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>

1 files changed, 24 insertions, 2 deletions

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 7938b84e4506..e7f68b49c01a 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -6,6 +6,7 @@
  */
 #include <linux/types.h>
 #include <linux/sched.h>
+#include <asm/processor.h>
 #include <asm/user32.h>
 #include <asm/unistd.h>
 
@@ -187,7 +188,20 @@ struct compat_shmid64_ds {
 /*
  * The type of struct elf_prstatus.pr_reg in compatible core dumps.
  */
+#ifdef CONFIG_X86_X32_ABI
+typedef struct user_regs_struct compat_elf_gregset_t;
+
+#define PR_REG_SIZE(S) (test_thread_flag(TIF_IA32) ? 68 : 216)
+#define PRSTATUS_SIZE(S) (test_thread_flag(TIF_IA32) ? 144 : 296)
+#define SET_PR_FPVALID(S,V) \
+  do { *(int *) (((void *) &((S)->pr_reg)) + PR_REG_SIZE(0)) = (V); } \
+  while (0)
+
+#define COMPAT_USE_64BIT_TIME \
+        (!!(task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT))
+#else
 typedef struct user_regs_struct32 compat_elf_gregset_t;
+#endif
 
 /*
  * A pointer passed in from user mode. This should not
@@ -209,8 +223,16 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
 
 static inline void __user *arch_compat_alloc_user_space(long len)
 {
-        struct pt_regs *regs = task_pt_regs(current);
-        return (void __user *)regs->sp - len;
+        compat_uptr_t sp;
+
+        if (test_thread_flag(TIF_IA32)) {
+                sp = task_pt_regs(current)->sp;
+        } else {
+                /* -128 for the x32 ABI redzone */
+                sp = percpu_read(old_rsp) - 128;
+        }
+
+        return (void __user *)round_down(sp - len, 16);
 }
 
 static inline bool is_compat_task(void)