git: 3a56cfedbc70 - main - fasttrap: Avoid creating WX mappings

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=3a56cfedbc701f8026d38c0d808c614c9f0572ae

commit 3a56cfedbc701f8026d38c0d808c614c9f0572ae
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2022-03-01 16:53:42 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2022-03-01 17:40:35 +0000

    fasttrap: Avoid creating WX mappings
    
    fasttrap instruments certain instructions by overwriting them and
    copying the original instruction to some per-thread scratch space which
    is executed after the probe fires.  This trampoline jumps back to the
    tracepoint after executing the original instruction.
    
    The created mapping has both write and execute permissions, and so this
    mechanism doesn't work when allow_wx is disabled.  Work around the
    restriction by using proc_rwmem() to write to the trampoline.
    
    Reviewed by:    vangyzen
    Tested by:      Amit <akamit91@hotmail.com>
    MFC after:      2 weeks
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D34304
---
 sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c    | 5 +++--
 sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c b/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c
index d96d3f44182e..04ef3ecc3e8d 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c
@@ -336,8 +336,9 @@ fasttrap_scraddr(struct thread *td, fasttrap_proc_t *fprc)
 		 */
 		addr = 0;
 		error = vm_map_find(&p->p_vmspace->vm_map, NULL, 0, &addr,
-		    FASTTRAP_SCRBLOCK_SIZE, 0, VMFS_ANY_SPACE, VM_PROT_ALL,
-		    VM_PROT_ALL, 0);
+		    FASTTRAP_SCRBLOCK_SIZE, 0, VMFS_ANY_SPACE,
+		    VM_PROT_READ | VM_PROT_EXECUTE,
+		    VM_PROT_READ | VM_PROT_EXECUTE, MAP_COPY_ON_WRITE);
 		if (error != KERN_SUCCESS)
 			goto done;
 
diff --git a/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c b/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c
index f92070d8088d..c40b4b94e38d 100644
--- a/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c
+++ b/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c
@@ -1666,7 +1666,7 @@ fasttrap_pid_probe(struct trapframe *tf)
 
 		ASSERT(i <= sizeof (scratch));
 
-		if (fasttrap_copyout(scratch, (char *)addr, i)) {
+		if (uwrite(curproc, scratch, i, addr) != 0) {
 			fasttrap_sigtrap(p, curthread, pc);
 			new_pc = pc;
 			break;