On 12/7/18 12:39 PM, Kristina Martsenko wrote: > From: Mark Rutland <[email protected]> > > When pointer authentication is in use, data/instruction pointers have a > number of PAC bits inserted into them. The number and position of these > bits depends on the configured TCR_ELx.TxSZ and whether tagging is > enabled. ARMv8.3 allows tagging to differ for instruction and data > pointers. > > For userspace debuggers to unwind the stack and/or to follow pointer > chains, they need to be able to remove the PAC bits before attempting to > use a pointer. > > This patch adds a new structure with masks describing the location of > the PAC bits in userspace instruction and data pointers (i.e. those > addressable via TTBR0), which userspace can query via PTRACE_GETREGSET. > By clearing these bits from pointers (and replacing them with the value > of bit 55), userspace can acquire the PAC-less versions. > > This new regset is exposed when the kernel is built with (user) pointer > authentication support, and the address authentication feature is > enabled. Otherwise, the regset is hidden. > > Signed-off-by: Mark Rutland <[email protected]> > Signed-off-by: Kristina Martsenko <[email protected]> > Cc: Catalin Marinas <[email protected]> > Cc: Ramana Radhakrishnan <[email protected]> > Cc: Will Deacon <[email protected]> > --- > arch/arm64/include/asm/pointer_auth.h | 8 ++++++++ > arch/arm64/include/uapi/asm/ptrace.h | 7 +++++++ > arch/arm64/kernel/ptrace.c | 38 > +++++++++++++++++++++++++++++++++++ > include/uapi/linux/elf.h | 1 + > 4 files changed, 54 insertions(+)
Reviewed-by: Richard Henderson <[email protected]> r~
