x32: Handle process creation

Allow an x32 process to be started.

Originally-by: H. J. Lu <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>

3 files changed, 34 insertions, 8 deletions

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 5adce1040b1..63c0e058a40 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -28,7 +28,6 @@
 #include <asm/apic.h>
 #include <asm/stacktrace.h>
 #include <asm/nmi.h>
-#include <asm/compat.h>
 #include <asm/smp.h>
 #include <asm/alternative.h>
 
@@ -1595,6 +1594,9 @@ perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
 }
 
 #ifdef CONFIG_COMPAT
+
+#include <asm/compat.h>
+
 static inline int
 perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
 {
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 53dc821f0a6..9e036f0ce5e 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -763,6 +763,21 @@ ENTRY(stub_x32_rt_sigreturn)
         CFI_ENDPROC
 END(stub_x32_rt_sigreturn)
 
+ENTRY(stub_x32_execve)
+        CFI_STARTPROC
+        addq $8, %rsp
+        PARTIAL_FRAME 0
+        SAVE_REST
+        FIXUP_TOP_OF_STACK %r11
+        movq %rsp, %rcx
+        call sys32_execve
+        RESTORE_TOP_OF_STACK %r11
+        movq %rax,RAX(%rsp)
+        RESTORE_REST
+        jmp int_ret_from_sys_call
+        CFI_ENDPROC
+END(stub_x32_execve)
+
 #endif
 
 /*
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 5fe2fbaa56b..a0701da2bd1 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -364,7 +364,9 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp)
 {
         start_thread_common(regs, new_ip, new_sp,
-                            __USER32_CS, __USER32_DS, __USER32_DS);
+                            test_thread_flag(TIF_X32)
+                            ? __USER_CS : __USER32_CS,
+                            __USER_DS, __USER_DS);
 }
 #endif
 
@@ -508,6 +510,7 @@ void set_personality_64bit(void)
 
         /* Make sure to be in 64bit mode */
         clear_thread_flag(TIF_IA32);
+        clear_thread_flag(TIF_X32);
         clear_thread_flag(TIF_ADDR32);
         clear_thread_flag(TIF_X32);
 
@@ -522,22 +525,28 @@ void set_personality_64bit(void)
         current->personality &= ~READ_IMPLIES_EXEC;
 }
 
-void set_personality_ia32(void)
+void set_personality_ia32(bool x32)
 {
         /* inherit personality from parent */
 
         /* Make sure to be in 32bit mode */
-        set_thread_flag(TIF_IA32);
         set_thread_flag(TIF_ADDR32);
-        clear_thread_flag(TIF_X32);
-        current->personality |= force_personality32;
 
         /* Mark the associated mm as containing 32-bit tasks. */
         if (current->mm)
                 current->mm->context.ia32_compat = 1;
 
-        /* Prepare the first "return" to user space */
-        current_thread_info()->status |= TS_COMPAT;
+        if (x32) {
+                clear_thread_flag(TIF_IA32);
+                set_thread_flag(TIF_X32);
+                current->personality &= ~READ_IMPLIES_EXEC;
+        } else {
+                set_thread_flag(TIF_IA32);
+                clear_thread_flag(TIF_X32);
+                current->personality |= force_personality32;
+                /* Prepare the first "return" to user space */
+                current_thread_info()->status |= TS_COMPAT;
+        }
 }
 
 unsigned long get_wchan(struct task_struct *p)