linux-kernel - [PATCH 4/5] openrisc: Add FPU config

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Message-ID: <20240411180644.2023991-5-shorne@gmail.com>
Date: Thu, 11 Apr 2024 19:06:31 +0100
From: Stafford Horne <shorne@...il.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Linux OpenRISC <linux-openrisc@...r.kernel.org>,
	Stafford Horne <shorne@...il.com>,
	Jonas Bonn <jonas@...thpole.se>,
	Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
	Oleg Nesterov <oleg@...hat.com>
Subject: [PATCH 4/5] openrisc: Add FPU config

Allow disabling FPU related code sequences to save space.

Signed-off-by: Stafford Horne <shorne@...il.com>
---
 arch/openrisc/Kconfig         | 9 +++++++++
 arch/openrisc/kernel/ptrace.c | 6 ++++++
 arch/openrisc/kernel/traps.c  | 3 ++-
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 3586cda55bde..69c0258700b2 100644
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -188,6 +188,15 @@ config SMP
 
 	  If you don't know what to do here, say N.
 
+config FPU
+	bool "FPU support"
+	default y
+	help
+	  Say N here if you want to disable all floating-point related procedures
+	  in the kernel and reduce binary size.
+
+	  If you don't know what to do here, say Y.
+
 source "kernel/Kconfig.hz"
 
 config OPENRISC_NO_SPR_SR_DSX
diff --git a/arch/openrisc/kernel/ptrace.c b/arch/openrisc/kernel/ptrace.c
index 1eeac3b62e9d..cf410193095f 100644
--- a/arch/openrisc/kernel/ptrace.c
+++ b/arch/openrisc/kernel/ptrace.c
@@ -88,6 +88,7 @@ static int genregs_set(struct task_struct *target,
 	return ret;
 }
 
+#ifdef CONFIG_FPU
 /*
  * As OpenRISC shares GPRs and floating point registers we don't need to export
  * the floating point registers again.  So here we only export the fpcsr special
@@ -115,13 +116,16 @@ static int fpregs_set(struct task_struct *target,
 				 &regs->fpcsr, 0, 4);
 	return ret;
 }
+#endif
 
 /*
  * Define the register sets available on OpenRISC under Linux
  */
 enum or1k_regset {
 	REGSET_GENERAL,
+#ifdef CONFIG_FPU
 	REGSET_FPU,
+#endif
 };
 
 static const struct user_regset or1k_regsets[] = {
@@ -133,6 +137,7 @@ static const struct user_regset or1k_regsets[] = {
 			    .regset_get = genregs_get,
 			    .set = genregs_set,
 			    },
+#ifdef CONFIG_FPU
 	[REGSET_FPU] = {
 			    .core_note_type = NT_PRFPREG,
 			    .n = sizeof(struct __or1k_fpu_state) / sizeof(long),
@@ -141,6 +146,7 @@ static const struct user_regset or1k_regsets[] = {
 			    .regset_get = fpregs_get,
 			    .set = fpregs_set,
 			    },
+#endif
 };
 
 static const struct user_regset_view user_or1k_native_view = {
diff --git a/arch/openrisc/kernel/traps.c b/arch/openrisc/kernel/traps.c
index 211ddaa0c5fa..57e0d674eb04 100644
--- a/arch/openrisc/kernel/traps.c
+++ b/arch/openrisc/kernel/traps.c
@@ -182,6 +182,7 @@ asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address)
 {
 	if (user_mode(regs)) {
 		int code = FPE_FLTUNK;
+#ifdef CONFIG_FPU
 		unsigned long fpcsr = regs->fpcsr;
 
 		if (fpcsr & SPR_FPCSR_IVF)
@@ -197,7 +198,7 @@ asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address)
 
 		/* Clear all flags */
 		regs->fpcsr &= ~SPR_FPCSR_ALLF;
-
+#endif
 		force_sig_fault(SIGFPE, code, (void __user *)regs->pc);
 	} else {
 		pr_emerg("KERNEL: Illegal fpe exception 0x%.8lx\n", regs->pc);
-- 
2.44.0