netbsd-sigtramp-unwind.patch

Index: arch/x86_64/sys/__sigtramp2.S
===================================================================
RCS file: /cvsroot/src/lib/libc/arch/x86_64/sys/__sigtramp2.S,v
retrieving revision 1.7
diff -u -r1.7 __sigtramp2.S
--- arch/x86_64/sys/__sigtramp2.S       2 Dec 2019 01:38:54 -0000       1.7
+++ arch/x86_64/sys/__sigtramp2.S       12 Oct 2020 04:22:11 -0000
@@ -36,14 +36,40 @@
  */
 
 #include "SYS.h"
+#include "assym.h"
 
 /*
  * The x86-64 signal trampoline is invoked only to return from
  * the signal; the kernel calls the signal handler directly.
+ *
+ * The unwind entry includes the one byte prior to the trampoline
+ * because the unwinder will look up (return PC - 1) while unwinding.
+ * Normally (return PC - 1) computes an address inside the call
+ * instruction that created the child frame, but here there is no call
+ * instruction so we have to manually add padding.
  */
+       .cfi_startproc simple
+       .cfi_signal_frame
+       .cfi_def_cfa r15, 0
+       .cfi_offset rax, _OFFSETOF_UC_GREGS_RAX
+       .cfi_offset rdx, _OFFSETOF_UC_GREGS_RDX
+       .cfi_offset rcx, _OFFSETOF_UC_GREGS_RCX
+       .cfi_offset rbx, _OFFSETOF_UC_GREGS_RBX
+       .cfi_offset rsi, _OFFSETOF_UC_GREGS_RSI
+       .cfi_offset rdi, _OFFSETOF_UC_GREGS_RDI
+       .cfi_offset rbp, _OFFSETOF_UC_GREGS_RBP
+       /* The unwinder will use the CFA to restore RSP. */
+       .cfi_offset r8,  _OFFSETOF_UC_GREGS_R8
+       .cfi_offset r9,  _OFFSETOF_UC_GREGS_R9
+       .cfi_offset r10, _OFFSETOF_UC_GREGS_R10
+       .cfi_offset r11, _OFFSETOF_UC_GREGS_R11
+       .cfi_offset r12, _OFFSETOF_UC_GREGS_R12
+       .cfi_offset r13, _OFFSETOF_UC_GREGS_R13
+       .cfi_offset r14, _OFFSETOF_UC_GREGS_R14
+       .cfi_offset r15, _OFFSETOF_UC_GREGS_R15
+       .cfi_offset rip, _OFFSETOF_UC_GREGS_RIP
+       nop
 NENTRY(__sigtramp_siginfo_2)
-       .cfi_startproc
-       .cfi_def_cfa rsp, 8
        movq    %r15,%rdi
        movq    $SYS_setcontext, %rax
        syscall
Index: arch/x86_64/genassym.cf
===================================================================
RCS file: arch/x86_64/genassym.cf
diff -N arch/x86_64/genassym.cf
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ arch/x86_64/genassym.cf     12 Oct 2020 04:22:11 -0000
@@ -0,0 +1,19 @@
+include <ucontext.h>
+
+define _OFFSETOF_UC_GREGS_RAX offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RAX])
+define _OFFSETOF_UC_GREGS_RDX offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RDX])
+define _OFFSETOF_UC_GREGS_RCX offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RCX])
+define _OFFSETOF_UC_GREGS_RBX offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RBX])
+define _OFFSETOF_UC_GREGS_RSI offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RSI])
+define _OFFSETOF_UC_GREGS_RDI offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RDI])
+define _OFFSETOF_UC_GREGS_RBP offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RBP])
+define _OFFSETOF_UC_GREGS_RSP offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RSP])
+define _OFFSETOF_UC_GREGS_R8  offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R8])
+define _OFFSETOF_UC_GREGS_R9  offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R9])
+define _OFFSETOF_UC_GREGS_R10 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R10])
+define _OFFSETOF_UC_GREGS_R11 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R11])
+define _OFFSETOF_UC_GREGS_R12 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R12])
+define _OFFSETOF_UC_GREGS_R13 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R13])
+define _OFFSETOF_UC_GREGS_R14 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R14])
+define _OFFSETOF_UC_GREGS_R15 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R15])
+define _OFFSETOF_UC_GREGS_RIP offsetof(ucontext_t, uc_mcontext.__gregs[_REG_RIP])