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| author |   John David Anglin <dave.anglin@bell.net> | 2019-06-02 19:12:40 -0400 |
|---|---|---|
| committer |   Helge Deller <deller@gmx.de> | 2019-06-06 14:12:22 +0200 |
| commit | 116d753308cf032159c7b7aa87c9605bb5354784 (patch) | |
| tree | f2642cc73c48384f7b7934d0c794d27121018ffd /arch | |
| parent | parisc: configs: Remove useless UEVENT_HELPER_PATH (diff) | |
| download | linux-dev-116d753308cf032159c7b7aa87c9605bb5354784.tar.xz linux-dev-116d753308cf032159c7b7aa87c9605bb5354784.zip | |
parisc: Use lpa instruction to load physical addresses in driver code
Most I/O in the kernel is done using the kernel offset mapping.
However, there is one API that uses aliased kernel address ranges:
> The final category of APIs is for I/O to deliberately aliased address
> ranges inside the kernel. Such aliases are set up by use of the
> vmap/vmalloc API. Since kernel I/O goes via physical pages, the I/O
> subsystem assumes that the user mapping and kernel offset mapping are
> the only aliases. This isn't true for vmap aliases, so anything in
> the kernel trying to do I/O to vmap areas must manually manage
> coherency. It must do this by flushing the vmap range before doing
> I/O and invalidating it after the I/O returns.
For this reason, we should use the hardware lpa instruction to load the
physical address of kernel virtual addresses in the driver code.
I believe we only use the vmap/vmalloc API with old PA 1.x processors
which don't have a sba, so we don't hit this problem.
Tested on c3750, c8000 and rp3440.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/parisc/include/asm/special_insns.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/parisc/include/asm/special_insns.h b/arch/parisc/include/asm/special_insns.h index 3d4dd68e181b..a303ae9a77f4 100644 --- a/arch/parisc/include/asm/special_insns.h +++ b/arch/parisc/include/asm/special_insns.h @@ -2,6 +2,30 @@ #ifndef __PARISC_SPECIAL_INSNS_H #define __PARISC_SPECIAL_INSNS_H +#define lpa(va) ({ \ + unsigned long pa; \ + __asm__ __volatile__( \ + "copy %%r0,%0\n\t" \ + "lpa %%r0(%1),%0" \ + : "=r" (pa) \ + : "r" (va) \ + : "memory" \ + ); \ + pa; \ +}) + +#define lpa_user(va) ({ \ + unsigned long pa; \ + __asm__ __volatile__( \ + "copy %%r0,%0\n\t" \ + "lpa %%r0(%%sr3,%1),%0" \ + : "=r" (pa) \ + : "r" (va) \ + : "memory" \ + ); \ + pa; \ +}) + #define mfctl(reg) ({ \ unsigned long cr; \ __asm__ __volatile__( \ |