6.15-stable review patch. If anyone has any objections, please let me know.
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From: Jeremy Linton jeremy.linton@arm.com
[ Upstream commit cbbcfb94c55c02a8c4ce52b5da0770b5591a314c ]
Mark Rutland noticed that the task parameter is ignored and 'current' is being used instead. Since this is usually what its passed, it hasn't yet been causing problems but likely will as the code gets more testing.
But, once this is fixed, it creates a new bug in copy_thread_gcs() since the gcs_el_mode isn't yet set for the task before its being checked. Move gcs_alloc_thread_stack() after the new task's gcs_el0_mode initialization to avoid this.
Fixes: fc84bc5378a8 ("arm64/gcs: Context switch GCS state for EL0") Signed-off-by: Jeremy Linton jeremy.linton@arm.com Reviewed-by: Mark Brown broonie@kernel.org Link: https://lore.kernel.org/r/20250719043740.4548-2-jeremy.linton@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/include/asm/gcs.h | 2 +- arch/arm64/kernel/process.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/include/asm/gcs.h b/arch/arm64/include/asm/gcs.h index f50660603ecf..5bc432234d3a 100644 --- a/arch/arm64/include/asm/gcs.h +++ b/arch/arm64/include/asm/gcs.h @@ -58,7 +58,7 @@ static inline u64 gcsss2(void)
static inline bool task_gcs_el0_enabled(struct task_struct *task) { - return current->thread.gcs_el0_mode & PR_SHADOW_STACK_ENABLE; + return task->thread.gcs_el0_mode & PR_SHADOW_STACK_ENABLE; }
void gcs_set_el0_mode(struct task_struct *task); diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 4bc70205312e..ce21682fe129 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -305,13 +305,13 @@ static int copy_thread_gcs(struct task_struct *p, p->thread.gcs_base = 0; p->thread.gcs_size = 0;
+ p->thread.gcs_el0_mode = current->thread.gcs_el0_mode; + p->thread.gcs_el0_locked = current->thread.gcs_el0_locked; + gcs = gcs_alloc_thread_stack(p, args); if (IS_ERR_VALUE(gcs)) return PTR_ERR((void *)gcs);
- p->thread.gcs_el0_mode = current->thread.gcs_el0_mode; - p->thread.gcs_el0_locked = current->thread.gcs_el0_locked; - return 0; }