Re: [PATCH v6 08/13] arm64: expose user PAC bit positions via ptrace

2018-12-10 Thread Catalin Marinas
On Mon, Dec 10, 2018 at 02:29:45PM +, Will Deacon wrote: > On Mon, Dec 10, 2018 at 08:22:06AM -0600, Richard Henderson wrote: > > On 12/10/18 6:03 AM, Catalin Marinas wrote: > > >> However, it won't be too long before someone implements support for > > >> ARMv8.2-LVA, at which point, without ch

Re: [PATCH v6 08/13] arm64: expose user PAC bit positions via ptrace

2018-12-10 Thread Will Deacon
On Mon, Dec 10, 2018 at 08:22:06AM -0600, Richard Henderson wrote: > On 12/10/18 6:03 AM, Catalin Marinas wrote: > >> However, it won't be too long before someone implements support for > >> ARMv8.2-LVA, at which point, without changes to mandatory pointer tagging, > >> we > >> will only have 3 au

Re: [PATCH v6 08/13] arm64: expose user PAC bit positions via ptrace

2018-12-10 Thread Richard Henderson
On 12/10/18 6:03 AM, Catalin Marinas wrote: >> However, it won't be too long before someone implements support for >> ARMv8.2-LVA, at which point, without changes to mandatory pointer tagging, we >> will only have 3 authentication bits: [54:52]. This seems useless and easily >> brute-force-able. >

Re: [PATCH v6 08/13] arm64: expose user PAC bit positions via ptrace

2018-12-10 Thread Catalin Marinas
On Sun, Dec 09, 2018 at 09:41:31AM -0600, Richard Henderson wrote: > On 12/7/18 12:39 PM, Kristina Martsenko wrote: > > 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 configu

Re: [PATCH v6 08/13] arm64: expose user PAC bit positions via ptrace

2018-12-09 Thread Richard Henderson
On 12/7/18 12:39 PM, Kristina Martsenko wrote: > 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 t

Re: [PATCH v6 08/13] arm64: expose user PAC bit positions via ptrace

2018-12-09 Thread Richard Henderson
On 12/7/18 12:39 PM, Kristina Martsenko wrote: > From: Mark Rutland > > 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.

[PATCH v6 08/13] arm64: expose user PAC bit positions via ptrace

2018-12-07 Thread Kristina Martsenko
From: Mark Rutland 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