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Message-Id: <20211019051716.4173-9-jcmvbkbc@gmail.com>
Date: Mon, 18 Oct 2021 22:17:14 -0700
From: Max Filippov <jcmvbkbc@...il.com>
To: linux-xtensa@...ux-xtensa.org
Cc: Chris Zankel <chris@...kel.net>, linux-kernel@...r.kernel.org,
Max Filippov <jcmvbkbc@...il.com>
Subject: [PATCH 08/10] xtensa: only build windowed register support code when needed
There's no need in window overflow/underflow/alloca exception handlers
or window spill code when neither kernel nor userspace support windowed
registers. Don't build or link it.
Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
---
arch/xtensa/include/asm/traps.h | 2 ++
arch/xtensa/kernel/entry.S | 5 ++++-
arch/xtensa/kernel/setup.c | 2 ++
arch/xtensa/kernel/signal.c | 12 ++++++++++--
arch/xtensa/kernel/traps.c | 2 ++
arch/xtensa/kernel/vectors.S | 15 +++++++++++++++
arch/xtensa/kernel/vmlinux.lds.S | 12 ++++++++++--
7 files changed, 45 insertions(+), 5 deletions(-)
diff --git a/arch/xtensa/include/asm/traps.h b/arch/xtensa/include/asm/traps.h
index f720a57d0a5b..6fa47cd8e02d 100644
--- a/arch/xtensa/include/asm/traps.h
+++ b/arch/xtensa/include/asm/traps.h
@@ -56,6 +56,7 @@ void secondary_trap_init(void);
static inline void spill_registers(void)
{
+#if defined(__XTENSA_WINDOWED_ABI__)
#if XCHAL_NUM_AREGS > 16
__asm__ __volatile__ (
" call8 1f\n"
@@ -96,6 +97,7 @@ static inline void spill_registers(void)
" mov a12, a12\n"
: : : "memory");
#endif
+#endif
}
struct debug_table {
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 8029ce24af92..99ab3c1a3387 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -969,6 +969,7 @@ ENDPROC(unrecoverable_exception)
__XTENSA_HANDLER
.literal_position
+#ifdef SUPPORT_WINDOWED
/*
* Fast-handler for alloca exceptions
*
@@ -1032,6 +1033,7 @@ ENTRY(fast_alloca)
8: j _WindowUnderflow8
4: j _WindowUnderflow4
ENDPROC(fast_alloca)
+#endif
#ifdef CONFIG_USER_ABI_CALL0_PROBE
/*
@@ -1228,7 +1230,8 @@ ENDPROC(fast_syscall_xtensa)
* Note: We assume the stack pointer is EXC_TABLE_KSTK in the fixup handler.
*/
-#ifdef CONFIG_FAST_SYSCALL_SPILL_REGISTERS
+#if defined(CONFIG_FAST_SYSCALL_SPILL_REGISTERS) && \
+ defined(USER_SUPPORT_WINDOWED)
ENTRY(fast_syscall_spill_registers)
diff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c
index ed184106e4cf..3638fb98a1ab 100644
--- a/arch/xtensa/kernel/setup.c
+++ b/arch/xtensa/kernel/setup.c
@@ -349,8 +349,10 @@ void __init setup_arch(char **cmdline_p)
#endif
#ifdef CONFIG_VECTORS_ADDR
+#ifdef SUPPORT_WINDOWED
mem_reserve(__pa(&_WindowVectors_text_start),
__pa(&_WindowVectors_text_end));
+#endif
mem_reserve(__pa(&_DebugInterruptVector_text_start),
__pa(&_DebugInterruptVector_text_end));
diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c
index c4d77dbfb61a..f6c949895b3e 100644
--- a/arch/xtensa/kernel/signal.c
+++ b/arch/xtensa/kernel/signal.c
@@ -45,12 +45,13 @@ struct rt_sigframe
unsigned int window[4];
};
-/*
+#if defined(USER_SUPPORT_WINDOWED)
+/*
* Flush register windows stored in pt_regs to stack.
* Returns 1 for errors.
*/
-int
+static int
flush_window_regs_user(struct pt_regs *regs)
{
const unsigned long ws = regs->windowstart;
@@ -121,6 +122,13 @@ flush_window_regs_user(struct pt_regs *regs)
errout:
return err;
}
+#else
+static int
+flush_window_regs_user(struct pt_regs *regs)
+{
+ return 0;
+}
+#endif
/*
* Note: We don't copy double exception 'regs', we have to finish double exc.
diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c
index 874b6efc6fb3..4418438b13e6 100644
--- a/arch/xtensa/kernel/traps.c
+++ b/arch/xtensa/kernel/traps.c
@@ -97,7 +97,9 @@ static dispatch_init_table_t __initdata dispatch_init_table[] = {
/* EXCCAUSE_INSTRUCTION_FETCH unhandled */
/* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
{ EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
+#ifdef SUPPORT_WINDOWED
{ EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
+#endif
/* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
/* EXCCAUSE_PRIVILEGED unhandled */
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
diff --git a/arch/xtensa/kernel/vectors.S b/arch/xtensa/kernel/vectors.S
index 0eed5aa82914..407ece204e7c 100644
--- a/arch/xtensa/kernel/vectors.S
+++ b/arch/xtensa/kernel/vectors.S
@@ -226,6 +226,7 @@ ENTRY(_DoubleExceptionVector)
xsr a0, depc # get DEPC, save a0
+#ifdef SUPPORT_WINDOWED
movi a2, WINDOW_VECTORS_VADDR
_bltu a0, a2, .Lfixup
addi a2, a2, WINDOW_VECTORS_SIZE
@@ -275,6 +276,10 @@ _DoubleExceptionVector_WindowUnderflow:
l32i a0, a0, EXC_TABLE_FAST_USER
jx a0
+#else
+ j .Lfixup
+#endif
+
/*
* We only allow the ITLB miss exception if we are in kernel space.
* All other exceptions are unexpected and thus unrecoverable!
@@ -343,6 +348,7 @@ _DoubleExceptionVector_WindowUnderflow:
l32i a0, a0, EXC_TABLE_FAST_USER
jx a0
+#ifdef SUPPORT_WINDOWED
/*
* Restart window OVERFLOW exception.
* Currently:
@@ -475,9 +481,12 @@ _DoubleExceptionVector_handle_exception:
rsr a0, depc
rotw -3
j 1b
+#endif
ENDPROC(_DoubleExceptionVector)
+#ifdef SUPPORT_WINDOWED
+
/*
* Fixup handler for TLB miss in double exception handler for window owerflow.
* We get here with windowbase set to the window that was being spilled and
@@ -590,6 +599,8 @@ ENTRY(window_overflow_restore_a0_fixup)
ENDPROC(window_overflow_restore_a0_fixup)
+#endif
+
/*
* Debug interrupt vector
*
@@ -687,6 +698,8 @@ _SimulateUserKernelVectorException:
.section .WindowVectors.text, "ax"
+#ifdef SUPPORT_WINDOWED
+
/* 4-Register Window Overflow Vector (Handler) */
ENTRY_ALIGN64(_WindowOverflow4)
@@ -787,4 +800,6 @@ ENTRY_ALIGN64(_WindowUnderflow12)
ENDPROC(_WindowUnderflow12)
+#endif
+
.text
diff --git a/arch/xtensa/kernel/vmlinux.lds.S b/arch/xtensa/kernel/vmlinux.lds.S
index d23a6e38f062..eee270a039a4 100644
--- a/arch/xtensa/kernel/vmlinux.lds.S
+++ b/arch/xtensa/kernel/vmlinux.lds.S
@@ -94,7 +94,9 @@ SECTIONS
. = ALIGN(PAGE_SIZE);
_vecbase = .;
+#ifdef SUPPORT_WINDOWED
SECTION_VECTOR2 (.WindowVectors.text, WINDOW_VECTORS_VADDR)
+#endif
#if XCHAL_EXCM_LEVEL >= 2
SECTION_VECTOR2 (.Level2InterruptVector.text, INTLEVEL2_VECTOR_VADDR)
#endif
@@ -166,8 +168,10 @@ SECTIONS
__boot_reloc_table_start = ABSOLUTE(.);
#if !MERGED_VECTORS
+#ifdef SUPPORT_WINDOWED
RELOCATE_ENTRY(_WindowVectors_text,
.WindowVectors.text);
+#endif
#if XCHAL_EXCM_LEVEL >= 2
RELOCATE_ENTRY(_Level2InterruptVector_text,
.Level2InterruptVector.text);
@@ -229,14 +233,18 @@ SECTIONS
#if !MERGED_VECTORS
/* The vectors are relocated to the real position at startup time */
+#ifdef SUPPORT_WINDOWED
SECTION_VECTOR4 (_WindowVectors_text,
.WindowVectors.text,
WINDOW_VECTORS_VADDR,
- .dummy)
+ LAST)
+#undef LAST
+#define LAST .WindowVectors.text
+#endif
SECTION_VECTOR4 (_DebugInterruptVector_text,
.DebugInterruptVector.text,
DEBUG_VECTOR_VADDR,
- .WindowVectors.text)
+ LAST)
#undef LAST
#define LAST .DebugInterruptVector.text
#if XCHAL_EXCM_LEVEL >= 2
--
2.20.1
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