[PATCH v2] MIPS: Exclude more dsemul code when CONFIG_MIPS_FP_SUPPORT=n

[PATCH v2] MIPS: Exclude more dsemul code when CONFIG_MIPS_FP_SUPPORT=n

[Yousong Zhou]

This furthers what commit 42b10815d559 ("MIPS: Don't compile math-emu
when CONFIG_MIPS_FP_SUPPORT=n") has done

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
---
v2 <- v1: Fix using unknown symbol CONFIG_MIPS_FP_EMULATOR, @tsbogend

 arch/mips/include/asm/processor.h | 12 ++++++------
 arch/mips/kernel/process.c        | 10 ++++++++--
 arch/mips/kernel/vdso.c           | 26 +++++++++++++++-----------
 3 files changed, 29 insertions(+), 19 deletions(-)

diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h
index 7619ad319400..813ba94d87bb 100644
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -253,13 +253,13 @@ struct thread_struct {
 #ifdef CONFIG_MIPS_FP_SUPPORT
 	/* Saved fpu/fpu emulator stuff. */
 	struct mips_fpu_struct fpu FPU_ALIGN;
-#endif
 	/* Assigned branch delay slot 'emulation' frame */
 	atomic_t bd_emu_frame;
 	/* PC of the branch from a branch delay slot 'emulation' */
 	unsigned long bd_emu_branch_pc;
 	/* PC to continue from following a branch delay slot 'emulation' */
 	unsigned long bd_emu_cont_pc;
+#endif
 #ifdef CONFIG_MIPS_MT_FPAFF
 	/* Emulated instruction count */
 	unsigned long emulated_fp;
@@ -302,7 +302,11 @@ struct thread_struct {
 		.fpr		= {{{0,},},},			\
 		.fcr31		= 0,				\
 		.msacsr		= 0,				\
-	},
+	},							\
+	/* Delay slot emulation */				\
+	.bd_emu_frame = ATOMIC_INIT(BD_EMUFRAME_NONE),		\
+	.bd_emu_branch_pc = 0,					\
+	.bd_emu_cont_pc = 0,
 #else
 # define FPU_INIT
 #endif
@@ -334,10 +338,6 @@ struct thread_struct {
 	 * FPU affinity state (null if not FPAFF)		\
 	 */							\
 	FPAFF_INIT						\
-	/* Delay slot emulation */				\
-	.bd_emu_frame = ATOMIC_INIT(BD_EMUFRAME_NONE),		\
-	.bd_emu_branch_pc = 0,					\
-	.bd_emu_cont_pc = 0,					\
 	/*							\
 	 * Saved DSP stuff					\
 	 */							\
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 339870ed92f7..b2a797557825 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -75,7 +75,9 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 	lose_fpu(0);
 	clear_thread_flag(TIF_MSA_CTX_LIVE);
 	clear_used_math();
+#ifdef CONFIG_MIPS_FP_SUPPORT
 	atomic_set(&current->thread.bd_emu_frame, BD_EMUFRAME_NONE);
+#endif
 	init_dsp();
 	regs->cp0_epc = pc;
 	regs->regs[29] = sp;
@@ -176,7 +178,9 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
 	clear_tsk_thread_flag(p, TIF_FPUBOUND);
 #endif /* CONFIG_MIPS_MT_FPAFF */
 
+#ifdef CONFIG_MIPS_FP_SUPPORT
 	atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
+#endif
 
 	if (clone_flags & CLONE_SETTLS)
 		ti->tp_value = tls;
@@ -650,8 +654,10 @@ unsigned long mips_stack_top(void)
 {
 	unsigned long top = TASK_SIZE & PAGE_MASK;
 
-	/* One page for branch delay slot "emulation" */
-	top -= PAGE_SIZE;
+	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
+		/* One page for branch delay slot "emulation" */
+		top -= PAGE_SIZE;
+	}
 
 	/* Space for the VDSO, data page & GIC user page */
 	top -= PAGE_ALIGN(current->thread.abi->vdso->size);
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
index bc35f8499111..3adb7354bc01 100644
--- a/arch/mips/kernel/vdso.c
+++ b/arch/mips/kernel/vdso.c
@@ -71,10 +71,12 @@ subsys_initcall(init_vdso);
 
 static unsigned long vdso_base(void)
 {
-	unsigned long base;
+	unsigned long base = STACK_TOP;
 
-	/* Skip the delay slot emulation page */
-	base = STACK_TOP + PAGE_SIZE;
+	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
+		/* Skip the delay slot emulation page */
+		base += PAGE_SIZE;
+	}
 
 	if (current->flags & PF_RANDOMIZE) {
 		base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1);
@@ -95,14 +97,16 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	if (down_write_killable(&mm->mmap_sem))
 		return -EINTR;
 
-	/* Map delay slot emulation page */
-	base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
-			   VM_READ | VM_EXEC |
-			   VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
-			   0, NULL);
-	if (IS_ERR_VALUE(base)) {
-		ret = base;
-		goto out;
+	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
+		/* Map delay slot emulation page */
+		base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
+				VM_READ | VM_EXEC |
+				VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
+				0, NULL);
+		if (IS_ERR_VALUE(base)) {
+			ret = base;
+			goto out;
+		}
 	}
 
 	/*

Re: [PATCH v2] MIPS: Exclude more dsemul code when CONFIG_MIPS_FP_SUPPORT=n

[Thomas Bogendoerfer]

On Tue, Mar 24, 2020 at 11:27:51PM +0800, Yousong Zhou wrote:
> This furthers what commit 42b10815d559 ("MIPS: Don't compile math-emu
> when CONFIG_MIPS_FP_SUPPORT=n") has done
> 
> Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
> ---
> v2 <- v1: Fix using unknown symbol CONFIG_MIPS_FP_EMULATOR, @tsbogend
> 
>  arch/mips/include/asm/processor.h | 12 ++++++------
>  arch/mips/kernel/process.c        | 10 ++++++++--
>  arch/mips/kernel/vdso.c           | 26 +++++++++++++++-----------
>  3 files changed, 29 insertions(+), 19 deletions(-)

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]