1 files changed, 57 insertions, 28 deletions

diff --git a/arch/x86/um/shared/sysdep/stub_64.h b/arch/x86/um/shared/sysdep/stub_64.h
index b24168ef0ac4..9cfd31afa769 100644
--- a/arch/x86/um/shared/sysdep/stub_64.h
+++ b/arch/x86/um/shared/sysdep/stub_64.h
@@ -6,9 +6,11 @@
 #ifndef __SYSDEP_STUB_H
 #define __SYSDEP_STUB_H
 
+#include <stddef.h>
 #include <sysdep/ptrace_user.h>
 #include <generated/asm-offsets.h>
 #include <linux/stddef.h>
+#include <asm/prctl.h>
 
 #define STUB_MMAP_NR __NR_mmap
 #define MMAP_OFFSET(o) (o)
@@ -27,6 +29,17 @@ static __always_inline long stub_syscall0(long syscall)
 	return ret;
 }
 
+static __always_inline long stub_syscall1(long syscall, long arg1)
+{
+	long ret;
+
+	__asm__ volatile (__syscall
+		: "=a" (ret)
+		: "0" (syscall), "D" (arg1) : __syscall_clobber );
+
+	return ret;
+}
+
 static __always_inline long stub_syscall2(long syscall, long arg1, long arg2)
 {
 	long ret;
@@ -79,35 +92,25 @@ static __always_inline long stub_syscall5(long syscall, long arg1, long arg2,
 	return ret;
 }
 
-static __always_inline void trap_myself(void)
+static __always_inline long stub_syscall6(long syscall, long arg1, long arg2,
+					  long arg3, long arg4, long arg5,
+					  long arg6)
 {
-	__asm("int3");
+	long ret;
+
+	__asm__ volatile ("movq %5,%%r10 ; movq %6,%%r8 ; movq %7,%%r9 ; "
+		__syscall
+		: "=a" (ret)
+		: "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3),
+		  "g" (arg4), "g" (arg5), "g" (arg6)
+		: __syscall_clobber, "r10", "r8", "r9");
+
+	return ret;
 }
 
-static __always_inline void remap_stack_and_trap(void)
+static __always_inline void trap_myself(void)
 {
-	__asm__ volatile (
-		"movq %0,%%rax ;"
-		"movq %%rsp,%%rdi ;"
-		"andq %1,%%rdi ;"
-		"movq %2,%%r10 ;"
-		"movq %%rdi,%%r8 ; addq %3,%%r8 ; movq (%%r8),%%r8 ;"
-		"movq %%rdi,%%r9 ; addq %4,%%r9 ; movq (%%r9),%%r9 ;"
-		__syscall ";"
-		"movq %%rsp,%%rdi ; andq %1,%%rdi ;"
-		"addq %5,%%rdi ; movq %%rax, (%%rdi) ;"
-		"int3"
-		: :
-		"g" (STUB_MMAP_NR),
-		"g" (~(STUB_DATA_PAGES * UM_KERN_PAGE_SIZE - 1)),
-		"g" (MAP_FIXED | MAP_SHARED),
-		"g" (UML_STUB_FIELD_FD),
-		"g" (UML_STUB_FIELD_OFFSET),
-		"g" (UML_STUB_FIELD_CHILD_ERR),
-		"S" (STUB_DATA_PAGES * UM_KERN_PAGE_SIZE),
-		"d" (PROT_READ | PROT_WRITE)
-		:
-		__syscall_clobber, "r10", "r8", "r9");
+	__asm("int3");
 }
 
 static __always_inline void *get_stub_data(void)
@@ -115,11 +118,37 @@ static __always_inline void *get_stub_data(void)
 	unsigned long ret;
 
 	asm volatile (
-		"movq %%rsp,%0 ;"
-		"andq %1,%0"
+		"lea 0(%%rip), %0;"
+		"andq %1, %0 ;"
+		"addq %2, %0 ;"
 		: "=a" (ret)
-		: "g" (~(STUB_DATA_PAGES * UM_KERN_PAGE_SIZE - 1)));
+		: "g" (~(UM_KERN_PAGE_SIZE - 1)),
+		  "g" (UM_KERN_PAGE_SIZE));
 
 	return (void *)ret;
 }
+
+#define stub_start(fn)							\
+	asm volatile (							\
+		"subq %0,%%rsp ;"					\
+		"movq %1,%%rax ;"					\
+		"call *%%rax ;"						\
+		:: "i" ((1 + STUB_DATA_PAGES) * UM_KERN_PAGE_SIZE),	\
+		   "i" (&fn))
+
+static __always_inline void
+stub_seccomp_restore_state(struct stub_data_arch *arch)
+{
+	/*
+	 * We could use _writefsbase_u64/_writegsbase_u64 if the host reports
+	 * support in the hwcaps (HWCAP2_FSGSBASE).
+	 */
+	if (arch->sync & STUB_SYNC_FS_BASE)
+		stub_syscall2(__NR_arch_prctl, ARCH_SET_FS, arch->fs_base);
+	if (arch->sync & STUB_SYNC_GS_BASE)
+		stub_syscall2(__NR_arch_prctl, ARCH_SET_GS, arch->gs_base);
+
+	arch->sync = 0;
+}
+
 #endif