| Message ID | 1464706504-25224-3-git-send-email-catalin.marinas@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, May 31, 2016 at 03:55:04PM +0100, Catalin Marinas wrote: > Currently, the compat /proc/cpuinfo is provided only if a task has the > PER_LINUX32 personality, either by setting it explicitly or by > inheriting it from the parent task. This is in line with the "uname -m" > behaviour. > > However, there are 32-bit user applications making use of the > /proc/cpuinfo and unaware of a need to set the personality. This patch > changes the arm64 /proc/cpuinfo logic to provide the compat information > if the task is 32-bit _or_ the PER_LINUX32 personality is set. > > Cc: <stable@vger.kernel.org> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Will Deacon <will.deacon@arm.com> > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > --- > arch/arm64/kernel/cpuinfo.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c > index c173d329397f..bd6a122ea856 100644 > --- a/arch/arm64/kernel/cpuinfo.c > +++ b/arch/arm64/kernel/cpuinfo.c > @@ -106,7 +106,8 @@ static const char *const compat_hwcap2_str[] = { > static int c_show(struct seq_file *m, void *v) > { > int i, j; > - bool compat = personality(current->personality) == PER_LINUX32; > + bool compat = is_compat_task() || > + personality(current->personality) == PER_LINUX32; Hmm, I'm uneasy about this. It feels like an inconsistency with other things like uname, where we require the personality to be changed explicitly in order to get the AArch32 interface. I'd rather go back to changing personality automatically based on the elf machine, or continue to require that applications be run with the correct personality (e.g. via linux32). This half way house is just confusing. Arnd might have more thoughts... Will
Hi all, On Tue, May 31, 2016 at 03:55:04PM +0100, Catalin Marinas wrote: > Currently, the compat /proc/cpuinfo is provided only if a task has the > PER_LINUX32 personality, either by setting it explicitly or by > inheriting it from the parent task. This is in line with the "uname -m" > behaviour. > > However, there are 32-bit user applications making use of the > /proc/cpuinfo and unaware of a need to set the personality. This patch > changes the arm64 /proc/cpuinfo logic to provide the compat information > if the task is 32-bit _or_ the PER_LINUX32 personality is set. > > Cc: <stable@vger.kernel.org> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Will Deacon <will.deacon@arm.com> > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> What's the status on this patch? The previous patch (which was accepted already) is indeed confusing, because ARM32 processes on an ARM64 system are not necessarily setting PER_LINUX32. I'm also curious, why was 'model name' removed from ARM64 in the first place? Plenty of other architectures support a similar property, and it's useful for some tools that already parse this, such as coreutils `uname -p` on Gentoo (and presumably others -- my Ubuntu machine must be similarly patched, as it supports `uname -p` on x86_64). If we were to just stick 'model name' back in unconditionally, we could avoid the objections Will raised entirely :) Regards, Brian > --- > arch/arm64/kernel/cpuinfo.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c > index c173d329397f..bd6a122ea856 100644 > --- a/arch/arm64/kernel/cpuinfo.c > +++ b/arch/arm64/kernel/cpuinfo.c > @@ -106,7 +106,8 @@ static const char *const compat_hwcap2_str[] = { > static int c_show(struct seq_file *m, void *v) > { > int i, j; > - bool compat = personality(current->personality) == PER_LINUX32; > + bool compat = is_compat_task() || > + personality(current->personality) == PER_LINUX32; > > for_each_online_cpu(i) { > struct cpuinfo_arm64 *cpuinfo = &per_cpu(cpu_data, i);
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index c173d329397f..bd6a122ea856 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -106,7 +106,8 @@ static const char *const compat_hwcap2_str[] = { static int c_show(struct seq_file *m, void *v) { int i, j; - bool compat = personality(current->personality) == PER_LINUX32; + bool compat = is_compat_task() || + personality(current->personality) == PER_LINUX32; for_each_online_cpu(i) { struct cpuinfo_arm64 *cpuinfo = &per_cpu(cpu_data, i);
Currently, the compat /proc/cpuinfo is provided only if a task has the PER_LINUX32 personality, either by setting it explicitly or by inheriting it from the parent task. This is in line with the "uname -m" behaviour. However, there are 32-bit user applications making use of the /proc/cpuinfo and unaware of a need to set the personality. This patch changes the arm64 /proc/cpuinfo logic to provide the compat information if the task is 32-bit _or_ the PER_LINUX32 personality is set. Cc: <stable@vger.kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> --- arch/arm64/kernel/cpuinfo.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)