diff mbox series

[tip:,sched/core] rseq: Introduce feature size and alignment ELF auxiliary vector entries

Message ID 167214323264.4906.3609141535442160200.tip-bot2@tip-bot2
State New
Headers
Series [tip:,sched/core] rseq: Introduce feature size and alignment ELF auxiliary vector entries |

Commit Message

tip-bot2 for Thomas Gleixner Dec. 27, 2022, 12:13 p.m. UTC 
  The following commit has been merged into the sched/core branch of tip:

Commit-ID:     317c8194e6aeb8b3b573ad139fc2a0635856498e
Gitweb:        https://git.kernel.org/tip/317c8194e6aeb8b3b573ad139fc2a0635856498e
Author:        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
AuthorDate:    Tue, 22 Nov 2022 15:39:04 -05:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 27 Dec 2022 12:52:10 +01:00

rseq: Introduce feature size and alignment ELF auxiliary vector entries

Export the rseq feature size supported by the kernel as well as the
required allocation alignment for the rseq per-thread area to user-space
through ELF auxiliary vector entries.

This is part of the extensible rseq ABI.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221122203932.231377-3-mathieu.desnoyers@efficios.com
---
 fs/binfmt_elf.c             | 5 +++++
 include/uapi/linux/auxvec.h | 2 ++
 include/uapi/linux/rseq.h   | 5 +++++
 3 files changed, 12 insertions(+)
diff mbox series

Patch

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index de63572..0ba86f0 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -46,6 +46,7 @@ 
 #include <linux/cred.h>
 #include <linux/dax.h>
 #include <linux/uaccess.h>
+#include <linux/rseq.h>
 #include <asm/param.h>
 #include <asm/page.h>
 
@@ -288,6 +289,10 @@  create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec,
 	if (bprm->have_execfd) {
 		NEW_AUX_ENT(AT_EXECFD, bprm->execfd);
 	}
+#ifdef CONFIG_RSEQ
+	NEW_AUX_ENT(AT_RSEQ_FEATURE_SIZE, offsetof(struct rseq, end));
+	NEW_AUX_ENT(AT_RSEQ_ALIGN, __alignof__(struct rseq));
+#endif
 #undef NEW_AUX_ENT
 	/* AT_NULL is zero; clear the rest too */
 	memset(elf_info, 0, (char *)mm->saved_auxv +
diff --git a/include/uapi/linux/auxvec.h b/include/uapi/linux/auxvec.h
index c7e502b..6991c4b 100644
--- a/include/uapi/linux/auxvec.h
+++ b/include/uapi/linux/auxvec.h
@@ -30,6 +30,8 @@ 
 				 * differ from AT_PLATFORM. */
 #define AT_RANDOM 25	/* address of 16 random bytes */
 #define AT_HWCAP2 26	/* extension of AT_HWCAP */
+#define AT_RSEQ_FEATURE_SIZE	27	/* rseq supported feature size */
+#define AT_RSEQ_ALIGN		28	/* rseq allocation alignment */
 
 #define AT_EXECFN  31	/* filename of program */
 
diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h
index 77ee207..05d3c4c 100644
--- a/include/uapi/linux/rseq.h
+++ b/include/uapi/linux/rseq.h
@@ -130,6 +130,11 @@  struct rseq {
 	 *     this thread.
 	 */
 	__u32 flags;
+
+	/*
+	 * Flexible array member at end of structure, after last feature field.
+	 */
+	char end[];
 } __attribute__((aligned(4 * sizeof(__u64))));
 
 #endif /* _UAPI_LINUX_RSEQ_H */