[ARM] 3110/5: old ABI compat: multi-ABI syscall entry support
Patch from Nicolas Pitre
This patch adds the required code to support both user space ABIs at
the same time. A second syscall table is created to include legacy ABI
syscalls that need an ABI compat wrapper.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 59ce1bc..8826d98 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -123,23 +123,49 @@
/*
* Get the system call number.
*/
-#if defined(CONFIG_AEABI)
- @ syscall number is in scno (r7) already.
+#if defined(CONFIG_OABI_COMPAT)
+ /*
+ * If we have CONFIG_OABI_COMPAT then we need to look at the swi
+ * value to determine if it is an EABI or an old ABI call.
+ */
+#ifdef CONFIG_ARM_THUMB
+ tst r8, #PSR_T_BIT
+ movne r10, #0 @ no thumb OABI emulation
+ ldreq r10, [lr, #-4] @ get SWI instruction
+#else
+ ldr r10, [lr, #-4] @ get SWI instruction
+ A710( and ip, r10, #0x0f000000 @ check for SWI )
+ A710( teq ip, #0x0f000000 )
+ A710( bne .Larm710bug )
+#endif
+
+#elif defined(CONFIG_AEABI)
+
+ /*
+ * Pure EABI user space always put syscall number into scno (r7).
+ */
A710( ldr ip, [lr, #-4] @ get SWI instruction )
A710( and ip, ip, #0x0f000000 @ check for SWI )
A710( teq ip, #0x0f000000 )
A710( bne .Larm710bug )
+
#elif defined(CONFIG_ARM_THUMB)
+
+ /* Legacy ABI only, possibly thumb mode. */
tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
ldreq scno, [lr, #-4]
+
#else
+
+ /* Legacy ABI only. */
ldr scno, [lr, #-4] @ get SWI instruction
A710( and ip, scno, #0x0f000000 @ check for SWI )
A710( teq ip, #0x0f000000 )
A710( bne .Larm710bug )
+
#endif
#ifdef CONFIG_ALIGNMENT_TRAP
@@ -150,12 +176,24 @@
enable_irq
get_thread_info tsk
+ adr tbl, sys_call_table @ load syscall table pointer
ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing
-#ifndef CONFIG_AEABI
+
+#if defined(CONFIG_OABI_COMPAT)
+ /*
+ * If the swi argument is zero, this is an EABI call and we do nothing.
+ *
+ * If this is an old ABI call, get the syscall number into scno and
+ * get the old ABI syscall table address.
+ */
+ bics r10, r10, #0xff000000
+ eorne scno, r10, #__NR_OABI_SYSCALL_BASE
+ ldrne tbl, =sys_oabi_call_table
+#elif !defined(CONFIG_AEABI)
bic scno, scno, #0xff000000 @ mask off SWI op-code
eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
#endif
- adr tbl, sys_call_table @ load syscall table pointer
+
stmdb sp!, {r4, r5} @ push fifth and sixth args
tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
bne __sys_trace
@@ -200,10 +238,24 @@
__cr_alignment:
.word cr_alignment
#endif
+ .ltorg
+
+/*
+ * This is the syscall table declaration for native ABI syscalls.
+ * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
+ */
+#define ABI(native, compat) native
+#ifdef CONFIG_AEABI
+#define OBSOLETE(syscall) sys_ni_syscall
+#else
+#define OBSOLETE(syscall) syscall
+#endif
.type sys_call_table, #object
ENTRY(sys_call_table)
#include "calls.S"
+#undef ABI
+#undef OBSOLETE
/*============================================================================
* Special system call wrappers
@@ -212,8 +264,7 @@
@ r8 = syscall table
.type sys_syscall, #function
sys_syscall:
-#ifndef CONFIG_AEABI
- eor scno, r0, #__NR_SYSCALL_BASE
+ eor scno, r0, #__NR_OABI_SYSCALL_BASE
cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
cmpne scno, #NR_syscalls @ check range
stmloia sp, {r5, r6} @ shuffle args
@@ -222,7 +273,6 @@
movlo r2, r3
movlo r3, r4
ldrlo pc, [tbl, scno, lsl #2]
-#endif
b sys_ni_syscall
sys_fork_wrapper:
@@ -290,6 +340,7 @@
#endif
#ifdef CONFIG_OABI_COMPAT
+
/*
* These are syscalls with argument register differences
*/
@@ -318,5 +369,18 @@
mov r2, r1
b sys_readahead
+/*
+ * Let's declare a second syscall table for old ABI binaries
+ * using the compatibility syscall entries.
+ */
+#define ABI(native, compat) compat
+#define OBSOLETE(syscall) syscall
+
+ .type sys_oabi_call_table, #object
+ENTRY(sys_oabi_call_table)
+#include "calls.S"
+#undef ABI
+#undef OBSOLETE
+
#endif