Re: nios2: is the ptrace ABI correct?

[Chung-Lin Tang <chunglin.tang@gmail.com>]

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On 2015/3/10 12:54 AM, Chung-Lin Tang wrote:
> It appears that some of the ways nios2 has organized the
> ucontext/pt_regs/etc. are remnants of the pre-generic code, some
> basically because the port was based off m68k.
> 
> I've re-organized the headers a bit: nios2/include/asm/ucontext.h is
> deleted, and re-definition of struct sigcontext now allows use of
> uapi/asm-generic/ucontext.h directly.  Note that the reorg, despite
> effectively renaming some fields, is still binary compatible. I'll
> probably update the corresponding glibc definitions later.
> 
> struct pt_regs is now not exported, and all exported register sets are
> now supposed to follow the 49 register set defined as in GDB now.
> 
> Tobias, Ley Foon, how do you think this looks?

Sorry, accidentally attached unrelated GCC patch instead, this one's the
correct one.

Chung-Lin


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diff --git a/arch/nios2/include/asm/ptrace.h b/arch/nios2/include/asm/ptrace.h
index 20fb1cf..6424621 100644
--- a/arch/nios2/include/asm/ptrace.h
+++ b/arch/nios2/include/asm/ptrace.h
@@ -15,7 +15,54 @@
 
 #include <uapi/asm/ptrace.h>
 
+/* This struct defines the way the registers are stored on the
+   stack during a system call.  */
+
 #ifndef __ASSEMBLY__
+struct pt_regs {
+	unsigned long  r8;	/* r8-r15 Caller-saved GP registers */
+	unsigned long  r9;
+	unsigned long  r10;
+	unsigned long  r11;
+	unsigned long  r12;
+	unsigned long  r13;
+	unsigned long  r14;
+	unsigned long  r15;
+	unsigned long  r1;	/* Assembler temporary */
+	unsigned long  r2;	/* Retval LS 32bits */
+	unsigned long  r3;	/* Retval MS 32bits */
+	unsigned long  r4;	/* r4-r7 Register arguments */
+	unsigned long  r5;
+	unsigned long  r6;
+	unsigned long  r7;
+	unsigned long  orig_r2;	/* Copy of r2 ?? */
+	unsigned long  ra;	/* Return address */
+	unsigned long  fp;	/* Frame pointer */
+	unsigned long  sp;	/* Stack pointer */
+	unsigned long  gp;	/* Global pointer */
+	unsigned long  estatus;
+	unsigned long  ea;	/* Exception return address (pc) */
+	unsigned long  orig_r7;
+};
+
+/*
+ * This is the extended stack used by signal handlers and the context
+ * switcher: it's pushed after the normal "struct pt_regs".
+ */
+struct switch_stack {
+	unsigned long  r16;	/* r16-r23 Callee-saved GP registers */
+	unsigned long  r17;
+	unsigned long  r18;
+	unsigned long  r19;
+	unsigned long  r20;
+	unsigned long  r21;
+	unsigned long  r22;
+	unsigned long  r23;
+	unsigned long  fp;
+	unsigned long  gp;
+	unsigned long  ra;
+};
+
 #define user_mode(regs)	(((regs)->estatus & ESTATUS_EU))
 
 #define instruction_pointer(regs)	((regs)->ra)
diff --git a/arch/nios2/include/asm/ucontext.h b/arch/nios2/include/asm/ucontext.h
deleted file mode 100644
index 2c87614..0000000
--- a/arch/nios2/include/asm/ucontext.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/*
- * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
- * Copyright (C) 2004 Microtronix Datacom Ltd
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- */
-
-#ifndef _ASM_NIOS2_UCONTEXT_H
-#define _ASM_NIOS2_UCONTEXT_H
-
-typedef int greg_t;
-#define NGREG 32
-typedef greg_t gregset_t[NGREG];
-
-struct mcontext {
-	int version;
-	gregset_t gregs;
-};
-
-#define MCONTEXT_VERSION 2
-
-struct ucontext {
-	unsigned long	  uc_flags;
-	struct ucontext  *uc_link;
-	stack_t		  uc_stack;
-	struct mcontext	  uc_mcontext;
-	sigset_t	  uc_sigmask;	/* mask last for extensibility */
-};
-
-#endif
diff --git a/arch/nios2/include/uapi/asm/Kbuild b/arch/nios2/include/uapi/asm/Kbuild
index 4f07ca3f8..37613119 100644
--- a/arch/nios2/include/uapi/asm/Kbuild
+++ b/arch/nios2/include/uapi/asm/Kbuild
@@ -2,3 +2,5 @@ include include/uapi/asm-generic/Kbuild.asm
 
 header-y += elf.h
 header-y += ucontext.h
+
+generic-y += ucontext.h
diff --git a/arch/nios2/include/uapi/asm/elf.h b/arch/nios2/include/uapi/asm/elf.h
index a5b91ae..6f06d3b 100644
--- a/arch/nios2/include/uapi/asm/elf.h
+++ b/arch/nios2/include/uapi/asm/elf.h
@@ -50,9 +50,7 @@
 
 typedef unsigned long elf_greg_t;
 
-#define ELF_NGREG	\
-	((sizeof(struct pt_regs) + sizeof(struct switch_stack)) /	\
-		sizeof(elf_greg_t))
+#define ELF_NGREG		49
 typedef elf_greg_t elf_gregset_t[ELF_NGREG];
 
 typedef unsigned long elf_fpregset_t;
diff --git a/arch/nios2/include/uapi/asm/ptrace.h b/arch/nios2/include/uapi/asm/ptrace.h
index e83a7c9..71a3305 100644
--- a/arch/nios2/include/uapi/asm/ptrace.h
+++ b/arch/nios2/include/uapi/asm/ptrace.h
@@ -67,53 +67,9 @@
 
 #define NUM_PTRACE_REG (PTR_TLBMISC + 1)
 
-/* this struct defines the way the registers are stored on the
-   stack during a system call.
-
-   There is a fake_regs in setup.c that has to match pt_regs.*/
-
-struct pt_regs {
-	unsigned long  r8;		/* r8-r15 Caller-saved GP registers */
-	unsigned long  r9;
-	unsigned long  r10;
-	unsigned long  r11;
-	unsigned long  r12;
-	unsigned long  r13;
-	unsigned long  r14;
-	unsigned long  r15;
-	unsigned long  r1;		/* Assembler temporary */
-	unsigned long  r2;		/* Retval LS 32bits */
-	unsigned long  r3;		/* Retval MS 32bits */
-	unsigned long  r4;		/* r4-r7 Register arguments */
-	unsigned long  r5;
-	unsigned long  r6;
-	unsigned long  r7;
-	unsigned long  orig_r2;		/* Copy of r2 ?? */
-	unsigned long  ra;		/* Return address */
-	unsigned long  fp;		/* Frame pointer */
-	unsigned long  sp;		/* Stack pointer */
-	unsigned long  gp;		/* Global pointer */
-	unsigned long  estatus;
-	unsigned long  ea;		/* Exception return address (pc) */
-	unsigned long  orig_r7;
-};
-
-/*
- * This is the extended stack used by signal handlers and the context
- * switcher: it's pushed after the normal "struct pt_regs".
- */
-struct switch_stack {
-	unsigned long  r16;		/* r16-r23 Callee-saved GP registers */
-	unsigned long  r17;
-	unsigned long  r18;
-	unsigned long  r19;
-	unsigned long  r20;
-	unsigned long  r21;
-	unsigned long  r22;
-	unsigned long  r23;
-	unsigned long  fp;
-	unsigned long  gp;
-	unsigned long  ra;
+/* User structures for general purpose registers.  */
+struct user_pt_regs {
+	__u32		regs[49];
 };
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/nios2/include/uapi/asm/sigcontext.h b/arch/nios2/include/uapi/asm/sigcontext.h
index 7b8bb41..b67944a 100644
--- a/arch/nios2/include/uapi/asm/sigcontext.h
+++ b/arch/nios2/include/uapi/asm/sigcontext.h
@@ -15,14 +15,16 @@
  * details.
  */
 
-#ifndef _ASM_NIOS2_SIGCONTEXT_H
-#define _ASM_NIOS2_SIGCONTEXT_H
+#ifndef _UAPI__ASM_SIGCONTEXT_H
+#define _UAPI__ASM_SIGCONTEXT_H
 
-#include <asm/ptrace.h>
+#include <linux/types.h>
+
+#define MCONTEXT_VERSION 2
 
 struct sigcontext {
-	struct pt_regs regs;
-	unsigned long  sc_mask;	/* old sigmask */
+	int version;
+	unsigned long gregs[32];
 };
 
 #endif
diff --git a/arch/nios2/kernel/signal.c b/arch/nios2/kernel/signal.c
index 2d0ea25..dda41e4 100644
--- a/arch/nios2/kernel/signal.c
+++ b/arch/nios2/kernel/signal.c
@@ -39,7 +39,7 @@ static inline int rt_restore_ucontext(struct pt_regs *regs,
 					struct ucontext *uc, int *pr2)
 {
 	int temp;
-	greg_t *gregs = uc->uc_mcontext.gregs;
+	unsigned long *gregs = uc->uc_mcontext.gregs;
 	int err;
 
 	/* Always make any pending restarted system calls return -EINTR */
@@ -127,7 +127,7 @@ badframe:
 static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
 {
 	struct switch_stack *sw = (struct switch_stack *)regs - 1;
-	greg_t *gregs = uc->uc_mcontext.gregs;
+	unsigned long *gregs = uc->uc_mcontext.gregs;
 	int err = 0;
 
 	err |= __put_user(MCONTEXT_VERSION, &uc->uc_mcontext.version);