/* SPDX-License-Identifier: MIT */
/* SPDX-FileCopyrightText: 2018 MIPS Tech LLC */
-/* SPDX-FileCopyrightText: 2016-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> */
+/* SPDX-FileCopyrightText: 2016-2024 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> */
/*
* Author: Paul Burton <paul.burton@mips.com>
*/
+/*
+ * RSEQ_ASM_*() macro helpers are internal to the librseq headers. Those
+ * are not part of the public API.
+ */
+
/*
* RSEQ_SIG uses the break instruction. The instruction pattern is:
*
/* Unknown MIPS architecture. */
#endif
+/*
+ * Refer to the Linux kernel memory model (LKMM) for documentation of
+ * the memory barriers.
+ */
+
+/* CPU memory barrier. */
#define rseq_smp_mb() __asm__ __volatile__ ("sync" ::: "memory")
+/* CPU read memory barrier */
#define rseq_smp_rmb() rseq_smp_mb()
+/* CPU write memory barrier */
#define rseq_smp_wmb() rseq_smp_mb()
+/* Acquire: One-way permeable barrier. */
#define rseq_smp_load_acquire(p) \
__extension__ ({ \
rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p)); \
____p1; \
})
+/* Acquire barrier after control dependency. */
#define rseq_smp_acquire__after_ctrl_dep() rseq_smp_rmb()
+/* Release: One-way permeable barrier. */
#define rseq_smp_store_release(p, v) \
do { \
rseq_smp_mb(); \
RSEQ_WRITE_ONCE(*(p), v); \
} while (0)
+/*
+ * Helper macros to define and access a variable of pointer type stored
+ * in a 64-bit integer. Only used internally in rseq headers.
+ */
#if _MIPS_SZLONG == 64
# define RSEQ_ASM_LONG ".dword"
# define RSEQ_ASM_LONG_LA "dla"
# error unsupported _MIPS_SZLONG
#endif
+/* Only used in RSEQ_ASM_DEFINE_TABLE. */
#define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, start_ip, \
post_commit_offset, abort_ip) \
".pushsection __rseq_cs, \"aw\"\n\t" \
RSEQ_ASM_LONG " " RSEQ_ASM_U32_U64_PAD(__rseq_str(label) "b") "\n\t" \
".popsection\n\t"
+/*
+ * Define an rseq critical section structure of version 0 with no flags.
+ *
+ * @label:
+ * Local label for the beginning of the critical section descriptor
+ * structure.
+ * @start_ip:
+ * Pointer to the first instruction of the sequence of consecutive assembly
+ * instructions.
+ * @post_commit_ip:
+ * Pointer to the instruction after the last instruction of the sequence of
+ * consecutive assembly instructions.
+ * @abort_ip:
+ * Pointer to the instruction where to move the execution flow in case of
+ * abort of the sequence of consecutive assembly instructions.
+ */
#define RSEQ_ASM_DEFINE_TABLE(label, start_ip, post_commit_ip, abort_ip) \
__RSEQ_ASM_DEFINE_TABLE(label, 0x0, 0x0, start_ip, \
(post_commit_ip - start_ip), abort_ip)
/*
+ * Define the @exit_ip pointer as an exit point for the sequence of consecutive
+ * assembly instructions at @start_ip.
+ *
+ * @start_ip:
+ * Pointer to the first instruction of the sequence of consecutive assembly
+ * instructions.
+ * @exit_ip:
+ * Pointer to an exit point instruction.
+ *
* Exit points of a rseq critical section consist of all instructions outside
* of the critical section where a critical section can either branch to or
* reach through the normal course of its execution. The abort IP and the
RSEQ_ASM_LONG " " RSEQ_ASM_U32_U64_PAD(__rseq_str(exit_ip)) "\n\t" \
".popsection\n\t"
-#define RSEQ_ASM_STORE_RSEQ_CS(label, cs_label, rseq_cs) \
- RSEQ_INJECT_ASM(1) \
- RSEQ_ASM_LONG_LA " $4, " __rseq_str(cs_label) "\n\t" \
- RSEQ_ASM_LONG_S " $4, %[" __rseq_str(rseq_cs) "]\n\t" \
- __rseq_str(label) ":\n\t"
-
-#define RSEQ_ASM_CBNE_CPU_ID(cpu_id, current_cpu_id, label) \
- RSEQ_INJECT_ASM(2) \
- "lw $4, %[" __rseq_str(current_cpu_id) "]\n\t" \
- "bne $4, %[" __rseq_str(cpu_id) "], " __rseq_str(label) "\n\t"
-
+/* Only used in RSEQ_ASM_DEFINE_ABORT. */
#define __RSEQ_ASM_DEFINE_ABORT(table_label, label, teardown, \
abort_label, version, flags, \
start_ip, post_commit_offset, abort_ip) \
teardown \
"b %l[" __rseq_str(abort_label) "]\n\t"
+/*
+ * Define a critical section abort handler.
+ *
+ * @table_label:
+ * Local label to the critical section descriptor copy placed near
+ * the program counter. This is done for performance reasons because
+ * computing this address is faster than accessing the program data.
+ * @label:
+ * Local label to the abort handler.
+ * @teardown:
+ * Sequence of instructions to run on abort.
+ * @abort_label:
+ * C label to jump to at the end of the sequence.
+ *
+ * The purpose of @start_ip, @post_commit_ip, and @abort_ip are
+ * documented in RSEQ_ASM_DEFINE_TABLE.
+ */
#define RSEQ_ASM_DEFINE_ABORT(table_label, label, teardown, abort_label, \
start_ip, post_commit_ip, abort_ip) \
__RSEQ_ASM_DEFINE_ABORT(table_label, label, teardown, \
abort_label, 0x0, 0x0, start_ip, \
(post_commit_ip - start_ip), abort_ip)
+/*
+ * Define a critical section teardown handler.
+ *
+ * @label:
+ * Local label to the teardown handler.
+ * @teardown:
+ * Sequence of instructions to run on teardown.
+ * @target_label:
+ * C label to jump to at the end of the sequence.
+ */
#define RSEQ_ASM_DEFINE_TEARDOWN(label, teardown, target_label) \
__rseq_str(label) ":\n\t" \
teardown \
"b %l[" __rseq_str(target_label) "]\n\t"
+/*
+ * Store the address of the critical section descriptor structure at
+ * @cs_label into the @rseq_cs pointer and emit the label @label, which
+ * is the beginning of the sequence of consecutive assembly instructions.
+ *
+ * @label:
+ * Local label to the beginning of the sequence of consecutive assembly
+ * instructions.
+ * @cs_label:
+ * Source local label to the critical section descriptor structure.
+ * @rseq_cs:
+ * Destination pointer where to store the address of the critical
+ * section descriptor structure.
+ */
+#define RSEQ_ASM_STORE_RSEQ_CS(label, cs_label, rseq_cs) \
+ RSEQ_INJECT_ASM(1) \
+ RSEQ_ASM_LONG_LA " $4, " __rseq_str(cs_label) "\n\t" \
+ RSEQ_ASM_LONG_S " $4, %[" __rseq_str(rseq_cs) "]\n\t" \
+ __rseq_str(label) ":\n\t"
+
+/* Jump to local label @label when @cpu_id != @current_cpu_id. */
+#define RSEQ_ASM_CBNE_CPU_ID(cpu_id, current_cpu_id, label) \
+ RSEQ_INJECT_ASM(2) \
+ "lw $4, %[" __rseq_str(current_cpu_id) "]\n\t" \
+ "bne $4, %[" __rseq_str(cpu_id) "], " __rseq_str(label) "\n\t"
+
/* Per-cpu-id indexing. */
#define RSEQ_TEMPLATE_INDEX_CPU_ID
projects / librseq.git / commitdiff
