[PATCHv4 07/10] kexec: Switch to __pa_symbol

[Laura Abbott]

__pa_symbol is the correct api to get the physical address of kernel
symbols. Switch to it to allow for better debug checking.

Signed-off-by: Laura Abbott <***@redhat.com>
---
Found during review of the kernel. Untested.
---
kernel/kexec_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 5616755..e1b625e 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1397,7 +1397,7 @@ void __weak arch_crash_save_vmcoreinfo(void)

phys_addr_t __weak paddr_vmcoreinfo_note(void)
{
- return __pa((unsigned long)(char *)&vmcoreinfo_note);
+ return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note);
}

static int __init crash_save_vmcoreinfo_init(void)

[Dave Young]

Hi, Laura

Post by Laura Abbott
__pa_symbol is the correct api to get the physical address of kernel
symbols. Switch to it to allow for better debug checking.

I assume __pa_symbol is faster than __pa, but it still need some testing
on all arches which support kexec.

But seems long long ago there is a commit e3ebadd95cb in the commit log
I see below from:
"we should deprecate __pa_symbol(), and preferably __pa() too - and
just use "virt_to_phys()" instead, which is is more readable and has
nicer semantics."

But maybe in modern code __pa_symbol is prefered I may miss background.
virt_to_phys still sounds more readable now for me though.

Post by Laura Abbott
---
Found during review of the kernel. Untested.
---
kernel/kexec_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 5616755..e1b625e 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1397,7 +1397,7 @@ void __weak arch_crash_save_vmcoreinfo(void)
phys_addr_t __weak paddr_vmcoreinfo_note(void)
{
- return __pa((unsigned long)(char *)&vmcoreinfo_note);
+ return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note);
}
static int __init crash_save_vmcoreinfo_init(void)
--
2.7.4
_______________________________________________
kexec mailing list
http://lists.infradead.org/mailman/listinfo/kexec

Thanks
Dave

[Eric W. Biederman]

Post by Dave Young
Hi, Laura

Post by Laura Abbott
__pa_symbol is the correct api to get the physical address of kernel
symbols. Switch to it to allow for better debug checking.

I assume __pa_symbol is faster than __pa, but it still need some testing
on all arches which support kexec.
But seems long long ago there is a commit e3ebadd95cb in the commit log
"we should deprecate __pa_symbol(), and preferably __pa() too - and
just use "virt_to_phys()" instead, which is is more readable and has
nicer semantics."
But maybe in modern code __pa_symbol is prefered I may miss background.
virt_to_phys still sounds more readable now for me though.

There has been a lot of history with the various definitions.
__pa_symbol used to be x86 specific.

Now what we have is that __pa_symbol is just __pa(RELOC_HIDE(x));

Now arguably that whole reloc hide thing should happen by architectures
having a non-inline version of __pa as was done in the commit you
mention. But at this point there appears to be nothing wrong with
changing a __pa to a __pa_symbol it might make things a tad more
reliable depending on the implementation of __pa.

Acked-by: "Eric W. Biederman" <***@xmission.com>


Eric

Post by Dave Young

Post by Laura Abbott
---
Found during review of the kernel. Untested.
---
kernel/kexec_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 5616755..e1b625e 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1397,7 +1397,7 @@ void __weak arch_crash_save_vmcoreinfo(void)
phys_addr_t __weak paddr_vmcoreinfo_note(void)
{
- return __pa((unsigned long)(char *)&vmcoreinfo_note);
+ return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note);
}
static int __init crash_save_vmcoreinfo_init(void)
--
2.7.4
_______________________________________________
kexec mailing list
http://lists.infradead.org/mailman/listinfo/kexec

Thanks
Dave

[Dave Young]

Post by Eric W. Biederman

Post by Dave Young
Hi, Laura

Post by Laura Abbott
__pa_symbol is the correct api to get the physical address of kernel
symbols. Switch to it to allow for better debug checking.

I assume __pa_symbol is faster than __pa, but it still need some testing
on all arches which support kexec.
But seems long long ago there is a commit e3ebadd95cb in the commit log
"we should deprecate __pa_symbol(), and preferably __pa() too - and
just use "virt_to_phys()" instead, which is is more readable and has
nicer semantics."
But maybe in modern code __pa_symbol is prefered I may miss background.
virt_to_phys still sounds more readable now for me though.

There has been a lot of history with the various definitions.
__pa_symbol used to be x86 specific.
Now what we have is that __pa_symbol is just __pa(RELOC_HIDE(x));
Now arguably that whole reloc hide thing should happen by architectures
having a non-inline version of __pa as was done in the commit you
mention. But at this point there appears to be nothing wrong with
changing a __pa to a __pa_symbol it might make things a tad more
reliable depending on the implementation of __pa.

Then it is safe and reasonable, thanks for the clarification.

Post by Eric W. Biederman
Eric

Post by Dave Young

Post by Laura Abbott
---
Found during review of the kernel. Untested.
---
kernel/kexec_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 5616755..e1b625e 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1397,7 +1397,7 @@ void __weak arch_crash_save_vmcoreinfo(void)
phys_addr_t __weak paddr_vmcoreinfo_note(void)
{
- return __pa((unsigned long)(char *)&vmcoreinfo_note);
+ return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note);
}
static int __init crash_save_vmcoreinfo_init(void)
--
2.7.4
_______________________________________________
kexec mailing list
http://lists.infradead.org/mailman/listinfo/kexec

Thanks
Dave