| Message ID | fbf47d394de6bd7332b00bc706a9f38cd7a68327.1386879684.git.geoff@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Dec 12, 2013 at 08:39:46PM +0000, Geoff Levand wrote: > Change the soft_restart() routine to call cpu_reset() at its identity mapped > physical address. > > The cpu_reset() routine must be called at its identity mapped physical address > so that when the MMU is turned off the instruction pointer will be at the correct > location in physical memory. > > Signed-off-by: Geoff Levand <geoff@infradead.org> for Huawei, Linaro > --- > arch/arm64/kernel/process.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index de17c89..985eb42 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -72,7 +72,13 @@ static void setup_restart(void) > void soft_restart(unsigned long addr) > { > setup_restart(); > - cpu_reset(addr); > + > + /* > + * cpu_reset turns the MMU off, so must be called at its identity > + * mapped physical address. > + */ > + > + (*(void(*)(unsigned long))virt_to_phys(cpu_reset))(addr); This isn't right; although cpu_reset *does* need to run from the idmap, actually the idmap only includes __turn_mmu_on. You just get lucky because its section-mapped and happens to include the code you want. The cast is also cleaner if you define a phys_reset_t type, like we do for arch/arm/. Will
Hi Will, On Fri, 2013-12-13 at 16:46 +0000, Will Deacon wrote: > On Thu, Dec 12, 2013 at 08:39:46PM +0000, Geoff Levand wrote: > > + /* > > + * cpu_reset turns the MMU off, so must be called at its identity > > + * mapped physical address. > > + */ > > + > > + (*(void(*)(unsigned long))virt_to_phys(cpu_reset))(addr); > > This isn't right; although cpu_reset *does* need to run from the idmap, > actually the idmap only includes __turn_mmu_on. You just get lucky because > its section-mapped and happens to include the code you want. OK, I think this is different from fixing the call in soft_restart(), so I'll make a separate patch for this. I can see a few ways to do it but am not sure of the ramifications of each. Should we put cpu_reset into the idmap at startup when we add __turn_mmu_on, or add cpu_reset on demand from say setup_mm_for_reboot()? If the former, is all we need something like this? @@ -438,6 +438,9 @@ __create_page_tables: adr x3, __turn_mmu_on // virtual/physical address create_pgd_entry x25, x0, x3, x5, x6 create_block_map x0, x7, x3, x5, x5, idmap=1 + adr x3, cpu_reset // virtual/physical address + create_pgd_entry x25, x0, x3, x5, x6 + create_block_map x0, x7, x3, x5, x5, idmap=1 > The cast is also cleaner if you define a phys_reset_t type, like we do for > arch/arm/. I'll send out an updated fix. -Geoff
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index de17c89..985eb42 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -72,7 +72,13 @@ static void setup_restart(void) void soft_restart(unsigned long addr) { setup_restart(); - cpu_reset(addr); + + /* + * cpu_reset turns the MMU off, so must be called at its identity + * mapped physical address. + */ + + (*(void(*)(unsigned long))virt_to_phys(cpu_reset))(addr); } /*
Change the soft_restart() routine to call cpu_reset() at its identity mapped physical address. The cpu_reset() routine must be called at its identity mapped physical address so that when the MMU is turned off the instruction pointer will be at the correct location in physical memory. Signed-off-by: Geoff Levand <geoff@infradead.org> for Huawei, Linaro --- arch/arm64/kernel/process.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)