Merge tag 'for-linux-5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

Pull UML updates from Richard Weinberger:

 - Many cleanups and fixes for our virtio code

 - Add support for a pseudo RTC

 - Fix for a possible jailbreak

 - Minor fixes (spelling, header files)

* tag 'for-linux-5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: irq.h: include <asm-generic/irq.h>
  um: io.h: include <linux/types.h>
  um: add a pseudo RTC
  um: remove process stub VMA
  um: rework userspace stubs to not hard-code stub location
  um: separate child and parent errors in clone stub
  um: defer killing userspace on page table update failures
  um: mm: check more comprehensively for stub changes
  um: print register names in wait_for_stub
  um: hostfs: use a kmem cache for inodes
  mm: Remove arch_remap() and mm-arch-hooks.h
  um: fix spelling mistake in Kconfig "privleges" -> "privileges"
  um: virtio: allow devices to be configured for wakeup
  um: time-travel: rework interrupt handling in ext mode
  um: virtio: disable VQs during suspend
  um: virtio: fix handling of messages without payload
  um: virtio: clean up a comment

6 files changed, 63 insertions, 35 deletions

diff --git a/arch/x86/um/os-Linux/task_size.c b/arch/x86/um/os-Linux/task_size.c
index e62174638f00..1dc9adc20b1c 100644
--- a/arch/x86/um/os-Linux/task_size.c
+++ b/arch/x86/um/os-Linux/task_size.c
@@ -145,7 +145,7 @@ out:
 unsigned long os_get_top_address(void)
 {
 	/* The old value of CONFIG_TOP_ADDR */
-	return 0x7fc0000000;
+	return 0x7fc0002000;
 }
 
 #endif
diff --git a/arch/x86/um/shared/sysdep/stub_32.h b/arch/x86/um/shared/sysdep/stub_32.h
index 51fd256c75f0..c3891c1ada26 100644
--- a/arch/x86/um/shared/sysdep/stub_32.h
+++ b/arch/x86/um/shared/sysdep/stub_32.h
@@ -7,8 +7,8 @@
 #define __SYSDEP_STUB_H
 
 #include <asm/ptrace.h>
+#include <generated/asm-offsets.h>
 
-#define STUB_SYSCALL_RET EAX
 #define STUB_MMAP_NR __NR_mmap2
 #define MMAP_OFFSET(o) ((o) >> UM_KERN_PAGE_SHIFT)
 
@@ -77,17 +77,28 @@ static inline void trap_myself(void)
 	__asm("int3");
 }
 
-static inline void remap_stack(int fd, unsigned long offset)
+static void inline remap_stack_and_trap(void)
 {
-	__asm__ volatile ("movl %%eax,%%ebp ; movl %0,%%eax ; int $0x80 ;"
-			  "movl %7, %%ebx ; movl %%eax, (%%ebx)"
-			  : : "g" (STUB_MMAP_NR), "b" (STUB_DATA),
-			    "c" (UM_KERN_PAGE_SIZE),
-			    "d" (PROT_READ | PROT_WRITE),
-			    "S" (MAP_FIXED | MAP_SHARED), "D" (fd),
-			    "a" (offset),
-			    "i" (&((struct stub_data *) STUB_DATA)->err)
-			  : "memory");
+	__asm__ volatile (
+		"movl %%esp,%%ebx ;"
+		"andl %0,%%ebx ;"
+		"movl %1,%%eax ;"
+		"movl %%ebx,%%edi ; addl %2,%%edi ; movl (%%edi),%%edi ;"
+		"movl %%ebx,%%ebp ; addl %3,%%ebp ; movl (%%ebp),%%ebp ;"
+		"int $0x80 ;"
+		"addl %4,%%ebx ; movl %%eax, (%%ebx) ;"
+		"int $3"
+		: :
+		"g" (~(UM_KERN_PAGE_SIZE - 1)),
+		"g" (STUB_MMAP_NR),
+		"g" (UML_STUB_FIELD_FD),
+		"g" (UML_STUB_FIELD_OFFSET),
+		"g" (UML_STUB_FIELD_CHILD_ERR),
+		"c" (UM_KERN_PAGE_SIZE),
+		"d" (PROT_READ | PROT_WRITE),
+		"S" (MAP_FIXED | MAP_SHARED)
+		:
+		"memory");
 }
 
 #endif
diff --git a/arch/x86/um/shared/sysdep/stub_64.h b/arch/x86/um/shared/sysdep/stub_64.h
index 994df93c5ed3..6e2626b77a2e 100644
--- a/arch/x86/um/shared/sysdep/stub_64.h
+++ b/arch/x86/um/shared/sysdep/stub_64.h
@@ -7,8 +7,8 @@
 #define __SYSDEP_STUB_H
 
 #include <sysdep/ptrace_user.h>
+#include <generated/asm-offsets.h>
 
-#define STUB_SYSCALL_RET PT_INDEX(RAX)
 #define STUB_MMAP_NR __NR_mmap
 #define MMAP_OFFSET(o) (o)
 
@@ -82,18 +82,30 @@ static inline void trap_myself(void)
 	__asm("int3");
 }
 
-static inline void remap_stack(long fd, unsigned long offset)
+static inline void remap_stack_and_trap(void)
 {
-	__asm__ volatile ("movq %4,%%r10 ; movq %5,%%r8 ; "
-			  "movq %6, %%r9; " __syscall "; movq %7, %%rbx ; "
-			  "movq %%rax, (%%rbx)":
-			  : "a" (STUB_MMAP_NR), "D" (STUB_DATA),
-			    "S" (UM_KERN_PAGE_SIZE),
-			    "d" (PROT_READ | PROT_WRITE),
-                            "g" (MAP_FIXED | MAP_SHARED), "g" (fd),
-			    "g" (offset),
-			    "i" (&((struct stub_data *) STUB_DATA)->err)
-			  : __syscall_clobber, "r10", "r8", "r9" );
+	__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" (~(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" (UM_KERN_PAGE_SIZE),
+		"d" (PROT_READ | PROT_WRITE)
+		:
+		__syscall_clobber, "r10", "r8", "r9");
 }
 
 #endif
diff --git a/arch/x86/um/stub_32.S b/arch/x86/um/stub_32.S
index a193e88536a9..8291899e6aaf 100644
--- a/arch/x86/um/stub_32.S
+++ b/arch/x86/um/stub_32.S
@@ -5,21 +5,22 @@
 
 	.globl batch_syscall_stub
 batch_syscall_stub:
-	/* load pointer to first operation */
-	mov	$(STUB_DATA+8), %esp
-
+	/* %esp comes in as "top of page" */
+	mov %esp, %ecx
+	/* %esp has pointer to first operation */
+	add $8, %esp
 again:
 	/* load length of additional data */
 	mov	0x0(%esp), %eax
 
 	/* if(length == 0) : end of list */
 	/* write possible 0 to header */
-	mov	%eax, STUB_DATA+4
+	mov	%eax, 0x4(%ecx)
 	cmpl	$0, %eax
 	jz	done
 
 	/* save current pointer */
-	mov	%esp, STUB_DATA+4
+	mov	%esp, 0x4(%ecx)
 
 	/* skip additional data */
 	add	%eax, %esp
@@ -38,6 +39,10 @@ again:
 	/* execute syscall */
 	int	$0x80
 
+	/* restore top of page pointer in %ecx */
+	mov	%esp, %ecx
+	andl	$(~UM_KERN_PAGE_SIZE) + 1, %ecx
+
 	/* check return value */
 	pop	%ebx
 	cmp	%ebx, %eax
@@ -45,7 +50,7 @@ again:
 
 done:
 	/* save return value */
-	mov	%eax, STUB_DATA
+	mov	%eax, (%ecx)
 
 	/* stop */
 	int3
diff --git a/arch/x86/um/stub_64.S b/arch/x86/um/stub_64.S
index 8a95c5b2eaf9..f3404640197a 100644
--- a/arch/x86/um/stub_64.S
+++ b/arch/x86/um/stub_64.S
@@ -4,9 +4,8 @@
 .section .__syscall_stub, "ax"
 	.globl batch_syscall_stub
 batch_syscall_stub:
-	mov	$(STUB_DATA), %rbx
-	/* load pointer to first operation */
-	mov	%rbx, %rsp
+	/* %rsp has the pointer to first operation */
+	mov	%rsp, %rbx
 	add	$0x10, %rsp
 again:
 	/* load length of additional data */
diff --git a/arch/x86/um/stub_segv.c b/arch/x86/um/stub_segv.c
index 27361cbb7ca9..21836eaf1725 100644
--- a/arch/x86/um/stub_segv.c
+++ b/arch/x86/um/stub_segv.c
@@ -11,10 +11,11 @@
 void __attribute__ ((__section__ (".__syscall_stub")))
 stub_segv_handler(int sig, siginfo_t *info, void *p)
 {
+	int stack;
 	ucontext_t *uc = p;
+	struct faultinfo *f = (void *)(((unsigned long)&stack) & ~(UM_KERN_PAGE_SIZE - 1));
 
-	GET_FAULTINFO_FROM_MC(*((struct faultinfo *) STUB_DATA),
-			      &uc->uc_mcontext);
+	GET_FAULTINFO_FROM_MC(*f, &uc->uc_mcontext);
 	trap_myself();
 }