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kselftest/arm64: tpidr2: Adjust to new clone() behaviour

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In order to fix an ABI problem, we recently changed the way that a
clone() syscall manipulates TPIDR2 and PSTATE.ZA. Historically the child
would inherit the parent's TPIDR2 value unless CLONE_SETTLS was set, and
now the child will inherit the parent's TPIDR2 value unless CLONE_VM is
set.

Update the tpidr2 test for the new behaviour.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Kiss <daniel.kiss@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Richard Sandiford <richard.sandiford@arm.com>
Cc: Sander De Smalen <sander.desmalen@arm.com>
Cc: Tamas Petz <tamas.petz@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yury Khrustalev <yury.khrustalev@arm.com>
Link: https://lore.kernel.org/r/20250508132644.1395904-23-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Mark Rutland 2025-05-08 14:26:42 +01:00 committed by Will Deacon
parent 78b23877db
commit be45e63f79
1 changed files with 12 additions and 2 deletions
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14
tools/testing/selftests/arm64/abi/tpidr2.c
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@ -169,8 +169,10 @@ static int sys_clone(unsigned long clone_flags, unsigned long newsp,
child_tidptr);
}
#define __STACK_SIZE (8 * 1024 * 1024)
/*
* If we clone with CLONE_SETTLS then the value in the parent should
* If we clone with CLONE_VM then the value in the parent should
* be unchanged and the child should start with zero and be able to
* set its own value.
*/
@ -179,11 +181,19 @@ static int write_clone_read(void)
int parent_tid, child_tid;
pid_t parent, waiting;
int ret, status;
void *stack;
parent = getpid();
set_tpidr2(parent);
ret = sys_clone(CLONE_SETTLS, 0, &parent_tid, 0, &child_tid);
stack = malloc(__STACK_SIZE);
if (!stack) {
putstr("# malloc() failed\n");
return 0;
}
ret = sys_clone(CLONE_VM, (unsigned long)stack + __STACK_SIZE,
&parent_tid, 0, &child_tid);
if (ret == -1) {
putstr("# clone() failed\n");
putnum(errno);