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| author | sukadev@linux.vnet.ibm.com <sukadev@linux.vnet.ibm.com> | 2011-12-02 12:26:23 +0000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2011-12-08 14:22:52 +1100 |
| commit | 8a3e3d31d13ece3003e8f750178a7db02c5cd123 (patch) | |
| tree | 975f02f4077cf9631de20011211fddb5367f937a /arch | |
| parent | 11eab297f57bd6168425ae968e56c314e71b024e (diff) | |
| download | lwn-8a3e3d31d13ece3003e8f750178a7db02c5cd123.tar.gz lwn-8a3e3d31d13ece3003e8f750178a7db02c5cd123.zip | |
powerpc: Punch a hole in /dev/mem for librtas
With CONFIG_STRICT_DEVMEM=y, user space cannot read any part of /dev/mem.
Since this breaks librtas, punch a hole in /dev/mem to allow access to the
rmo_buffer that librtas needs.
Anton Blanchard reported the problem and helped with the fix.
A quick test for this patch:
# cat /proc/rtas/rmo_buffer
000000000f190000 10000
# python -c "print 0x000000000f190000 / 0x10000"
3865
# dd if=/dev/mem of=/tmp/foo count=1 bs=64k skip=3865
1+0 records in
1+0 records out
65536 bytes (66 kB) copied, 0.000205235 s, 319 MB/s
# dd if=/dev/mem of=/tmp/foo
dd: reading `/dev/mem': Operation not permitted
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.00022519 s, 0.0 kB/s
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/include/asm/rtas.h | 12 | ||||
| -rw-r--r-- | arch/powerpc/mm/mem.c | 3 |
2 files changed, 15 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h index 1646b76bd3d2..01c143bb77ae 100644 --- a/arch/powerpc/include/asm/rtas.h +++ b/arch/powerpc/include/asm/rtas.h @@ -313,5 +313,17 @@ static inline u32 rtas_config_addr(int busno, int devfn, int reg) extern void __cpuinit rtas_give_timebase(void); extern void __cpuinit rtas_take_timebase(void); +#ifdef CONFIG_PPC_RTAS +static inline int page_is_rtas_user_buf(unsigned long pfn) +{ + unsigned long paddr = (pfn << PAGE_SHIFT); + if (paddr >= rtas_rmo_buf && paddr < (rtas_rmo_buf + RTAS_RMOBUF_MAX)) + return 1; + return 0; +} +#else +static inline int page_is_rtas_user_buf(unsigned long pfn) { return 0;} +#endif + #endif /* __KERNEL__ */ #endif /* _POWERPC_RTAS_H */ diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 83d819f30864..395f42d5f785 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -51,6 +51,7 @@ #include <asm/vdso.h> #include <asm/fixmap.h> #include <asm/swiotlb.h> +#include <asm/rtas.h> #include "mmu_decl.h" @@ -600,6 +601,8 @@ int devmem_is_allowed(unsigned long pfn) return 0; if (!page_is_ram(pfn)) return 1; + if (page_is_rtas_user_buf(pfn)) + return 1; return 0; } #endif /* CONFIG_STRICT_DEVMEM */ |