[CRIU] [PATCH 14/22] restorer: introduced the multiarch support into the restorer.

[Alexander Kartashov]

* Introduced the macro RT_SIGFRAME_UC to access the user context of a sigframe.

* Introduced TLS restoration for ARM.

* Don't touch a VMA that lies outside the virtual address space area 0..TASK_SIZE,
  because VM above TASK_SIZE is read-only but some areas are mapped on ARM
  into the process address space.

* Introduced the macro SIGFRAME_OFFSET to tune the beginning of a sigframe
  on different architectures.

Signed-off-by: Alexander Kartashov <alekskartashov at parallels.com>
---
 arch/x86/include/asm/restorer.h |    4 ++++
 include/restorer.h              |   14 +++++++++-----
 pie/restorer.c                  |   23 +++++++++++++++++++----
 3 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/restorer.h b/arch/x86/include/asm/restorer.h
index 1ccc93c..4518064 100644
--- a/arch/x86/include/asm/restorer.h
+++ b/arch/x86/include/asm/restorer.h
@@ -129,9 +129,13 @@ struct rt_sigframe {
 		     : "r"(ret)					\
 		     : "memory")
 
+#define RT_SIGFRAME_UC(rt_sigframe) rt_sigframe->uc
+
 
 int restore_gpregs(struct rt_sigframe *f, UserX86RegsEntry *r);
 
 int restore_fpu(struct rt_sigframe *sigframe, struct thread_restore_args *args);
 
+static void __attribute__ ((unused)) restore_tls(u32 tls) { }
+
 #endif
diff --git a/include/restorer.h b/include/restorer.h
index 7548ae1..3bb40b9 100644
--- a/include/restorer.h
+++ b/include/restorer.h
@@ -17,10 +17,6 @@
 #include "../protobuf/creds.pb-c.h"
 #include "../protobuf/core.pb-c.h"
 
-#ifndef CONFIG_X86_64
-# error Only x86-64 is supported
-#endif
-
 struct task_restore_core_args;
 struct thread_restore_args;
 
@@ -67,7 +63,10 @@ struct thread_restore_args {
 	struct restore_mem_zone		mem_zone;
 
 	int				pid;
-	UserX86RegsEntry		gpregs;
+	UserRegsEntry		        gpregs;
+
+	u32				tls;
+
 	u64				clear_tid_addr;
 
 	bool				has_futex;
@@ -126,6 +125,7 @@ struct task_restore_core_args {
 	u64				mm_saved_auxv[AT_VECTOR_SIZE];
 	u32				mm_saved_auxv_size;
 	char				comm[TASK_COMM_LEN];
+	uint32_t                        tls;
 
 	int				*rst_tcp_socks;
 	int				rst_tcp_socks_size;
@@ -199,4 +199,8 @@ find_shmem(struct shmems *shmems, unsigned long shmid)
 			(vma_entry_is(vma, VMA_ANON_PRIVATE) || \
 			vma_entry_is(vma, VMA_FILE_PRIVATE)))
 
+#define SIGFRAME_OFFSET 8
+
+#include "asm/memcpy_64.h"
+
 #endif /* __CR_RESTORER_H__ */
diff --git a/pie/restorer.c b/pie/restorer.c
index 04e7ab5..a9b4448 100644
--- a/pie/restorer.c
+++ b/pie/restorer.c
@@ -156,7 +156,7 @@ static int restore_thread_common(struct rt_sigframe *sigframe,
 	}
 
 	if (args->has_blk_sigset)
-		sigframe->uc.uc_sigmask.sig[0] = args->blk_sigset;
+		RT_SIGFRAME_UC(sigframe).uc_sigmask.sig[0] = args->blk_sigset;
 
 	restore_sched_info(&args->sp);
 	if (restore_fpu(sigframe, args))
@@ -189,6 +189,7 @@ long __export_restore_thread(struct thread_restore_args *args)
 
 	restore_creds(&args->ta->creds);
 
+	restore_tls(args->tls);
 
 	pr_info("%ld: Restored\n", sys_gettid());
 
@@ -197,7 +198,7 @@ long __export_restore_thread(struct thread_restore_args *args)
 
 	futex_dec_and_wake(&thread_inprogress);
 
-	new_sp = (long)rt_sigframe + 8;
+	new_sp = (long)rt_sigframe + SIGFRAME_OFFSET;
 	ARCH_RT_SIGRETURN(new_sp);
 
 core_restore_end:
@@ -399,6 +400,10 @@ long __export_restore_task(struct task_restore_core_args *args)
 			}
 		}
 
+		if (vma_entry->end >= TASK_SIZE) {
+			continue;
+		}
+
 		if (vma_entry->end > premmapped_end) {
 			if (vma_entry->start < premmapped_end)
 				addr = premmapped_end;
@@ -421,6 +426,10 @@ long __export_restore_task(struct task_restore_core_args *args)
 		if (!vma_priv(vma_entry))
 			continue;
 
+		if (vma_entry->end >= TASK_SIZE) {
+			continue;
+		}
+
 		if (vma_entry->start > vma_entry->shmid)
 			break;
 
@@ -438,6 +447,10 @@ long __export_restore_task(struct task_restore_core_args *args)
 		if (!vma_priv(vma_entry))
 			continue;
 
+		if (vma_entry->start > TASK_SIZE) {
+			continue;
+		}
+
 		if (vma_entry->start < vma_entry->shmid)
 			break;
 
@@ -684,14 +697,16 @@ long __export_restore_task(struct task_restore_core_args *args)
 
 	ret = sys_munmap(args->task_entries, TASK_ENTRIES_SIZE);
 	if (ret < 0) {
-		ret = ((long)__LINE__ << 32) | -ret;
+		ret = ((long)__LINE__ << 16) | ((-ret) & 0xffff);
 		goto core_restore_failed;
 	}
 
+	restore_tls(args->tls);
+
 	/*
 	 * Sigframe stack.
 	 */
-	new_sp = (long)rt_sigframe + 8;
+	new_sp = (long)rt_sigframe + SIGFRAME_OFFSET;
 
 	/*
 	 * Prepare the stack and call for sigreturn,
-- 
1.7.10.4