOSTLY(seg_desc_t *, gdt);
 DEFINE_PER_CPU_READ_MOSTLY(l1_pgentry_t, gdt_l1e);
@@ -786,7 +785,6 @@ static void do_trap(struct cpu_user_regs *regs)
     {
         dprintk(XENLOG_ERR, "Trap %u: %p [%ps] -> %p\n",
                 trapnr, _p(regs->rip), _p(regs->rip), _p(fixup));
-        this_cpu(last_extable_addr) = regs->rip;
         regs->rip = fixup;
         return;
     }
@@ -1099,7 +1097,6 @@ void do_invalid_op(struct cpu_user_regs *regs)
  die:
     if ( (fixup = search_exception_table(regs)) != 0 )
     {
-        this_cpu(last_extable_addr) = regs->rip;
         regs->rip = fixup;
         return;
     }
@@ -1122,7 +1119,6 @@ void do_int3(struct cpu_user_regs *regs)
 
         if ( (fixup = search_exception_table(regs)) != 0 )
         {
-            this_cpu(last_extable_addr) = regs->rip;
             dprintk(XENLOG_DEBUG, "Trap %u: %p [%ps] -> %p\n",
                     TRAP_int3, _p(regs->rip), _p(regs->rip), _p(fixup));
             regs->rip = fixup;
@@ -1461,7 +1457,6 @@ void do_page_fault(struct cpu_user_regs *regs)
             perfc_incr(copy_user_faults);
             if ( unlikely(regs->error_code & PFEC_reserved_bit) )
                 reserved_bit_page_fault(addr, regs);
-            this_cpu(last_extable_addr) = regs->rip;
             regs->rip = fixup;
             return;
         }
@@ -1591,7 +1586,6 @@ void do_general_protection(struct cpu_user_regs *regs)
     {
         dprintk(XENLOG_INFO, "GPF (%04x): %p [%ps] -> %p\n",
                 regs->error_code, _p(regs->rip), _p(regs->rip), _p(fixup));
-        this_cpu(last_extable_addr) = regs->rip;
         regs->rip = fixup;
         return;
     }
@@ -2085,10 +2079,7 @@ void asm_domain_crash_synchronous(unsigned long addr)
      */
     clac();
 
-    if ( addr == 0 )
-        addr = this_cpu(last_extable_addr);
-
-    printk("domain_crash_sync called from entry.S: fault at %p %pS\n",
+    printk("domain_crash_sync called from entry.S: issue around %p %pS\n",
            _p(addr), _p(addr));
 
     __domain_crash(current->domain);
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index d55453f3f3..a3ce298529 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -527,7 +527,7 @@ ENTRY(dom_crash_sync_extable)
         sete  %al
         leal  (%rax,%rax,2),%eax
         orb   %al,UREGS_cs(%rsp)
-        xorl  %edi,%edi
+        lea   dom_crash_sync_extable(%rip), %rdi
         jmp   asm_domain_crash_synchronous /* Does not return */
         .popsection
 #endif /* CONFIG_PV */
-- 
2.11.0


