mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-07-16 13:19:56 -04:00
Code Issues Packages Projects Releases Wiki Activity

rseq: Add fields and constants for time slice extension

Browse Source 
Aside of a Kconfig knob add the following items:

   - Two flag bits for the rseq user space ABI, which allow user space to
     query the availability and enablement without a syscall.

   - A new member to the user space ABI struct rseq, which is going to be
     used to communicate request and grant between kernel and user space.

   - A rseq state struct to hold the kernel state of this

   - Documentation of the new mechanism

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251215155708.669472597@linutronix.de
This commit is contained in:
Thomas Gleixner
2025-12-15 17:52:04 +01:00
committed by Peter Zijlstra
parent 4fe82cf302
commit d7a5da7a0f
6 changed files with 220 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
include/uapi/linux/rseq.h
View File

@@ -23,9 +23,15 @@ enum rseq_flags {
};
enum rseq_cs_flags_bit {
/* Historical and unsupported bits */
RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0,
RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1,
RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2,
/* (3) Intentional gap to put new bits into a separate byte */
/* User read only feature flags */
RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE_BIT = 4,
RSEQ_CS_FLAG_SLICE_EXT_ENABLED_BIT = 5,
};
enum rseq_cs_flags {
@@ -35,6 +41,11 @@ enum rseq_cs_flags {
(1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE =
(1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),
RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE =
(1U << RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE_BIT),
RSEQ_CS_FLAG_SLICE_EXT_ENABLED =
(1U << RSEQ_CS_FLAG_SLICE_EXT_ENABLED_BIT),
};
/*
@@ -53,6 +64,27 @@ struct rseq_cs {
__u64 abort_ip;
} __attribute__((aligned(4 * sizeof(__u64))));
/**
* rseq_slice_ctrl - Time slice extension control structure
* @all: Compound value
* @request: Request for a time slice extension
* @granted: Granted time slice extension
*
* @request is set by user space and can be cleared by user space or kernel
* space. @granted is set and cleared by the kernel and must only be read
* by user space.
*/
struct rseq_slice_ctrl {
union {
__u32 all;
struct {
__u8 request;
__u8 granted;
__u16 __reserved;
};
};
};
/*
* struct rseq is aligned on 4 * 8 bytes to ensure it is always
* contained within a single cache-line.
@@ -141,6 +173,12 @@ struct rseq {
*/
__u32 mm_cid;
/*
* Time slice extension control structure. CPU local updates from
* kernel and user space.
*/
struct rseq_slice_ctrl slice_ctrl;
/*
* Flexible array member at end of structure, after last feature field.
*/