[RFC,03/29] arm64: signal: factor out signal frame record allocation
Commit Message
Factor out the allocator for signal frame optional records into a
separate function, to ensure consistency and facilitate later
expansion of the signal frame.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
---
arch/arm64/kernel/signal.c | 43 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 36 insertions(+), 7 deletions(-)
@@ -75,6 +75,22 @@ static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
}
+/*
+ * Allocate space for an optional record of <size> bytes in the user
+ * signal frame. The offset from the signal frame base address to the
+ * allocated block is assigned to *offset.
+ */
+static int sigframe_alloc(struct rt_sigframe_user_layout *user,
+ unsigned long *offset, size_t size)
+{
+ size_t padded_size = round_up(size, 16);
+
+ *offset = user->size;
+ user->size += padded_size;
+
+ return 0;
+}
+
static void __user *apply_user_offset(
struct rt_sigframe_user_layout const *user, unsigned long offset)
{
@@ -283,19 +299,32 @@ asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
/* Determine the layout of optional records in the signal frame */
static int setup_sigframe_layout(struct rt_sigframe_user_layout *user)
{
- user->fpsimd_offset = user->size;
- user->size += round_up(sizeof(struct fpsimd_context), 16);
+ int err;
+
+ err = sigframe_alloc(user, &user->fpsimd_offset,
+ sizeof(struct fpsimd_context));
+ if (err)
+ return err;
/* fault information, if valid */
if (current->thread.fault_code) {
- user->esr_offset = user->size;
- user->size += round_up(sizeof(struct esr_context), 16);
+ err = sigframe_alloc(user, &user->esr_offset,
+ sizeof(struct esr_context));
+ if (err)
+ return err;
}
- /* set the "end" magic */
- user->end_offset = user->size;
+ /*
+ * Allocate space for the terminator record.
+ * HACK: here we undo the reservation of space for the end record.
+ * This bodge should be replaced with a cleaner approach later on.
+ */
+ user->limit = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved) +
+ sizeof(user->sigframe->uc.uc_mcontext.__reserved);
- return 0;
+ err = sigframe_alloc(user, &user->end_offset,
+ sizeof(struct _aarch64_ctx));
+ return err;
}