[regression fix] Re: "sh: convert to ->regset_get()" breaks linux-sh build

[Al Viro <viro@zeniv.linux.org.uk>]

On Sun, Aug 09, 2020 at 05:14:38PM +0100, Al Viro wrote:

> What the... oh, I see.
> 
> Commit in the regset followup series has fixed that, with bisect hazard unnoticed.
> And since only the followups have not gone in, bisect hazard has turned into
> a mainline breakage ;/
> 
> Sorry about that.  FWIW, the commit in question is this; all per-architecture
> parts in it are mutually independent, but I'll probably just send this one
> to Linus - no point splitting it up.

FWIW, there are several ways to handle that.  One is to pull vfs.git#fixes -
that's the first commit of #regset.followups.  Another is to cherry-pick
the same.  And the minimal fix would be the subset of that commit as below.
Linus, what would you prefer?

sh: kill unused dump_fpu() instance

dead code now that fdpic has switched to regset coredumps.
 
Fixes: 3399d90ce63e "sh: convert to ->regset_get()"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
diff --git a/arch/sh/include/asm/fpu.h b/arch/sh/include/asm/fpu.h
index 43cfaf929aa7..04584be8986c 100644
--- a/arch/sh/include/asm/fpu.h
+++ b/arch/sh/include/asm/fpu.h
@@ -37,11 +37,6 @@ struct user_regset;
 extern int do_fpu_inst(unsigned short, struct pt_regs *);
 extern int init_fpu(struct task_struct *);
 
-extern int fpregs_get(struct task_struct *target,
-		      const struct user_regset *regset,
-		      unsigned int pos, unsigned int count,
-		      void *kbuf, void __user *ubuf);
-
 static inline void __unlazy_fpu(struct task_struct *tsk, struct pt_regs *regs)
 {
 	if (task_thread_info(tsk)->status & TS_USEDFPU) {
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index 6ab397bc47ed..7a59a63560c5 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -93,24 +93,6 @@ void release_thread(struct task_struct *dead_task)
 	/* do nothing */
 }
 
-/* Fill in the fpu structure for a core dump.. */
-int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
-{
-	int fpvalid = 0;
-
-#if defined(CONFIG_SH_FPU)
-	struct task_struct *tsk = current;
-
-	fpvalid = !!tsk_used_math(tsk);
-	if (fpvalid)
-		fpvalid = !fpregs_get(tsk, NULL,
-				      (struct membuf){fpu, sizeof(*fpu)});
-#endif
-
-	return fpvalid;
-}
-EXPORT_SYMBOL(dump_fpu);
-
 asmlinkage void ret_from_fork(void);
 asmlinkage void ret_from_kernel_thread(void);
 
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 5c93bdb6c41a..609b7c917e6e 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -165,7 +165,7 @@ static int genregs_set(struct task_struct *target,
 }
 
 #ifdef CONFIG_SH_FPU
-int fpregs_get(struct task_struct *target,
+static int fpregs_get(struct task_struct *target,
 	       const struct user_regset *regset,
 	       struct membuf to)
 {