x86: Add 64-bit setjmp/longjmp implementation

Add setjmp/longjmp functions for x86_64,
based on existing 32-bit implementation.

Signed-off-by Ivan Gorinov <[email protected]>

---
 arch/x86/cpu/x86_64/setjmp.S  | 56 +++++++++++++++++++++++++++++++++++++++++++
 arch/x86/cpu/x86_64/setjmp.c  | 19 ---------------
 arch/x86/include/asm/setjmp.h | 17 +++++++++++++
 3 files changed, 73 insertions(+), 19 deletions(-)
 create mode 100644 arch/x86/cpu/x86_64/setjmp.S
 delete mode 100644 arch/x86/cpu/x86_64/setjmp.c

arch/x86/cpu/x86_64/setjmp.S new file +56 -0

new file mode 100644
index 0000000..e10ee49
@@ -0,0 +1,56 @@
+/*
+ * Based on arch/x86/cpu/i386/setjmp.S by H. Peter Anvin <[email protected]>
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+/*
+ * The jmp_buf is assumed to contain the following, in order:
+ *	<return address>
+ *	%rsp
+ *	%rbp
+ *	%rbx
+ *	%r12
+ *	%r13
+ *	%r14
+ *	%r15
+ */
+
+.text
+.align 8
+.globl	setjmp
+.type setjmp, @function
+
+setjmp:
+	pop	%rcx
+	movq	%rcx, (%rdi)	/* Return address */
+	movq	%rsp, 8 (%rdi)	/* Post-return %rsp! */
+	movq	%rbp, 16 (%rdi)
+	movq	%rbx, 24 (%rdi)
+	movq	%r12, 32 (%rdi)
+	movq	%r13, 40 (%rdi)
+	movq	%r14, 48 (%rdi)
+	movq	%r15, 56 (%rdi)
+	xorq	%rax, %rax	/* Return value */
+	jmpq	*%rcx
+
+/* Provide function size if needed */
+.size setjmp, .-setjmp
+
+.align 8
+.globl longjmp
+.type longjmp, @function
+
+longjmp:
+	movq	32 (%rdi), %r12
+	movq	40 (%rdi), %r13
+	movq	48 (%rdi), %r14
+	movq	56 (%rdi), %r15
+	movq	16 (%rdi), %rbp
+	movq	24 (%rdi), %rbx
+	movq	8 (%rdi), %rsp
+	movq	(%rdi), %rcx
+	movq	%rsi, %rdi
+	jmpq	*%rcx
+
+	.size longjmp, .-longjmp

arch/x86/cpu/x86_64/setjmp.c deleted +0 -19

deleted file mode 100644
index 5d4a74a..0000000
@@ -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");
-}

arch/x86/include/asm/setjmp.h +17 -0

index f25975f..49c36c1 100644
@@ -8,6 +8,21 @@
 #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;
+};
+
+#else
+
 struct jmp_buf_data {
 	unsigned int __ebx;
 	unsigned int __esp;

@@ -17,6 +32,8 @@ 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);
 

Quoted 2 lines · Ivan Gorinov

Add setjmp/longjmp functions for x86_64,
based on existing 32-bit implementation.

Thank you for your patch. This addresses a gap that really should be closed.

Please, add a line to the commit message indicating the calling conventions that are supported. This is important because we use different calling conventions in different places.

One function where we need setjmp() is efi_start_image(). The function is defined as EFIAPI. So we need an implementation supporting the ms_abi calling convention.

Another function where we use setjmp() is do_bootefi_exec() but this function is defined as sysv_abi.

I guess the patch relates to the sysv_abi calling convention:

"System V Application Binary Interface: AMD64 Architecture Processor Supplement (With LP64 and ILP32 Programming Models)"
https://software.intel.com/sites/default/files/article/402129/mpx-linux64-abi.pdf

This document contains the following sentence:

The control bits of the MXCSR register are callee-saved (preserved across calls), while the status bits are caller-saved (not preserved). I cannot see that this is reflected in the patch.

See also https://msdn.microsoft.com/en-us/library/36d3b75w.aspx

Your setjmp implemantion is not usable for the ms_abi that we need in for efi_start_image(). Here you would have to save registers RBX, RBP, RDI, RSI, RSP, R12, R13, R14, and R15.

As reference have a look at this implementation:
https://github.com/freebsd/freebsd/blob/master/lib/libc/amd64/gen/setjmp.S

Best regards

Heinrich

Quoted 35 lines

Signed-off-by Ivan Gorinov <[email protected]>

---
 arch/x86/cpu/x86_64/setjmp.S  | 56 +++++++++++++++++++++++++++++++++++++++++++
 arch/x86/cpu/x86_64/setjmp.c  | 19 ---------------
 arch/x86/include/asm/setjmp.h | 17 +++++++++++++
 3 files changed, 73 insertions(+), 19 deletions(-)
 create mode 100644 arch/x86/cpu/x86_64/setjmp.S
 delete mode 100644 arch/x86/cpu/x86_64/setjmp.c

arch/x86/cpu/x86_64/setjmp.S new file +16 -0

new file mode 100644
index 0000000..e10ee49
@@ -0,0 +1,56 @@
+/*
+ * Based on arch/x86/cpu/i386/setjmp.S by H. Peter Anvin <[email protected]>
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+/*
+ * The jmp_buf is assumed to contain the following, in order:
+ *	<return address>
+ *	%rsp
+ *	%rbp
+ *	%rbx
+ *	%r12
+ *	%r13
+ *	%r14
+ *	%r15

arch/x86/cpu/x86_64/setjmp.S line 24

Quoted 8 lines

arch/x86/cpu/x86_64/setjmp.S new file +8 -0

+ */
+
+.text
+.align 8
+.globl	setjmp
+.type setjmp, @function
+	
+setjmp:

Quoted 93 lines

arch/x86/cpu/x86_64/setjmp.S new file +32 -0

+	pop	%rcx
+	movq	%rcx, (%rdi)	/* Return address */
+	movq	%rsp, 8 (%rdi)	/* Post-return %rsp! */
+	movq	%rbp, 16 (%rdi)
+	movq	%rbx, 24 (%rdi)
+	movq	%r12, 32 (%rdi)
+	movq	%r13, 40 (%rdi)
+	movq	%r14, 48 (%rdi)
+	movq	%r15, 56 (%rdi)
+	xorq	%rax, %rax	/* Return value */
+	jmpq	*%rcx
+
+/* Provide function size if needed */
+.size setjmp, .-setjmp
+
+.align 8
+.globl longjmp
+.type longjmp, @function
+
+longjmp:
+	movq	32 (%rdi), %r12
+	movq	40 (%rdi), %r13
+	movq	48 (%rdi), %r14
+	movq	56 (%rdi), %r15
+	movq	16 (%rdi), %rbp
+	movq	24 (%rdi), %rbx
+	movq	8 (%rdi), %rsp
+	movq	(%rdi), %rcx
+	movq	%rsi, %rdi
+	jmpq	*%rcx
+
+	.size longjmp, .-longjmp

arch/x86/cpu/x86_64/setjmp.c deleted +0 -19

deleted file mode 100644
index 5d4a74a..0000000
@@ -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");
-}

arch/x86/include/asm/setjmp.h +17 -0

index f25975f..49c36c1 100644
@@ -8,6 +8,21 @@
 #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;
+};
+
+#else
+
 struct jmp_buf_data {
 	unsigned int __ebx;
 	unsigned int __esp;

@@ -17,6 +32,8 @@ 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);
 

Quoted 6 lines · Heinrich Schuchardt

Quoted 2 lines · Ivan Gorinov

Add setjmp/longjmp functions for x86_64,
based on existing 32-bit implementation.

Thank you for your patch. This addresses a gap that really should be closed.

Quoted 7 lines

Please, add a line to the commit message indicating the calling conventions that are supported. This is important because we use different calling conventions in different places.

One function where we need setjmp() is efi_start_image(). The function is defined as EFIAPI. So we need an implementation supporting the ms_abi calling convention.

I don't quite follow. The calling convention is declared in the C header (omitted means sysv, EFIAPI means ms). The compiler will adapt the call to the respective convention automatically. So if you call a sysv function from an EFIAPI function, gcc will push all registers that are potentially getting clobbered on the stack.

So IIUC we really only need the sysv variant - which this patch implements, right? This also shouldn't need any mentioning, as it's the default throughout the code base, unless the function is annotated with the EFIAPI tag.

Quoted 14 lines

Another function where we use setjmp() is do_bootefi_exec() but this function is defined as sysv_abi.

I guess the patch relates to the sysv_abi calling convention:

"System V Application Binary Interface: AMD64 Architecture Processor Supplement (With LP64 and ILP32 Programming Models)"
https://software.intel.com/sites/default/files/article/402129/mpx-linux64-abi.pdf

This document contains the following sentence:

The control bits of the MXCSR register are callee-saved (preserved across calls), while the status bits are caller-saved (not preserved). I cannot see that this is reflected in the patch.

Quoted 48 lines

See also https://msdn.microsoft.com/en-us/library/36d3b75w.aspx

Your setjmp implemantion is not usable for the ms_abi that we need in for efi_start_image(). Here you would have to save registers RBX, RBP, RDI, RSI, RSP, R12, R13, R14, and R15.

As reference have a look at this implementation:
https://github.com/freebsd/freebsd/blob/master/lib/libc/amd64/gen/setjmp.S

Quoted 39 lines

Signed-off-by Ivan Gorinov <[email protected]>

---
 arch/x86/cpu/x86_64/setjmp.S  | 56 +++++++++++++++++++++++++++++++++++++++++++
 arch/x86/cpu/x86_64/setjmp.c  | 19 ---------------
 arch/x86/include/asm/setjmp.h | 17 +++++++++++++
 3 files changed, 73 insertions(+), 19 deletions(-)
 create mode 100644 arch/x86/cpu/x86_64/setjmp.S
 delete mode 100644 arch/x86/cpu/x86_64/setjmp.c

arch/x86/cpu/x86_64/setjmp.S new file +20 -0

new file mode 100644
index 0000000..e10ee49
@@ -0,0 +1,56 @@
+/*
+ * Based on arch/x86/cpu/i386/setjmp.S by H. Peter Anvin <[email protected]>
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+/*
+ * The jmp_buf is assumed to contain the following, in order:
+ *	<return address>
+ *	%rsp
+ *	%rbp
+ *	%rbx
+ *	%r12
+ *	%r13
+ *	%r14
+ *	%r15
+ */
+
+.text
+.align 8

Quoted 4 lines

arch/x86/cpu/x86_64/setjmp.S line 24

Quoted 4 lines

arch/x86/cpu/x86_64/setjmp.S new file +4 -0

+.globl	setjmp
+.type setjmp, @function
+	
+setjmp:

We have macros for asm provided functions (see arch/arm/lib/setjmp.S) to ensure that linker based section elimination works. Please make sure you use those.

Quoted 94 lines

Quoted 93 lines

arch/x86/cpu/x86_64/setjmp.S new file +32 -0

+	pop	%rcx
+	movq	%rcx, (%rdi)	/* Return address */
+	movq	%rsp, 8 (%rdi)	/* Post-return %rsp! */
+	movq	%rbp, 16 (%rdi)
+	movq	%rbx, 24 (%rdi)
+	movq	%r12, 32 (%rdi)
+	movq	%r13, 40 (%rdi)
+	movq	%r14, 48 (%rdi)
+	movq	%r15, 56 (%rdi)
+	xorq	%rax, %rax	/* Return value */
+	jmpq	*%rcx
+
+/* Provide function size if needed */
+.size setjmp, .-setjmp
+
+.align 8
+.globl longjmp
+.type longjmp, @function
+
+longjmp:
+	movq	32 (%rdi), %r12
+	movq	40 (%rdi), %r13
+	movq	48 (%rdi), %r14
+	movq	56 (%rdi), %r15
+	movq	16 (%rdi), %rbp
+	movq	24 (%rdi), %rbx
+	movq	8 (%rdi), %rsp
+	movq	(%rdi), %rcx
+	movq	%rsi, %rdi
+	jmpq	*%rcx
+
+	.size longjmp, .-longjmp

arch/x86/cpu/x86_64/setjmp.c deleted +0 -19

deleted file mode 100644
index 5d4a74a..0000000
@@ -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");
-}

arch/x86/include/asm/setjmp.h +17 -0

index f25975f..49c36c1 100644
@@ -8,6 +8,21 @@
 #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;
+};
+
+#else
+
 struct jmp_buf_data {
 	unsigned int __ebx;
 	unsigned int __esp;

@@ -17,6 +32,8 @@ 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);
 

Quoted 15 lines · Alexander Graf

Quoted 6 lines · Heinrich Schuchardt

Quoted 2 lines · Ivan Gorinov

Add setjmp/longjmp functions for x86_64,
based on existing 32-bit implementation.

Thank you for your patch. This addresses a gap that really should be closed.

Quoted 7 lines

Please, add a line to the commit message indicating the calling conventions that are supported. This is important because we use different calling conventions in different places.

One function where we need setjmp() is efi_start_image(). The function is defined as EFIAPI. So we need an implementation supporting the ms_abi calling convention.

Quoted 5 lines

I don't quite follow. The calling convention is declared in the C header (omitted means sysv, EFIAPI means ms). The compiler will adapt the call to the respective convention automatically. So if you call a sysv function from an EFIAPI function, gcc will push all registers that are potentially getting clobbered on the stack.

I can confirm that gcc does save %rsi and %rdi in EFIAPI functions before using those two registers for setjmp() parameters. The other callee-saved registers in ms_abi are also callee-saved in sysv and correctly handled by the proposed implementation.

static efi_status_t EFIAPI efi_start_image(efi_handle_t image_handle,

					   unsigned long *exit_data_size,
					   s16 **exit_data)
{
    5f03ce56:	57                   	push   %rdi
    5f03ce57:	56                   	push   %rsi

    ...

	/* call the image! */
	if (setjmp(&info->exit_jmp)) {
    5f03cecd:	48 8b 84 24 f0 00 00 	mov    0xf0(%rsp),%rax
    5f03ced4:	00 
    5f03ced5:	48 8d 78 78          	lea    0x78(%rax),%rdi
    5f03ced9:	e8 82 32 fc ff       	callq  5f000160 <setjmp>
    5f03cede:	85 c0                	test   %eax,%eax
    5f03cee0:	74 1b                	je     5f03cefd <efi_start_image+0xa7>

    ...

Quoted 19 lines

So IIUC we really only need the sysv variant - which this patch implements, right? This also shouldn't need any mentioning, as it's the default throughout the code base, unless the function is annotated with the EFIAPI tag.

Quoted 14 lines

Another function where we use setjmp() is do_bootefi_exec() but this function is defined as sysv_abi.

I guess the patch relates to the sysv_abi calling convention:

"System V Application Binary Interface: AMD64 Architecture Processor Supplement (With LP64 and ILP32 Programming Models)"
https://software.intel.com/sites/default/files/article/402129/mpx-linux64-abi.pdf

This document contains the following sentence:

The control bits of the MXCSR register are callee-saved (preserved across calls), while the status bits are caller-saved (not preserved). I cannot see that this is reflected in the patch.

Thank you for the link! I will add MXCSR to the callee-saved register set.

Quoted 48 lines

Quoted 48 lines

See also https://msdn.microsoft.com/en-us/library/36d3b75w.aspx

Your setjmp implemantion is not usable for the ms_abi that we need in for efi_start_image(). Here you would have to save registers RBX, RBP, RDI, RSI, RSP, R12, R13, R14, and R15.

As reference have a look at this implementation:
https://github.com/freebsd/freebsd/blob/master/lib/libc/amd64/gen/setjmp.S

Quoted 39 lines

Signed-off-by Ivan Gorinov <[email protected]>

---
 arch/x86/cpu/x86_64/setjmp.S  | 56 +++++++++++++++++++++++++++++++++++++++++++
 arch/x86/cpu/x86_64/setjmp.c  | 19 ---------------
 arch/x86/include/asm/setjmp.h | 17 +++++++++++++
 3 files changed, 73 insertions(+), 19 deletions(-)
 create mode 100644 arch/x86/cpu/x86_64/setjmp.S
 delete mode 100644 arch/x86/cpu/x86_64/setjmp.c

arch/x86/cpu/x86_64/setjmp.S new file +20 -0

new file mode 100644
index 0000000..e10ee49
@@ -0,0 +1,56 @@
+/*
+ * Based on arch/x86/cpu/i386/setjmp.S by H. Peter Anvin <[email protected]>
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+/*
+ * The jmp_buf is assumed to contain the following, in order:
+ *	<return address>
+ *	%rsp
+ *	%rbp
+ *	%rbx
+ *	%r12
+ *	%r13
+ *	%r14
+ *	%r15
+ */
+
+.text
+.align 8

Quoted 8 lines

Quoted 4 lines

arch/x86/cpu/x86_64/setjmp.S line 24

Quoted 4 lines

arch/x86/cpu/x86_64/setjmp.S new file +4 -0

+.globl	setjmp
+.type setjmp, @function
+	
+setjmp:

We have macros for asm provided functions (see arch/arm/lib/setjmp.S) to ensure that linker based section elimination works. Please make sure you use those.

OK. Shall I also add .pushsection/.popsection?
Can't find any example in arch/x86/