[glibc/release/2.42/master] tests: fix tst-rseq with Linux 7.0

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a56a2943d2ce541102c630142c2eae0fbfc5886b

commit a56a2943d2ce541102c630142c2eae0fbfc5886b
Author: Michael Jeanson <[email protected]>
Date:   Fri Feb 20 11:01:00 2026 -0500

    tests: fix tst-rseq with Linux 7.0
    
    A sub-test of tst-rseq is to validate the return code and errno of the
    rseq syscall when attempting to register the exact same rseq area as was
    done in the dynamic loader.
    
    This involves finding the rseq area address by adding the
    '__rseq_offset' to the thread pointer and calculating the area size from
    the AT_RSEQ_FEATURE_SIZE auxiliary vector. However the test currently
    calculates the size of the rseq area allocation in the TLS block which
    must be a multiple of AT_RSEQ_ALIGN.
    
    Up until now that happened to be the same value since the feature size
    and alignment exposed by the kernel were below the minimum ABI size of
    32. Starting with Linux 7.0 the feature size has reached 33 while the
    alignment is now 64.
    
    This results in the test trying to re-register the rseq area with a
    different size and thus not getting the expected errno value.
    
    Signed-off-by: Michael Jeanson <[email protected]>
    Reviewed-by: Mathieu Desnoyers <[email protected]>
    (cherry picked from commit 67f303b47dc584f204e3f2441b9832082415eebc)

Diff:
---
 sysdeps/unix/sysv/linux/tst-rseq.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/tst-rseq.c b/sysdeps/unix/sysv/linux/tst-rseq.c
index 00181cfefb..e83ea2b939 100644
--- a/sysdeps/unix/sysv/linux/tst-rseq.c
+++ b/sysdeps/unix/sysv/linux/tst-rseq.c
@@ -48,8 +48,7 @@ do_rseq_main_test (void)
   size_t rseq_align = MAX (getauxval (AT_RSEQ_ALIGN), RSEQ_MIN_ALIGN);
   size_t rseq_feature_size = MAX (getauxval (AT_RSEQ_FEATURE_SIZE),
                                   RSEQ_AREA_SIZE_INITIAL_USED);
-  size_t rseq_alloc_size = roundup (MAX (rseq_feature_size,
-                                    RSEQ_AREA_SIZE_INITIAL_USED), rseq_align);
+  size_t rseq_reg_size = MAX (rseq_feature_size, RSEQ_AREA_SIZE_INITIAL);
   struct rseq *rseq_abi = __thread_pointer () + __rseq_offset;
 
   TEST_VERIFY_EXIT (rseq_thread_registered ());
@@ -89,8 +88,8 @@ do_rseq_main_test (void)
   /* Test a rseq registration with the same arguments as the internal
      registration which should fail with errno == EBUSY.  */
   TEST_VERIFY (((unsigned long) rseq_abi % rseq_align) == 0);
-  TEST_VERIFY (__rseq_size <= rseq_alloc_size);
-  int ret = syscall (__NR_rseq, rseq_abi, rseq_alloc_size, 0, RSEQ_SIG);
+  TEST_VERIFY (__rseq_size <= rseq_reg_size);
+  int ret = syscall (__NR_rseq, rseq_abi, rseq_reg_size, 0, RSEQ_SIG);
   TEST_VERIFY (ret != 0);
   TEST_COMPARE (errno, EBUSY);
 }