[glibc] s390: Set psw addr field in getcontext and friends.

[Stefan Liebler <stli@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=664f565f9caa26bb128bad7d7050cf0f0b9c6322

commit 664f565f9caa26bb128bad7d7050cf0f0b9c6322
Author: Stefan Liebler <stli@linux.ibm.com>
Date:   Fri Dec 15 09:26:40 2023 +0100

    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:
---
 sysdeps/unix/sysv/linux/s390/s390-32/getcontext.S  | 6 ++++++
 sysdeps/unix/sysv/linux/s390/s390-32/makecontext.c | 5 +++++
 sysdeps/unix/sysv/linux/s390/s390-32/swapcontext.S | 6 ++++++
 sysdeps/unix/sysv/linux/s390/s390-64/getcontext.S  | 6 ++++++
 sysdeps/unix/sysv/linux/s390/s390-64/makecontext.c | 5 +++++
 sysdeps/unix/sysv/linux/s390/s390-64/swapcontext.S | 6 ++++++
 6 files changed, 34 insertions(+)

diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/getcontext.S b/sysdeps/unix/sysv/linux/s390/s390-32/getcontext.S
index 8bef183fed..de969dd990 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 1f35ffa5eb..6458ca5f3d 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 b3f2a8b344..ccf4d7a935 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 bda313cb23..683f8bb985 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 1dc1af8dc9..b69ff5a136 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 eaa4f3ba19..4bf85c152c 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