The branch main has been updated by dchagin:
URL:
https://cgit.FreeBSD.org/src/commit/?id=cf8d74e3fe63da7359d6ca7e0b4b57c5684c2845
commit cf8d74e3fe63da7359d6ca7e0b4b57c5684c2845
Author: Dmitry Chagin <dcha...@freebsd.org>
AuthorDate: 2021-07-20 11:39:20 +0000
Commit: Dmitry Chagin <dcha...@freebsd.org>
CommitDate: 2021-07-20 11:39:20 +0000
linux(4): Allow musl brand to use FUTEX_REQUEUE op.
Initial patch from submitter was adapted by me to prevent unconditional
FUTEX_REQUEUE use.
PR: 255947
Submitted by: Philippe Michaud-Boudreault
Differential Revision: https://reviews.freebsd.org/D30332
---
sys/amd64/linux/linux_sysvec.c | 3 ++-
sys/amd64/linux32/linux32_sysvec.c | 3 ++-
sys/compat/linux/linux.h | 5 ++++
sys/compat/linux/linux_futex.c | 49 +++++++++++++++++++++++++-------------
sys/i386/linux/linux_sysvec.c | 3 ++-
5 files changed, 43 insertions(+), 20 deletions(-)
diff --git a/sys/amd64/linux/linux_sysvec.c b/sys/amd64/linux/linux_sysvec.c
index dc9a77093bcd..fede294ce706 100644
--- a/sys/amd64/linux/linux_sysvec.c
+++ b/sys/amd64/linux/linux_sysvec.c
@@ -991,7 +991,8 @@ static Elf64_Brandinfo linux_muslbrand = {
.sysvec = &elf_linux_sysvec,
.interp_newpath = NULL,
.brand_note = &linux64_brandnote,
- .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
+ .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE |
+ LINUX_BI_FUTEX_REQUEUE
};
Elf64_Brandinfo *linux_brandlist[] = {
diff --git a/sys/amd64/linux32/linux32_sysvec.c
b/sys/amd64/linux32/linux32_sysvec.c
index 5176029605bf..901c79fcdda8 100644
--- a/sys/amd64/linux32/linux32_sysvec.c
+++ b/sys/amd64/linux32/linux32_sysvec.c
@@ -1154,7 +1154,8 @@ static Elf32_Brandinfo linux_muslbrand = {
.sysvec = &elf_linux_sysvec,
.interp_newpath = NULL,
.brand_note = &linux32_brandnote,
- .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
+ .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE |
+ LINUX_BI_FUTEX_REQUEUE
};
Elf32_Brandinfo *linux_brandlist[] = {
diff --git a/sys/compat/linux/linux.h b/sys/compat/linux/linux.h
index 15830b5b387e..730aece66a6a 100644
--- a/sys/compat/linux/linux.h
+++ b/sys/compat/linux/linux.h
@@ -30,6 +30,11 @@
#include <sys/queue.h>
+/*
+ * Private Brandinfo flags
+ */
+#define LINUX_BI_FUTEX_REQUEUE 0x01000000
+
/*
* poll()
*/
diff --git a/sys/compat/linux/linux_futex.c b/sys/compat/linux/linux_futex.c
index 1ba11ed3fc57..2ee18c26cf24 100644
--- a/sys/compat/linux/linux_futex.c
+++ b/sys/compat/linux/linux_futex.c
@@ -46,6 +46,7 @@ __KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24
19:01:49 manu Exp $")
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/imgact.h>
+#include <sys/imgact_elf.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
@@ -234,6 +235,7 @@ struct linux_futex_args {
struct timespec *ts;
uint32_t *uaddr2;
uint32_t val3;
+ bool val3_compare;
struct timespec kts;
};
@@ -648,6 +650,7 @@ static int
linux_futex(struct thread *td, struct linux_futex_args *args)
{
struct linux_pemuldata *pem;
+ struct proc *p;
if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
args->flags = 0;
@@ -695,6 +698,33 @@ linux_futex(struct thread *td, struct linux_futex_args
*args)
return (linux_futex_wake(td, args));
+ case LINUX_FUTEX_REQUEUE:
+ /*
+ * Glibc does not use this operation since version 2.3.3,
+ * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
+ * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
+ * FUTEX_REQUEUE returned EINVAL.
+ */
+ pem = pem_find(td->td_proc);
+ if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
+ linux_msg(td, "unsupported FUTEX_REQUEUE");
+ pem->flags |= LINUX_XDEPR_REQUEUEOP;
+ LIN_SDT_PROBE0(futex, linux_futex,
+ deprecated_requeue);
+ }
+
+ /*
+ * The above is true, however musl libc does make use of the
+ * futex requeue operation, allow operation for brands which
+ * set LINUX_BI_FUTEX_REQUEUE bit of Brandinfo flags.
+ */
+ p = td->td_proc;
+ Elf_Brandinfo *bi = p->p_elf_brandinfo;
+ if (bi == NULL || ((bi->flags & LINUX_BI_FUTEX_REQUEUE)) == 0)
+ return (EINVAL);
+ args->val3_compare = false;
+ /* FALLTHROUGH */
+
case LINUX_FUTEX_CMP_REQUEUE:
LIN_SDT_PROBE5(futex, linux_futex, debug_cmp_requeue,
args->uaddr, args->val, args->val3, args->uaddr2,
@@ -749,22 +779,6 @@ linux_futex(struct thread *td, struct linux_futex_args
*args)
}
return (ENOSYS);
- case LINUX_FUTEX_REQUEUE:
- /*
- * Glibc does not use this operation since version 2.3.3,
- * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
- * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
- * FUTEX_REQUEUE returned EINVAL.
- */
- pem = pem_find(td->td_proc);
- if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
- linux_msg(td, "unsupported FUTEX_REQUEUE");
- pem->flags |= LINUX_XDEPR_REQUEUEOP;
- LIN_SDT_PROBE0(futex, linux_futex,
- deprecated_requeue);
- }
- return (EINVAL);
-
case LINUX_FUTEX_WAIT_REQUEUE_PI:
/* not yet implemented */
pem = pem_find(td->td_proc);
@@ -921,7 +935,7 @@ retry:
error);
return (error);
}
- if (val != args->val3) {
+ if (args->val3_compare == true && val != args->val3) {
LIN_SDT_PROBE2(futex, linux_futex,
debug_cmp_requeue_value_neq, args->val, val);
LINUX_CTR2(sys_futex, "CMP_REQUEUE val 0x%x != uval 0x%x",
@@ -1016,6 +1030,7 @@ linux_sys_futex(struct thread *td, struct
linux_sys_futex_args *args)
.ts = NULL,
.uaddr2 = args->uaddr2,
.val3 = args->val3,
+ .val3_compare = true,
};
struct l_timespec lts;
int error;
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index f3101db96d41..1fcc1b6eb5a0 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -1099,7 +1099,8 @@ static Elf32_Brandinfo linux_muslbrand = {
.sysvec = &elf_linux_sysvec,
.interp_newpath = NULL,
.brand_note = &linux_brandnote,
- .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
+ .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE |
+ LINUX_BI_FUTEX_REQUEUE
};
Elf32_Brandinfo *linux_brandlist[] = {
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