| Message ID | 20190723213553.22300-5-julien.grall@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | xen/arm: Xen hardening for newer Armv8 | expand |
Julien Grall writes: > At the moment, _show_registers() is using a BUG_ON() to assert only > userspace will run 32-bit code in a 64-bit domain. > > Such extra precaution is not necessary and could be avoided by only > checking the CPU mode to decide whether show_registers_64() or > show_reigsters_32() should be called. > > This has also the nice advantage to avoid nested if in the code. > > Signed-off-by: Julien Grall <julien.grall@arm.com> Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com> > --- > xen/arch/arm/traps.c | 16 +++------------- > 1 file changed, 3 insertions(+), 13 deletions(-) > > diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c > index 54e66a86d0..132686ee0f 100644 > --- a/xen/arch/arm/traps.c > +++ b/xen/arch/arm/traps.c > @@ -914,21 +914,11 @@ static void _show_registers(const struct cpu_user_regs *regs, > > if ( guest_mode ) > { > - if ( is_32bit_domain(v->domain) ) > + if ( psr_mode_is_32bit(regs) ) > show_registers_32(regs, ctxt, guest_mode, v); > #ifdef CONFIG_ARM_64 > - else if ( is_64bit_domain(v->domain) ) > - { > - if ( psr_mode_is_32bit(regs) ) > - { > - BUG_ON(!usr_mode(regs)); > - show_registers_32(regs, ctxt, guest_mode, v); > - } > - else > - { > - show_registers_64(regs, ctxt, guest_mode, v); > - } > - } > + else > + show_registers_64(regs, ctxt, guest_mode, v); > #endif > } > else
On Fri, 26 Jul 2019, Volodymyr Babchuk wrote: > Julien Grall writes: > > > At the moment, _show_registers() is using a BUG_ON() to assert only > > userspace will run 32-bit code in a 64-bit domain. > > > > Such extra precaution is not necessary and could be avoided by only > > checking the CPU mode to decide whether show_registers_64() or > > show_reigsters_32() should be called. > > > > This has also the nice advantage to avoid nested if in the code. > > > > Signed-off-by: Julien Grall <julien.grall@arm.com> > Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com> Acked-by: Stefano Stabellini <sstabellini@kernel.org> > > --- > > xen/arch/arm/traps.c | 16 +++------------- > > 1 file changed, 3 insertions(+), 13 deletions(-) > > > > diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c > > index 54e66a86d0..132686ee0f 100644 > > --- a/xen/arch/arm/traps.c > > +++ b/xen/arch/arm/traps.c > > @@ -914,21 +914,11 @@ static void _show_registers(const struct cpu_user_regs *regs, > > > > if ( guest_mode ) > > { > > - if ( is_32bit_domain(v->domain) ) > > + if ( psr_mode_is_32bit(regs) ) > > show_registers_32(regs, ctxt, guest_mode, v); > > #ifdef CONFIG_ARM_64 > > - else if ( is_64bit_domain(v->domain) ) > > - { > > - if ( psr_mode_is_32bit(regs) ) > > - { > > - BUG_ON(!usr_mode(regs)); > > - show_registers_32(regs, ctxt, guest_mode, v); > > - } > > - else > > - { > > - show_registers_64(regs, ctxt, guest_mode, v); > > - } > > - } > > + else > > + show_registers_64(regs, ctxt, guest_mode, v); > > #endif > > } > > else > > > -- > Volodymyr Babchuk at EPAM
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c index 54e66a86d0..132686ee0f 100644 --- a/xen/arch/arm/traps.c +++ b/xen/arch/arm/traps.c @@ -914,21 +914,11 @@ static void _show_registers(const struct cpu_user_regs *regs, if ( guest_mode ) { - if ( is_32bit_domain(v->domain) ) + if ( psr_mode_is_32bit(regs) ) show_registers_32(regs, ctxt, guest_mode, v); #ifdef CONFIG_ARM_64 - else if ( is_64bit_domain(v->domain) ) - { - if ( psr_mode_is_32bit(regs) ) - { - BUG_ON(!usr_mode(regs)); - show_registers_32(regs, ctxt, guest_mode, v); - } - else - { - show_registers_64(regs, ctxt, guest_mode, v); - } - } + else + show_registers_64(regs, ctxt, guest_mode, v); #endif } else
At the moment, _show_registers() is using a BUG_ON() to assert only userspace will run 32-bit code in a 64-bit domain. Such extra precaution is not necessary and could be avoided by only checking the CPU mode to decide whether show_registers_64() or show_reigsters_32() should be called. This has also the nice advantage to avoid nested if in the code. Signed-off-by: Julien Grall <julien.grall@arm.com> --- xen/arch/arm/traps.c | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-)