Hi Hari, From: "ext Kanigeri, Hari" <h-kanigeri2@xxxxxx> Subject: RE: [PATCH 2/2] DSPBRIDGE: add checking 128 byte alignment for dsp cache line size Date: Mon, 11 May 2009 17:09:03 +0200 > Hi Doyu-san, > > > A buffer shared with MPU and DSP has to be aligned on both cache line > > size to avoid memory corrupton with some DSP cache operations. Since > > there's no way for dspbridge to know how the shared buffer will be > > used like: "read-only", "write-only", "rw" through its life span, any > > shared buffer passed to DSP should be on this alignment. This patch > > adds checking those shared buffer alignement in bridgedriver cache > > operations and prevents userland applications from causing the above > > memory corruption. > > > > -- It looks like the buffer that are passed to the Bridge are not necessarily 128 byte aligned. > > This is the comment I received from Nikhil Mande (MM Engineer). > > [Nikhil Mande] "They are not necessarily "aligned" all the time. > Sometimes they just have 128 byte padding at the start & end of the buffer and the buffer pointer passed to bridge is not guaranteed to be 128 aligned. > So if you are adding such a check, it will require modifications OMX > components & test apps." The above means that passing unaligned address to dsp can cause memory corruption in kernel and this problem can be avoided only in the case where OMX(userland) is always supposed to pass aligned address. The above assumption cannot be accepted because kernel should always be robust against any incorrect behaviour of userland application. For example, even if an userland application passes any incorrect parameters to kernel through ioctl(), kernel shouldn't crash, but just returns -EINVAL. > > [Hari K] - Even with the above change, this might still be a hack for time being until the flushing of the user space buffers is moved from the Bridge driver to User-mode. > > > Thank you, > Best regards, > Hari > > > -----Original Message----- > > From: Hiroshi DOYU [mailto:Hiroshi.DOYU@xxxxxxxxx] > > Sent: Sunday, May 10, 2009 11:55 PM > > To: Kanigeri, Hari > > Cc: Menon, Nishanth; linux-omap@xxxxxxxxxxxxxxx; Hiroshi DOYU > > Subject: [PATCH 2/2] DSPBRIDGE: add checking 128 byte alignment for dsp > > cache line size > > > > From: Hiroshi DOYU <Hiroshi.DOYU@xxxxxxxxx> > > > > A buffer shared with MPU and DSP has to be aligned on both cache line > > size to avoid memory corrupton with some DSP cache operations. Since > > there's no way for dspbridge to know how the shared buffer will be > > used like: "read-only", "write-only", "rw" through its life span, any > > shared buffer passed to DSP should be on this alignment. This patch > > adds checking those shared buffer alignement in bridgedriver cache > > operations and prevents userland applications from causing the above > > memory corruption. > > > > Please refer to: > > https://omapzoom.org/gf/download/docmanfileversion/52/985/DSP_cache.pdf > > > > Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@xxxxxxxxx> > > --- > > drivers/dsp/bridge/rmgr/proc.c | 17 +++++++++++++++++ > > 1 files changed, 17 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/dsp/bridge/rmgr/proc.c > > b/drivers/dsp/bridge/rmgr/proc.c > > index 59073dd..437c3fe 100644 > > --- a/drivers/dsp/bridge/rmgr/proc.c > > +++ b/drivers/dsp/bridge/rmgr/proc.c > > @@ -159,6 +159,8 @@ > > #define PWR_TIMEOUT 500 /* Sleep/wake timout in msec */ > > #define EXTEND "_EXT_END" /* Extmem end addr in DSP binary */ > > > > +#define DSP_CACHE_SIZE 128 /* DSP cacheline size */ > > + > > extern char *iva_img; > > /* The PROC_OBJECT structure. */ > > struct PROC_OBJECT { > > @@ -722,6 +724,13 @@ DSP_STATUS PROC_FlushMemory(DSP_HPROCESSOR > > hProcessor, void *pMpuAddr, > > enum DSP_FLUSHTYPE FlushMemType = PROC_WRITEBACK_INVALIDATE_MEM; > > DBC_Require(cRefs > 0); > > > > + if (!IS_ALIGNED((u32)pMpuAddr, DSP_CACHE_SIZE) || > > + !IS_ALIGNED(ulSize, DSP_CACHE_SIZE)) { > > + pr_err("%s: Invalid alignment %p %x\n", > > + __func__, pMpuAddr, ulSize); > > + return DSP_EALIGNMENT; > > + } > > + > > GT_4trace(PROC_DebugMask, GT_ENTER, > > "Entered PROC_FlushMemory, args:\n\t" > > "hProcessor: 0x%x pMpuAddr: 0x%x ulSize 0x%x, ulFlags > > 0x%x\n", > > @@ -753,6 +762,14 @@ DSP_STATUS PROC_InvalidateMemory(DSP_HPROCESSOR > > hProcessor, void *pMpuAddr, > > "Entered PROC_InvalidateMemory, args:\n\t" > > "hProcessor: 0x%x pMpuAddr: 0x%x ulSize 0x%x\n", hProcessor, > > pMpuAddr, ulSize); > > + > > + if (!IS_ALIGNED((u32)pMpuAddr, DSP_CACHE_SIZE) || > > + !IS_ALIGNED(ulSize, DSP_CACHE_SIZE)) { > > + pr_err("%s: Invalid alignment %p %x\n", > > + __func__, pMpuAddr, ulSize); > > + return DSP_EALIGNMENT; > > + } > > + > > (void)SYNC_EnterCS(hProcLock); > > MEM_FlushCache(pMpuAddr, ulSize, FlushMemType); > > (void)SYNC_LeaveCS(hProcLock); > > -- > > 1.6.0.4 > > > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
