[xen staging] x86: mark hypercall argument regs clobbering for intended fall-through

[patchbot@xxxxxxx]

commit 140931aa2894991d9d6f1b2ba6ca275e1bc56259
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Jul 9 08:32:07 2021 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jul 9 08:32:07 2021 +0200

    x86: mark hypercall argument regs clobbering for intended fall-through
    
    The CIDs below are all for the PV side of things, yet while at it take
    care of the HVM side as well.
    
    Coverity-ID: 1485896, 1485901, 1485906, 1485910, 1485911,
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hypercall.c | 20 ++++++++++----------
 xen/arch/x86/pv/hypercall.c  | 20 ++++++++++----------
 2 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c
index 9e1f7249f3..263d5407ea 100644
--- a/xen/arch/x86/hvm/hypercall.c
+++ b/xen/arch/x86/hvm/hypercall.c
@@ -248,11 +248,11 @@ int hvm_hypercall(struct cpu_user_regs *regs)
         /* Deliberately corrupt parameter regs not used by this hypercall. */
         switch ( hypercall_args_table[eax].native )
         {
-        case 0: rdi = 0xdeadbeefdeadf00dUL;
-        case 1: rsi = 0xdeadbeefdeadf00dUL;
-        case 2: rdx = 0xdeadbeefdeadf00dUL;
-        case 3: r10 = 0xdeadbeefdeadf00dUL;
-        case 4: r8 = 0xdeadbeefdeadf00dUL;
+        case 0: rdi = 0xdeadbeefdeadf00dUL; fallthrough;
+        case 1: rsi = 0xdeadbeefdeadf00dUL; fallthrough;
+        case 2: rdx = 0xdeadbeefdeadf00dUL; fallthrough;
+        case 3: r10 = 0xdeadbeefdeadf00dUL; fallthrough;
+        case 4: r8 = 0xdeadbeefdeadf00dUL; fallthrough;
         case 5: r9 = 0xdeadbeefdeadf00dUL;
         }
 #endif
@@ -266,11 +266,11 @@ int hvm_hypercall(struct cpu_user_regs *regs)
             /* Deliberately corrupt parameter regs used by this hypercall. */
             switch ( hypercall_args_table[eax].native )
             {
-            case 6: regs->r9  = 0xdeadbeefdeadf00dUL;
-            case 5: regs->r8  = 0xdeadbeefdeadf00dUL;
-            case 4: regs->r10 = 0xdeadbeefdeadf00dUL;
-            case 3: regs->rdx = 0xdeadbeefdeadf00dUL;
-            case 2: regs->rsi = 0xdeadbeefdeadf00dUL;
+            case 6: regs->r9  = 0xdeadbeefdeadf00dUL; fallthrough;
+            case 5: regs->r8  = 0xdeadbeefdeadf00dUL; fallthrough;
+            case 4: regs->r10 = 0xdeadbeefdeadf00dUL; fallthrough;
+            case 3: regs->rdx = 0xdeadbeefdeadf00dUL; fallthrough;
+            case 2: regs->rsi = 0xdeadbeefdeadf00dUL; fallthrough;
             case 1: regs->rdi = 0xdeadbeefdeadf00dUL;
             }
         }
diff --git a/xen/arch/x86/pv/hypercall.c b/xen/arch/x86/pv/hypercall.c
index 200b8a05b0..03939bdfcf 100644
--- a/xen/arch/x86/pv/hypercall.c
+++ b/xen/arch/x86/pv/hypercall.c
@@ -150,11 +150,11 @@ void pv_hypercall(struct cpu_user_regs *regs)
         /* Deliberately corrupt parameter regs not used by this hypercall. */
         switch ( hypercall_args_table[eax].native )
         {
-        case 0: rdi = 0xdeadbeefdeadf00dUL;
-        case 1: rsi = 0xdeadbeefdeadf00dUL;
-        case 2: rdx = 0xdeadbeefdeadf00dUL;
-        case 3: r10 = 0xdeadbeefdeadf00dUL;
-        case 4: r8 = 0xdeadbeefdeadf00dUL;
+        case 0: rdi = 0xdeadbeefdeadf00dUL; fallthrough;
+        case 1: rsi = 0xdeadbeefdeadf00dUL; fallthrough;
+        case 2: rdx = 0xdeadbeefdeadf00dUL; fallthrough;
+        case 3: r10 = 0xdeadbeefdeadf00dUL; fallthrough;
+        case 4: r8 = 0xdeadbeefdeadf00dUL; fallthrough;
         case 5: r9 = 0xdeadbeefdeadf00dUL;
         }
 #endif
@@ -173,11 +173,11 @@ void pv_hypercall(struct cpu_user_regs *regs)
             /* Deliberately corrupt parameter regs used by this hypercall. */
             switch ( hypercall_args_table[eax].native )
             {
-            case 6: regs->r9  = 0xdeadbeefdeadf00dUL;
-            case 5: regs->r8  = 0xdeadbeefdeadf00dUL;
-            case 4: regs->r10 = 0xdeadbeefdeadf00dUL;
-            case 3: regs->rdx = 0xdeadbeefdeadf00dUL;
-            case 2: regs->rsi = 0xdeadbeefdeadf00dUL;
+            case 6: regs->r9  = 0xdeadbeefdeadf00dUL; fallthrough;
+            case 5: regs->r8  = 0xdeadbeefdeadf00dUL; fallthrough;
+            case 4: regs->r10 = 0xdeadbeefdeadf00dUL; fallthrough;
+            case 3: regs->rdx = 0xdeadbeefdeadf00dUL; fallthrough;
+            case 2: regs->rsi = 0xdeadbeefdeadf00dUL; fallthrough;
             case 1: regs->rdi = 0xdeadbeefdeadf00dUL;
             }
         }
--
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