ARC: Signal handling
Includes following fixes courtesy review by Al-Viro
* Tracer poke to Callee-regs were lost
Before going off into do_signal( ) we save the user-mode callee regs
(as they are not saved by default as part of pt_regs). This is to make
sure that that a Tracer (if tracing related signal) is able to do likes
of PEEKUSR(callee-reg).
However in return path we were simply discarding the user-mode callee
regs, which would break a POKEUSR(callee-reg) from a tracer.
* Issue related to multiple syscall restarts are addressed in next patch
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Acked-by: Jonas Bonn <jonas@southpole.se>
diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h
index 63705b1..6b42bf5 100644
--- a/arch/arc/include/asm/entry.h
+++ b/arch/arc/include/asm/entry.h
@@ -166,6 +166,41 @@
.endm
/*--------------------------------------------------------------
+ * RESTORE_CALLEE_SAVED_USER:
+ * This is called after do_signal where tracer might have changed callee regs
+ * thus we need to restore the reg file.
+ * Special case handling is required for r25 in case it is used by kernel
+ * for caching task ptr. Ptrace would have modified on-kernel-stack value of
+ * r25, which needs to be shoved back into task->thread.user_r25 where from
+ * Low level exception/ISR return code will retrieve to populate with rest of
+ * callee reg-file.
+ *-------------------------------------------------------------*/
+.macro RESTORE_CALLEE_SAVED_USER
+
+ add sp, sp, 4 /* skip "callee_regs->stack_place_holder" */
+
+#ifdef CONFIG_ARC_CURR_IN_REG
+ ld.ab r12, [sp, 4]
+ st r12, [r25, TASK_THREAD + THREAD_USER_R25]
+#else
+ ld.ab r25, [sp, 4]
+#endif
+
+ ld.ab r24, [sp, 4]
+ ld.ab r23, [sp, 4]
+ ld.ab r22, [sp, 4]
+ ld.ab r21, [sp, 4]
+ ld.ab r20, [sp, 4]
+ ld.ab r19, [sp, 4]
+ ld.ab r18, [sp, 4]
+ ld.ab r17, [sp, 4]
+ ld.ab r16, [sp, 4]
+ ld.ab r15, [sp, 4]
+ ld.ab r14, [sp, 4]
+ ld.ab r13, [sp, 4]
+.endm
+
+/*--------------------------------------------------------------
* Super FAST Restore callee saved regs by simply re-adjusting SP
*-------------------------------------------------------------*/
.macro DISCARD_CALLEE_SAVED_USER
diff --git a/arch/arc/include/asm/sigcontext.h b/arch/arc/include/asm/sigcontext.h
new file mode 100644
index 0000000..9678a11
--- /dev/null
+++ b/arch/arc/include/asm/sigcontext.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_ARC_SIGCONTEXT_H
+#define _ASM_ARC_SIGCONTEXT_H
+
+#include <asm/ptrace.h>
+
+/*
+ * Signal context structure - contains all info to do with the state
+ * before the signal handler was invoked.
+ */
+struct sigcontext {
+ struct user_regs_struct regs;
+};
+
+#endif /* _ASM_ARC_SIGCONTEXT_H */
diff --git a/arch/arc/include/asm/signal.h b/arch/arc/include/asm/signal.h
new file mode 100644
index 0000000..fad62f7
--- /dev/null
+++ b/arch/arc/include/asm/signal.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Amit Bhor, Sameer Dhavale: Codito Technologies 2004
+ */
+
+#ifndef _ASM_ARC_SIGNAL_H
+#define _ASM_ARC_SIGNAL_H
+
+/*
+ * This is much needed for ARC sigreturn optimization.
+ * This allows uClibc to piggback the addr of a sigreturn stub in sigaction,
+ * which allows sigreturn based re-entry into kernel after handling signal.
+ * W/o this kernel needs to "synthesize" the sigreturn trampoline on user
+ * mode stack which in turn forces the following:
+ * -TLB Flush (after making the stack page executable)
+ * -Cache line Flush (to make I/D Cache lines coherent)
+ */
+#define SA_RESTORER 0x04000000
+
+#include <asm-generic/signal.h>
+
+#endif /* _ASM_ARC_SIGNAL_H */