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List:       linux-parisc
Subject:    [PATCH] parisc: ptraced 64-bit binary should call 64-bit syscalls
From:       Helge Deller <deller () gmx ! de>
Date:       2018-08-16 20:33:04
Message-ID: 20180816203304.GA17541 () p100 ! box
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Fix the strace code path to call 64-bit syscalls in case we were called
by a 64-bit process.

Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 4886a6d..dec27d8 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -331,8 +327,6 @@ tracesys_next:
 	 *  task->thread.regs.gr[20] above.
 	 */
 	copy	%ret0,%r20
-	ldil	L%sys_call_table,%r1
-	ldo     R%sys_call_table(%r1), %r19
 
 	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
 	LDREG	TI_TASK(%r1), %r1
@@ -354,6 +348,24 @@ tracesys_next:
 	comiclr,>>	__NR_Linux_syscalls, %r20, %r0
 	b,n	.Ltracesys_nosys
 
+	/* Note!  We cannot use the syscall table that is mapped
+	nearby since the gateway page is mapped execute-only. */
+
+#ifdef CONFIG_64BIT
+	LDREG	TASK_PT_GR30(%r1), %r19		/* get users sp back */
+	extrd,u	%r19,63,1,%r2			/* W hidden in bottom bit */
+
+	ldil	L%sys_call_table, %r1
+	or,=	%r2,%r2,%r2
+	addil	L%(sys_call_table64-sys_call_table), %r1
+	ldo	R%sys_call_table(%r1), %r19
+	or,=	%r2,%r2,%r2
+	ldo	R%sys_call_table64(%r1), %r19
+#else
+	ldil	L%sys_call_table, %r1
+	ldo     R%sys_call_table(%r1), %r19
+#endif
+
 	LDREGX  %r20(%r19), %r19
 
 	/* If this is a sys_rt_sigreturn call, and the signal was received
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