[CRIU] [PATCH 1/2] ia32: Get rid of R_X86_64_32S relocation

[Dmitry Safonov]

Distributions starts to supply GCC that is configured to compile
-pie and -fPIC code by default due to security reasons.

CONFIG_COMPAT was unfriendy to -pie by the reason of R_X86_64_32S
relocation in call32.S helper:
  LINK     criu/criu
/usr/bin/ld: criu/arch/x86/crtools.built-in.o: relocation R_X86_64_32S against `.text' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Nonrepresentable section on output
collect2: error: ld returned 1 exit status
make[1]: *** [criu/Makefile:92: criu/criu] Error 1
make: *** [Makefile:225: criu] Error 2

Use %rip-relative addressing to avoid ld errors for shared binary linking.
Puff, all needs to be done with bare hands!

Now CONFIG_COMPAT can be used with -pie binaries and all should
also work for debian toolchain (#315).

Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
---
 criu/arch/x86/call32.S    | 20 ++++++++++++++------
 scripts/feature-tests.mak | 25 +++++++++++++++++++------
 2 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/criu/arch/x86/call32.S b/criu/arch/x86/call32.S
index dbed5dec3a9f..c2ddd9fc2682 100644
--- a/criu/arch/x86/call32.S
+++ b/criu/arch/x86/call32.S
@@ -39,19 +39,27 @@ ENTRY(call32_from_64)
 	mov %rsp,(%rdi)
 	mov %rdi,%rsp
 
+	/* Push return address and 64-bit segment descriptor */
+	sub $4, %rsp
+	movl $__USER_CS,(%rsp)
+	sub $4, %rsp
+	/* Using rip-relative addressing to get rid of R_X86_64_32S relocs */
+	leaq 2f(%rip),%r12
+	movl %r12d,(%rsp)
+
 	/* Switch into compatibility mode */
 	pushq $__USER32_CS
-	pushq $1f
+	/* Using rip-relative addressing to get rid of R_X86_64_32S relocs */
+	leaq 1f(%rip), %r12
+	pushq %r12
 	lretq
 
-1:
-	.code32
+1:	.code32
 	/* Run function and switch back */
 	call *%esi
-	jmp $__USER_CS,$1f
-	.code64
+	lret
 
-1:
+2:	.code64
 	/* Restore the stack */
 	mov (%rsp),%rsp
 	add $8, %rdi
diff --git a/scripts/feature-tests.mak b/scripts/feature-tests.mak
index 12bf5418102c..e39d97bb113e 100644
--- a/scripts/feature-tests.mak
+++ b/scripts/feature-tests.mak
@@ -106,17 +106,30 @@ define FEATURE_TEST_X86_COMPAT
         .text
 
 ENTRY(call32_from_64)
+        /* Push return address and 64-bit segment descriptor */
+        sub \$$4, %rsp
+        movl \$$__USER_CS,(%rsp)
+        sub \$$4, %rsp
+        /* Using rip-relative addressing to get rid of R_X86_64_32S relocs */
+        leaq 2f(%rip),%r12
+        movl %r12d,(%rsp)
+
         /* Switch into compatibility mode */
         pushq \$$__USER32_CS
-        pushq \$$1f
+        /* Using rip-relative addressing to get rid of R_X86_64_32S relocs */
+        leaq 1f(%rip), %r12
+        pushq %r12
         lretq
-1:
-        .code32
+
+1:	.code32
         /* Run function and switch back */
         call *%esi
-        jmp \$$__USER_CS,\$$1f
-        .code64
-1:
+        lret
+
+2:	.code64
+        /* Restore the stack */
+        mov (%rsp),%rsp
+        add \$$8, %rdi
 END(call32_from_64)
 
 ENTRY(main)
-- 
2.13.3