[U-Boot] [PATCH v2] x86: Add 64-bit setjmp/longjmp implementation

[Heinrich Schuchardt]

On 06/06/2018 08:28 PM, Ivan Gorinov wrote:
> Add setjmp/longjmp functions for x86_64.
> The FPU control word and MXCSR control bits are preserved across calls.

With this patch

make mrproper && make qemu-x86_64_defconfig && make -j6

produces

arch/x86/cpu/built-in.o: In function `car_init':
arch/x86/cpu/qemu/car.S:25: undefined reference to `car_init_ret'

The error does not occur without this patch.

The missing symbol is defined in
arch/x86/cpu/start.S:98:car_init_ret:
but it is not defined in
arch/x86/cpu/start64.S

The following patch helps:

[PATCH 1/1] x86: qemu: do not build car.o with start64.o
https://lists.denx.de/pipermail/u-boot/2018-June/331440.html

But bootefi selftest with your patch leads to an immediate reset of the
qemu-x86_64 board.

Best regards

Heinrich

> 
> Signed-off-by: Ivan Gorinov <ivan.gorinov at intel.com>
> ---
>  arch/x86/cpu/x86_64/setjmp.S  | 66 +++++++++++++++++++++++++++++++++++++++++++
>  arch/x86/cpu/x86_64/setjmp.c  | 19 -------------
>  arch/x86/include/asm/setjmp.h | 19 +++++++++++++
>  3 files changed, 85 insertions(+), 19 deletions(-)
>  create mode 100644 arch/x86/cpu/x86_64/setjmp.S
>  delete mode 100644 arch/x86/cpu/x86_64/setjmp.c
> 
> diff --git a/arch/x86/cpu/x86_64/setjmp.S b/arch/x86/cpu/x86_64/setjmp.S
> new file mode 100644
> index 0000000..ef61a4a
> --- /dev/null
> +++ b/arch/x86/cpu/x86_64/setjmp.S
> @@ -0,0 +1,66 @@
> +/*
> + * Copyright (C) 2018 Intel Corporation
> + *
> + * SPDX-License-Identifier: GPL-2.0+
> + *
> + * See arch/x86/include/asm/setjmp.h for jmp_buf format
> + */
> +
> +#include <linux/linkage.h>
> +
> +.text
> +.align 8
> +
> +ENTRY(setjmp)
> +
> +	pop	%rcx
> +	movq	%rcx, (%rdi)	/* Return address */
> +	movq	%rsp, 8 (%rdi)
> +	movq	%rbp, 16 (%rdi)
> +	movq	%rbx, 24 (%rdi)
> +	movq	%r12, 32 (%rdi)
> +	movq	%r13, 40 (%rdi)
> +	movq	%r14, 48 (%rdi)
> +	movq	%r15, 56 (%rdi)
> +	fnstcw	64 (%rdi)
> +	stmxcsr	68 (%rdi)
> +	xorq	%rax, %rax	/* Direct invocation returns 0 */
> +	jmpq	*%rcx
> +
> +ENDPROC(setjmp)
> +
> +.align 8
> +
> +ENTRY(longjmp)
> +
> +	subq	$8, %rsp
> +
> +/* Restore the control bits of MXCSR */
> +
> +	stmxcsr	(%rsp)
> +	movl	$0x3f, %eax
> +	andl	%eax, (%rsp)
> +	notl	%eax
> +	andl	68 (%rdi), %eax
> +	orl	%eax, (%rsp)
> +	ldmxcsr	(%rsp)
> +
> +	fldcw	64 (%rdi)
> +
> +	movq	(%rdi), %rcx	/* Return address */
> +	movq	8 (%rdi), %rsp
> +	movq	16 (%rdi), %rbp
> +	movq	24 (%rdi), %rbx
> +	movq	32 (%rdi), %r12
> +	movq	40 (%rdi), %r13
> +	movq	48 (%rdi), %r14
> +	movq	56 (%rdi), %r15
> +
> +	movq	%rsi, %rax	/* Value to be returned by setjmp() */
> +	testq	%rax, %rax	/* cannot be 0 in this case */
> +	jnz	1f
> +	incq	%rax		/* Return 1 instead */
> +1:
> +	jmpq	*%rcx
> +
> +ENDPROC(longjmp)
> diff --git a/arch/x86/cpu/x86_64/setjmp.c b/arch/x86/cpu/x86_64/setjmp.c
> deleted file mode 100644
> index 5d4a74a..0000000
> --- a/arch/x86/cpu/x86_64/setjmp.c
> +++ /dev/null
> @@ -1,19 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0+
> -/*
> - * Copyright (c) 2016 Google, Inc
> - */
> -
> -#include <common.h>
> -#include <asm/setjmp.h>
> -
> -int setjmp(struct jmp_buf_data *jmp_buf)
> -{
> -	printf("WARNING: setjmp() is not supported\n");
> -
> -	return 0;
> -}
> -
> -void longjmp(struct jmp_buf_data *jmp_buf, int val)
> -{
> -	printf("WARNING: longjmp() is not supported\n");
> -}
> diff --git a/arch/x86/include/asm/setjmp.h b/arch/x86/include/asm/setjmp.h
> index f25975f..eae33fb 100644
> --- a/arch/x86/include/asm/setjmp.h
> +++ b/arch/x86/include/asm/setjmp.h
> @@ -8,6 +8,23 @@
>  #ifndef __setjmp_h
>  #define __setjmp_h
>  
> +#ifdef CONFIG_X86_64
> +
> +struct jmp_buf_data {
> +	unsigned long __rip;
> +	unsigned long __rsp;
> +	unsigned long __rbp;
> +	unsigned long __rbx;
> +	unsigned long __r12;
> +	unsigned long __r13;
> +	unsigned long __r14;
> +	unsigned long __r15;
> +	unsigned int __fcw;
> +	unsigned int __mxcsr;
> +};
> +
> +#else
> +
>  struct jmp_buf_data {
>  	unsigned int __ebx;
>  	unsigned int __esp;
> @@ -17,6 +34,8 @@ struct jmp_buf_data {
>  	unsigned int __eip;
>  };
>  
> +#endif
> +
>  int setjmp(struct jmp_buf_data *jmp_buf);
>  void longjmp(struct jmp_buf_data *jmp_buf, int val);
>  
>