[libc-commits] [libc] [libc] Add ucontext types and headers (PR #191789)
Jeff Bailey via libc-commits
libc-commits at lists.llvm.org
Mon Apr 13 06:42:00 PDT 2026
https://github.com/kaladron updated https://github.com/llvm/llvm-project/pull/191789
>From 2cfdc3644786cac8514e858bc90a91f983b1f8ee Mon Sep 17 00:00:00 2001
From: Jeff Bailey <jbailey at raspberryginger.com>
Date: Mon, 13 Apr 2026 10:39:41 +0100
Subject: [PATCH] [libc] Add ucontext types and headers
Added mcontext_t and ucontext_t types for x86_64 Linux, and the ucontext.h header definition. Used a dispatcher pattern for mcontext_t and ucontext_t to support future architecture ports, mirroring the pattern used in FPUtil.
Definitions are based on the Linux kernel ABI for x86_64.
---
libc/include/CMakeLists.txt | 14 ++++
libc/include/llvm-libc-types/CMakeLists.txt | 25 +++++++
libc/include/llvm-libc-types/mcontext_t.h | 18 +++++
libc/include/llvm-libc-types/ucontext_t.h | 18 +++++
.../llvm-libc-types/x86_64/mcontext_t.h | 75 +++++++++++++++++++
.../llvm-libc-types/x86_64/ucontext_t.h | 26 +++++++
libc/include/ucontext.h.def | 16 ++++
libc/include/ucontext.yaml | 37 +++++++++
8 files changed, 229 insertions(+)
create mode 100644 libc/include/llvm-libc-types/mcontext_t.h
create mode 100644 libc/include/llvm-libc-types/ucontext_t.h
create mode 100644 libc/include/llvm-libc-types/x86_64/mcontext_t.h
create mode 100644 libc/include/llvm-libc-types/x86_64/ucontext_t.h
create mode 100644 libc/include/ucontext.h.def
create mode 100644 libc/include/ucontext.yaml
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
index 41d541f475290..41e3fc200ab71 100644
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -460,6 +460,20 @@ add_header_macro(
.llvm_libc_common_h
)
+if(LIBC_TARGET_ARCHITECTURE STREQUAL "x86_64")
+ add_header_macro(
+ ucontext
+ ../libc/include/ucontext.yaml
+ ucontext.h
+ DEPENDS
+ .llvm_libc_common_h
+ .llvm-libc-types.mcontext_t
+ .llvm-libc-types.ucontext_t
+ .llvm-libc-types.sigset_t
+ .llvm-libc-types.stack_t
+ )
+endif()
+
add_header_macro(
sched
../libc/include/sched.yaml
diff --git a/libc/include/llvm-libc-types/CMakeLists.txt b/libc/include/llvm-libc-types/CMakeLists.txt
index 0d6bc0982b847..e40f6e194ab3a 100644
--- a/libc/include/llvm-libc-types/CMakeLists.txt
+++ b/libc/include/llvm-libc-types/CMakeLists.txt
@@ -126,6 +126,31 @@ add_header(union_sigval HDR union_sigval.h)
add_header(siginfo_t HDR siginfo_t.h DEPENDS .union_sigval .pid_t .uid_t .clock_t)
add_header(sig_atomic_t HDR sig_atomic_t.h)
add_header(sigset_t HDR sigset_t.h DEPENDS libc.include.llvm-libc-macros.signal_macros)
+set(mcontext_deps)
+set(ucontext_deps .sigset_t .stack_t)
+
+if(LIBC_TARGET_ARCHITECTURE STREQUAL "x86_64")
+ file(COPY x86_64 DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
+ add_header(
+ mcontext_t_arch
+ HDR
+ x86_64/mcontext_t.h
+ )
+ add_header(
+ ucontext_t_arch
+ HDR
+ x86_64/ucontext_t.h
+ DEPENDS
+ .mcontext_t_arch
+ .sigset_t
+ .stack_t
+ )
+ list(APPEND mcontext_deps .mcontext_t_arch)
+ list(APPEND ucontext_deps .ucontext_t_arch)
+endif()
+
+add_header(mcontext_t HDR mcontext_t.h DEPENDS ${mcontext_deps})
+add_header(ucontext_t HDR ucontext_t.h DEPENDS .mcontext_t ${ucontext_deps})
add_header(__jmp_buf HDR __jmp_buf.h DEPENDS .sigset_t)
add_header(jmp_buf HDR jmp_buf.h DEPENDS .__jmp_buf)
add_header(sigjmp_buf HDR sigjmp_buf.h DEPENDS .__jmp_buf)
diff --git a/libc/include/llvm-libc-types/mcontext_t.h b/libc/include/llvm-libc-types/mcontext_t.h
new file mode 100644
index 0000000000000..f2226555c2ac8
--- /dev/null
+++ b/libc/include/llvm-libc-types/mcontext_t.h
@@ -0,0 +1,18 @@
+//===-- Definition of type mcontext_t -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_TYPES_MCONTEXT_T_H
+#define LLVM_LIBC_TYPES_MCONTEXT_T_H
+
+#if defined(__x86_64__)
+#include "x86_64/mcontext_t.h"
+#else
+#error "mcontext_t not available for your target architecture."
+#endif
+
+#endif // LLVM_LIBC_TYPES_MCONTEXT_T_H
diff --git a/libc/include/llvm-libc-types/ucontext_t.h b/libc/include/llvm-libc-types/ucontext_t.h
new file mode 100644
index 0000000000000..1c5319bf807fa
--- /dev/null
+++ b/libc/include/llvm-libc-types/ucontext_t.h
@@ -0,0 +1,18 @@
+//===-- Definition of type ucontext_t -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_TYPES_UCONTEXT_T_H
+#define LLVM_LIBC_TYPES_UCONTEXT_T_H
+
+#if defined(__x86_64__)
+#include "x86_64/ucontext_t.h"
+#else
+#error "ucontext_t not available for your target architecture."
+#endif
+
+#endif // LLVM_LIBC_TYPES_UCONTEXT_T_H
diff --git a/libc/include/llvm-libc-types/x86_64/mcontext_t.h b/libc/include/llvm-libc-types/x86_64/mcontext_t.h
new file mode 100644
index 0000000000000..4bf7023a85feb
--- /dev/null
+++ b/libc/include/llvm-libc-types/x86_64/mcontext_t.h
@@ -0,0 +1,75 @@
+//===-- Definition of type mcontext_t -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Note: Definitions in this file are based on the Linux kernel ABI.
+
+#ifndef LLVM_LIBC_TYPES_MCONTEXT_T_H
+#define LLVM_LIBC_TYPES_MCONTEXT_T_H
+
+typedef long long int greg_t;
+typedef greg_t gregset_t[23];
+
+enum {
+ __LIBC_REG_R8 = 0,
+ __LIBC_REG_R9,
+ __LIBC_REG_R10,
+ __LIBC_REG_R11,
+ __LIBC_REG_R12,
+ __LIBC_REG_R13,
+ __LIBC_REG_R14,
+ __LIBC_REG_R15,
+ __LIBC_REG_RDI,
+ __LIBC_REG_RSI,
+ __LIBC_REG_RBP,
+ __LIBC_REG_RBX,
+ __LIBC_REG_RDX,
+ __LIBC_REG_RAX,
+ __LIBC_REG_RCX,
+ __LIBC_REG_RSP,
+ __LIBC_REG_RIP,
+ __LIBC_REG_EFL,
+ __LIBC_REG_CSGSFS,
+ __LIBC_REG_ERR,
+ __LIBC_REG_TRAPNO,
+ __LIBC_REG_OLDMASK,
+ __LIBC_REG_CR2
+};
+
+struct _libc_fpxreg {
+ unsigned short significand[4];
+ unsigned short exponent;
+ unsigned short padding[3];
+};
+
+struct _libc_xmmreg {
+ unsigned int element[4];
+};
+
+struct _libc_fpstate {
+ unsigned short cwd;
+ unsigned short swd;
+ unsigned short ftw;
+ unsigned short fop;
+ unsigned long long rip;
+ unsigned long long rdp;
+ unsigned int mxcsr;
+ unsigned int mxcr_mask;
+ struct _libc_fpxreg _st[8];
+ struct _libc_xmmreg _xmm[16];
+ unsigned int padding[24];
+};
+
+typedef struct _libc_fpstate *fpregset_t;
+
+typedef struct {
+ gregset_t gregs;
+ fpregset_t fpregs;
+ unsigned long long __reserved1[8];
+} mcontext_t;
+
+#endif // LLVM_LIBC_TYPES_MCONTEXT_T_H
diff --git a/libc/include/llvm-libc-types/x86_64/ucontext_t.h b/libc/include/llvm-libc-types/x86_64/ucontext_t.h
new file mode 100644
index 0000000000000..d98ddf7819bb8
--- /dev/null
+++ b/libc/include/llvm-libc-types/x86_64/ucontext_t.h
@@ -0,0 +1,26 @@
+//===-- Definition of type ucontext_t -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Note: Definitions in this file are based on the Linux kernel ABI.
+
+#ifndef LLVM_LIBC_TYPES_UCONTEXT_T_H
+#define LLVM_LIBC_TYPES_UCONTEXT_T_H
+
+#include "../sigset_t.h"
+#include "../stack_t.h"
+#include "mcontext_t.h"
+
+typedef struct alignas(16) ucontext_t {
+ unsigned long uc_flags;
+ struct ucontext_t *uc_link;
+ stack_t uc_stack;
+ mcontext_t uc_mcontext;
+ sigset_t uc_sigmask;
+} ucontext_t;
+
+#endif // LLVM_LIBC_TYPES_UCONTEXT_T_H
diff --git a/libc/include/ucontext.h.def b/libc/include/ucontext.h.def
new file mode 100644
index 0000000000000..0750d99a4a0c5
--- /dev/null
+++ b/libc/include/ucontext.h.def
@@ -0,0 +1,16 @@
+//===-- POSIX header ucontext.h --------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_UCONTEXT_H
+#define LLVM_LIBC_UCONTEXT_H
+
+#include "__llvm-libc-common.h"
+
+%%public_api()
+
+#endif // LLVM_LIBC_UCONTEXT_H
diff --git a/libc/include/ucontext.yaml b/libc/include/ucontext.yaml
new file mode 100644
index 0000000000000..05ae5e9d38602
--- /dev/null
+++ b/libc/include/ucontext.yaml
@@ -0,0 +1,37 @@
+header: ucontext.h
+standards:
+ - posix
+types:
+ - type_name: mcontext_t
+ - type_name: ucontext_t
+ - type_name: sigset_t
+ - type_name: stack_t
+functions:
+ - name: getcontext
+ standards:
+ - posix
+ return_type: int
+ arguments:
+ - type: ucontext_t *
+ - name: setcontext
+ standards:
+ - posix
+ return_type: int
+ arguments:
+ - type: const ucontext_t *
+ - name: makecontext
+ standards:
+ - posix
+ return_type: void
+ arguments:
+ - type: ucontext_t *
+ - type: void(*)(void)
+ - type: int
+ - type: ...
+ - name: swapcontext
+ standards:
+ - posix
+ return_type: int
+ arguments:
+ - type: ucontext_t *__restrict
+ - type: const ucontext_t *__restrict
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