[PATCH 2/3] x86/entry: Make #PF/NMI/INT0x82 more amenable to livepatching

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

It is bad form to have inter-function fallthrough.  It only functions right
now because alignment padding bytes are NOPs.

However, it also interferes with livepatching binary diffs, because the
implicit grouping of the two functions isn't expressed in the ELF metadata.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
CC: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
 xen/arch/x86/x86_64/compat/entry.S | 1 +
 xen/arch/x86/x86_64/entry.S        | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/xen/arch/x86/x86_64/compat/entry.S 
b/xen/arch/x86/x86_64/compat/entry.S
index 49811a56e965..4fbd89cea1a9 100644
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -29,6 +29,7 @@ FUNC(entry_int82)
 
         mov   %rsp, %rdi
         call  do_entry_int82
+        jmp   compat_test_all_events
 END(entry_int82)
 
 /* %rbx: struct vcpu */
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index c3f6b667a72a..fc64ef1fd460 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -723,7 +723,9 @@ END(common_interrupt)
 FUNC(entry_PF)
         ENDBR64
         movl  $X86_EXC_PF, 4(%rsp)
+        jmp   handle_exception
 END(entry_PF)
+
 /* No special register assumptions. */
 FUNC(handle_exception, 0)
         ALTERNATIVE "", clac, X86_FEATURE_XEN_SMAP
@@ -1023,6 +1025,7 @@ FUNC(entry_NMI)
         ENDBR64
         pushq $0
         movl  $X86_EXC_NMI, 4(%rsp)
+        jmp   handle_ist_exception
 END(entry_NMI)
 
 FUNC(handle_ist_exception)
-- 
2.30.2