1 files changed, 14 insertions, 8 deletions

diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index b86feabed69b..518bb99c3394 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -50,7 +50,12 @@
         /*
          * Reload arg registers from stack in case ptrace changed them.
          * We don't reload %eax because syscall_trace_enter() returned
-         * the value it wants us to use in the table lookup.
+         * the %rax value we should see.  Instead, we just truncate that
+         * value to 32 bits again as we did on entry from user mode.
+         * If it's a new value set by user_regset during entry tracing,
+         * this matches the normal truncation of the user-mode value.
+         * If it's -1 to make us punt the syscall, then (u32)-1 is still
+         * an appropriately invalid value.
          */
         .macro LOAD_ARGS32 offset, _r9=0
         .if \_r9
@@ -60,6 +65,7 @@
         movl \offset+48(%rsp),%edx
         movl \offset+56(%rsp),%esi
         movl \offset+64(%rsp),%edi
+        movl %eax,%eax                  /* zero extension */
         .endm
         
         .macro CFI_STARTPROC32 simple
@@ -153,7 +159,7 @@ ENTRY(ia32_sysenter_target)
         testl  $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
         CFI_REMEMBER_STATE
         jnz  sysenter_tracesys
-        cmpl    $(IA32_NR_syscalls-1),%eax
+        cmpq    $(IA32_NR_syscalls-1),%rax
         ja      ia32_badsys
 sysenter_do_call:
         IA32_ARG_FIXUP
@@ -195,7 +201,7 @@ sysexit_from_sys_call:
         movl $AUDIT_ARCH_I386,%edi      /* 1st arg: audit arch */
         call audit_syscall_entry
         movl RAX-ARGOFFSET(%rsp),%eax   /* reload syscall number */
-        cmpl $(IA32_NR_syscalls-1),%eax
+        cmpq $(IA32_NR_syscalls-1),%rax
         ja ia32_badsys
         movl %ebx,%edi                  /* reload 1st syscall arg */
         movl RCX-ARGOFFSET(%rsp),%esi   /* reload 2nd syscall arg */
@@ -248,7 +254,7 @@ sysenter_tracesys:
         call    syscall_trace_enter
         LOAD_ARGS32 ARGOFFSET  /* reload args from stack in case ptrace changed it */
         RESTORE_REST
-        cmpl    $(IA32_NR_syscalls-1),%eax
+        cmpq    $(IA32_NR_syscalls-1),%rax
         ja      int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */
         jmp     sysenter_do_call
         CFI_ENDPROC
@@ -314,7 +320,7 @@ ENTRY(ia32_cstar_target)
         testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
         CFI_REMEMBER_STATE
         jnz   cstar_tracesys
-        cmpl $IA32_NR_syscalls-1,%eax
+        cmpq $IA32_NR_syscalls-1,%rax
         ja  ia32_badsys
 cstar_do_call:
         IA32_ARG_FIXUP 1
@@ -367,7 +373,7 @@ cstar_tracesys:
         LOAD_ARGS32 ARGOFFSET, 1  /* reload args from stack in case ptrace changed it */
         RESTORE_REST
         xchgl %ebp,%r9d
-        cmpl $(IA32_NR_syscalls-1),%eax
+        cmpq $(IA32_NR_syscalls-1),%rax
         ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */
         jmp cstar_do_call
 END(ia32_cstar_target)
@@ -425,7 +431,7 @@ ENTRY(ia32_syscall)
         orl   $TS_COMPAT,TI_status(%r10)
         testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
         jnz ia32_tracesys
-        cmpl $(IA32_NR_syscalls-1),%eax
+        cmpq $(IA32_NR_syscalls-1),%rax
         ja ia32_badsys
 ia32_do_call:
         IA32_ARG_FIXUP
@@ -444,7 +450,7 @@ ia32_tracesys:
         call syscall_trace_enter
         LOAD_ARGS32 ARGOFFSET  /* reload args from stack in case ptrace changed it */
         RESTORE_REST
-        cmpl $(IA32_NR_syscalls-1),%eax
+        cmpq $(IA32_NR_syscalls-1),%rax
         ja  int_ret_from_sys_call       /* ia32_tracesys has set RAX(%rsp) */
         jmp ia32_do_call
 END(ia32_syscall)