From: Stefan Liebler <stli@linux.ibm.com>
Date: Fri, 15 Dec 2023 08:26:40 +0000 (+0100)
Subject: s390: Set psw addr field in getcontext and friends.
X-Git-Tag: glibc-2.39~197
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=664f565f9caa26bb128bad7d7050cf0f0b9c6322;p=thirdparty%2Fglibc.git

s390: Set psw addr field in getcontext and friends.

So far if the ucontext structure was obtained by getcontext and co,
the return address was stored in general purpose register 14 as
it is defined as return address in the ABI.

In contrast, the context passed to a signal handler contains the address
in psw.addr field.

If somebody e.g. wants to dump the address of the context, the origin
needs to be known.

Now this patch adjusts getcontext and friends and stores the return address
also in psw.addr field.

Note that setcontext isn't adjusted and it is not supported to pass a
ucontext structure from signal-handler to setcontext.  We are not able to
restore all registers and branching to psw.addr without clobbering one
register.
---

diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/getcontext.S b/sysdeps/unix/sysv/linux/s390/s390-32/getcontext.S
index 8bef183fede..de969dd9909 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/getcontext.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/getcontext.S
@@ -71,6 +71,12 @@ ENTRY(__getcontext)
 	/* Store general purpose registers.  */
 	stm     %r0,%r15,SC_GPRS(%r1)
 
+	/* Store psw mask to 0x0 and addr to return address.  Then the address
+	   can be retrieved from the ucontext structure in the same way as if it
+	   is created by kernel and passed to a signal-handler.  */
+	st	%r2,SC_PSW+0(%r1)
+	st	%r14,SC_PSW+4(%r1)
+
 	/* Return.  */
 	br	%r14
 END(__getcontext)
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/makecontext.c b/sysdeps/unix/sysv/linux/s390/s390-32/makecontext.c
index 1f35ffa5ebc..6458ca5f3d2 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/makecontext.c
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/makecontext.c
@@ -60,6 +60,11 @@ __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
 
   /* Set the return address to trampoline.  */
   ucp->uc_mcontext.gregs[14] = (long int) __makecontext_ret;
+  /* Store psw mask to 0x0 and addr to trampoline.  Then the address
+     can be retrieved from the ucontext structure in the same way as if it
+     is created by kernel and passed to a signal-handler.  */
+  ucp->uc_mcontext.psw.addr = (long int) __makecontext_ret;
+  ucp->uc_mcontext.psw.mask = 0;
 
   /* Set register parameters.  */
   va_start (ap, argc);
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/swapcontext.S b/sysdeps/unix/sysv/linux/s390/s390-32/swapcontext.S
index b3f2a8b3446..ccf4d7a935c 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/swapcontext.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/swapcontext.S
@@ -66,6 +66,12 @@ ENTRY(__swapcontext)
 	/* Store general purpose registers.  */
 	stm     %r0,%r15,SC_GPRS(%r1)
 
+	/* Store psw mask to 0x0 and addr to return address.  Then the address
+	   can be retrieved from the ucontext structure in the same way as if it
+	   is created by kernel and passed to a signal-handler.  */
+	st	%r2,SC_PSW+0(%r1)
+	st	%r14,SC_PSW+4(%r1)
+
 	/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, &oucp->uc_sigmask,
 	   sigsetsize).  */
 	la      %r2,SIG_SETMASK
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/getcontext.S b/sysdeps/unix/sysv/linux/s390/s390-64/getcontext.S
index bda313cb230..683f8bb9857 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/getcontext.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/getcontext.S
@@ -71,6 +71,12 @@ ENTRY(__getcontext)
 	/* Store general purpose registers.  */
 	stmg    %r0,%r15,SC_GPRS(%r1)
 
+	/* Store psw mask to 0x0 and addr to return address.  Then the address
+	   can be retrieved from the ucontext structure in the same way as if it
+	   is created by kernel and passed to a signal-handler.  */
+	stg	%r2,SC_PSW+0(%r1)
+	stg	%r14,SC_PSW+8(%r1)
+
 	/* Return.  */
 	br	%r14
 END(__getcontext)
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/makecontext.c b/sysdeps/unix/sysv/linux/s390/s390-64/makecontext.c
index 1dc1af8dc90..b69ff5a136e 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/makecontext.c
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/makecontext.c
@@ -60,6 +60,11 @@ __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
 
   /* Set the return address to trampoline.  */
   ucp->uc_mcontext.gregs[14] = (long int) __makecontext_ret;
+  /* Store psw mask to 0x0 and addr to trampoline.  Then the address
+     can be retrieved from the ucontext structure in the same way as if it
+     is created by kernel and passed to a signal-handler.  */
+  ucp->uc_mcontext.psw.addr = (long int) __makecontext_ret;
+  ucp->uc_mcontext.psw.mask = 0;
 
   /* Set register parameters.  */
   va_start (ap, argc);
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/swapcontext.S b/sysdeps/unix/sysv/linux/s390/s390-64/swapcontext.S
index eaa4f3ba195..4bf85c152c9 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/swapcontext.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/swapcontext.S
@@ -66,6 +66,12 @@ ENTRY(__swapcontext)
 	/* Store general purpose registers.  */
 	stmg    %r0,%r15,SC_GPRS(%r1)
 
+	/* Store psw mask to 0x0 and addr to return address.  Then the address
+	   can be retrieved from the ucontext structure in the same way as if it
+	   is created by kernel and passed to a signal-handler.  */
+	stg	%r2,SC_PSW+0(%r1)
+	stg	%r14,SC_PSW+8(%r1)
+
 	/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, &oucp->uc_sigmask,
 	   sigsetsize).  */
 	la      %r2,SIG_SETMASK