Re: [PATCH] powerpc/32: Clear volatile regs on syscall exit

2022-02-24 Thread Segher Boessenkool
Hi! On Thu, Feb 24, 2022 at 09:29:55AM +0100, Gabriel Paubert wrote: > On Wed, Feb 23, 2022 at 05:27:39PM -0600, Segher Boessenkool wrote: > > On Wed, Feb 23, 2022 at 09:48:09PM +0100, Gabriel Paubert wrote: > > > On Wed, Feb 23, 2022 at 06:11:36PM +0100, Christophe Leroy wrote: > > > > + /*

Re: [PATCH] powerpc/32: Clear volatile regs on syscall exit

2022-02-24 Thread Segher Boessenkool
On Wed, Feb 23, 2022 at 09:48:09PM +0100, Gabriel Paubert wrote: > On Wed, Feb 23, 2022 at 06:11:36PM +0100, Christophe Leroy wrote: > > + /* Zero volatile regs that may contain sensitive kernel data */ > > + li r0,0 > > + li r4,0 > > + li r5,0 > > + li r6,0 > > + li

Re: [PATCH] powerpc/32: Clear volatile regs on syscall exit

2022-02-24 Thread Christophe Leroy
Le 23/02/2022 à 20:34, Kees Cook a écrit : > On Wed, Feb 23, 2022 at 06:11:36PM +0100, Christophe Leroy wrote: >> Commit a82adfd5c7cb ("hardening: Introduce CONFIG_ZERO_CALL_USED_REGS") >> added zeroing of used registers at function exit. >> >> At the time being, PPC64 clears volatile registers o

Re: [PATCH] powerpc/32: Clear volatile regs on syscall exit

2022-02-24 Thread Gabriel Paubert
On Wed, Feb 23, 2022 at 05:27:39PM -0600, Segher Boessenkool wrote: > On Wed, Feb 23, 2022 at 09:48:09PM +0100, Gabriel Paubert wrote: > > On Wed, Feb 23, 2022 at 06:11:36PM +0100, Christophe Leroy wrote: > > > + /* Zero volatile regs that may contain sensitive kernel data */ > > > + li r0,0 >

Re: [PATCH] powerpc/32: Clear volatile regs on syscall exit

2022-02-24 Thread Christophe Leroy
Le 23/02/2022 à 21:48, Gabriel Paubert a écrit : > On Wed, Feb 23, 2022 at 06:11:36PM +0100, Christophe Leroy wrote: >> Commit a82adfd5c7cb ("hardening: Introduce CONFIG_ZERO_CALL_USED_REGS") >> added zeroing of used registers at function exit. >> >> At the time being, PPC64 clears volatile regis

Re: [PATCH] powerpc/32: Clear volatile regs on syscall exit

2022-02-23 Thread Gabriel Paubert
On Wed, Feb 23, 2022 at 06:11:36PM +0100, Christophe Leroy wrote: > Commit a82adfd5c7cb ("hardening: Introduce CONFIG_ZERO_CALL_USED_REGS") > added zeroing of used registers at function exit. > > At the time being, PPC64 clears volatile registers on syscall exit but > PPC32 doesn't do it for perfo

Re: [PATCH] powerpc/32: Clear volatile regs on syscall exit

2022-02-23 Thread Kees Cook
On Wed, Feb 23, 2022 at 06:11:36PM +0100, Christophe Leroy wrote: > Commit a82adfd5c7cb ("hardening: Introduce CONFIG_ZERO_CALL_USED_REGS") > added zeroing of used registers at function exit. > > At the time being, PPC64 clears volatile registers on syscall exit but > PPC32 doesn't do it for perfo

[PATCH] powerpc/32: Clear volatile regs on syscall exit

2022-02-23 Thread Christophe Leroy
Commit a82adfd5c7cb ("hardening: Introduce CONFIG_ZERO_CALL_USED_REGS") added zeroing of used registers at function exit. At the time being, PPC64 clears volatile registers on syscall exit but PPC32 doesn't do it for performance reason. Add that clearing in PPC32 syscall exit as well, but only wh