From: David Woodhouse <dwmw@xxxxxxxxxxxx>
The actual serial output function is a no-op for now.
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
arch/x86/kernel/relocate_kernel_64.S | 121 +++++++++++++++++++++++++--
1 file changed, 115 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index b07c55019ce5..c2f73998d1b6 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -379,6 +379,69 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
int3
SYM_CODE_END(swap_pages)
+/*
+ * Generic 'print character' routine (as yet unimplemented)
+ * - %al: Character to be printed (may clobber %rax)
+ * - %rdx: MMIO address or port.
+ */
+SYM_CODE_START_LOCAL_NOALIGN(pr_char)
+ UNWIND_HINT_FUNC
+ ANNOTATE_NOENDBR
+ ANNOTATE_UNRET_SAFE
+ ret
+SYM_CODE_END(pr_char)
+
+/*
+ * Load pr_char function pointer into %rsi and load %rdx with whatever
+ * that function wants to see there (typically port/MMIO address).
+ */
+.macro pr_setup
+ /* No output; pr_char just returns */
+ leaq pr_char(%rip), %rsi
+.endm
+
+/* Print the nybble in %bl, clobber %rax */
+SYM_CODE_START_LOCAL_NOALIGN(pr_nybble)
+ UNWIND_HINT_FUNC
+ movb %bl, %al
+ nop
+ andb $0x0f, %al
+ addb $0x30, %al
+ cmpb $0x3a, %al
+ jb 1f
+ addb $('a' - '0' - 10), %al
+ ANNOTATE_RETPOLINE_SAFE
+1: jmp *%rsi
+SYM_CODE_END(pr_nybble)
+
+SYM_CODE_START_LOCAL_NOALIGN(pr_qword)
+ UNWIND_HINT_FUNC
+ movq $16, %rcx
+1: rolq $4, %rbx
+ call pr_nybble
+ loop 1b
+ movb $'\n', %al
+ ANNOTATE_RETPOLINE_SAFE
+ jmp *%rsi
+SYM_CODE_END(pr_qword)
+
+.macro print_reg a, b, c, d, r
+ movb $\a, %al
+ ANNOTATE_RETPOLINE_SAFE
+ call *%rsi
+ movb $\b, %al
+ ANNOTATE_RETPOLINE_SAFE
+ call *%rsi
+ movb $\c, %al
+ ANNOTATE_RETPOLINE_SAFE
+ call *%rsi
+ movb $\d, %al
+ ANNOTATE_RETPOLINE_SAFE
+ call *%rsi
+ movq \r, %rbx
+ call pr_qword
+.endm
+
SYM_CODE_START_NOALIGN(kexec_debug_exc_vectors)
/* Each of these is 6 bytes. */
.macro vec_err exc
@@ -422,17 +485,63 @@ SYM_CODE_START_LOCAL_NOALIGN(exc_handler)
VALIDATE_UNRET_END
pushq %rax
+ pushq %rbx
+ pushq %rcx
pushq %rdx
- movw $0x3f8, %dx
- movb $'A', %al
- outb %al, %dx
- popq %rdx
- popq %rax
+ pushq %rsi
+
+ /* Stack frame */
+#define EXC_SS 0x58 /* Architectural... */
+#define EXC_RSP 0x50
+#define EXC_EFLAGS 0x48
+#define EXC_CS 0x40
+#define EXC_RIP 0x38
+#define EXC_ERRORCODE 0x30 /* Either architectural or zero pushed by handler */
+#define EXC_EXCEPTION 0x28 /* Pushed by handler entry point */
+#define EXC_RAX 0x20 /* Pushed just above in exc_handler */
+#define EXC_RBX 0x18
+#define EXC_RCX 0x10
+#define EXC_RDX 0x08
+#define EXC_RSI 0x00
+
+ /* Set up %rdx/%rsi for debug output */
+ pr_setup
+
+ /* rip and exception info */
+ print_reg 'E', 'x', 'c', ':', EXC_EXCEPTION(%rsp)
+ print_reg 'E', 'r', 'r', ':', EXC_ERRORCODE(%rsp)
+ print_reg 'r', 'i', 'p', ':', EXC_RIP(%rsp)
+ print_reg 'r', 's', 'p', ':', EXC_RSP(%rsp)
+
+ /* We spilled these to the stack */
+ print_reg 'r', 'a', 'x', ':', EXC_RAX(%rsp)
+ print_reg 'r', 'b', 'x', ':', EXC_RBX(%rsp)
+ print_reg 'r', 'c', 'x', ':', EXC_RCX(%rsp)
+ print_reg 'r', 'd', 'x', ':', EXC_RDX(%rsp)
+ print_reg 'r', 's', 'i', ':', EXC_RSI(%rsp)
+
+ /* Other registers untouched */
+ print_reg 'r', 'd', 'i', ':', %rdi
+ print_reg 'r', '8', ' ', ':', %r8
+ print_reg 'r', '9', ' ', ':', %r9
+ print_reg 'r', '1', '0', ':', %r10
+ print_reg 'r', '1', '1', ':', %r11
+ print_reg 'r', '1', '2', ':', %r12
+ print_reg 'r', '1', '3', ':', %r13
+ print_reg 'r', '1', '4', ':', %r14
+ print_reg 'r', '1', '5', ':', %r15
+ print_reg 'c', 'r', '2', ':', %cr2
/* Only return from int3 */
- cmpq $3, (%rsp)
+ cmpq $3, EXC_EXCEPTION(%rsp)
jne .Ldie
+ popq %rsi
+ popq %rdx
+ popq %rcx
+ popq %rbx
+ popq %rax
+
addq $16, %rsp
iretq
--
2.48.1
