| Message ID | 1403618237-26248-2-git-send-email-Varun.Sethi@freescale.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Tue, Jun 24, 2014 at 07:27:15PM +0530, Varun Sethi wrote: > /* window size is 2^(WSE+1) bytes */ > - return __ffs(addrspace_size) - 1; > + return fls64(addrspace_size) - 2; This looks bogus, why do you replace ffs (find-first-bit) by fls (find-last-bit)? Joerg
> -----Original Message----- > From: Joerg Roedel [mailto:joro@8bytes.org] > Sent: Friday, July 04, 2014 4:15 PM > To: Sethi Varun-B16395 > Cc: iommu@lists.linux-foundation.org; linux-kernel@vger.kernel.org; > linuxppc-dev@lists.ozlabs.org; alex.williamson@redhat.com > Subject: Re: [PATCH 1/3] iommu/fsl: Fix PAMU window size check. > > On Tue, Jun 24, 2014 at 07:27:15PM +0530, Varun Sethi wrote: > > /* window size is 2^(WSE+1) bytes */ > > - return __ffs(addrspace_size) - 1; > > + return fls64(addrspace_size) - 2; > > This looks bogus, why do you replace ffs (find-first-bit) by fls (find- > last-bit)? > Address space size is always a power of 2. This change was required to handle address sizes > 32bit width on 32 bit architectures. -Varun
diff --git a/drivers/iommu/fsl_pamu.c b/drivers/iommu/fsl_pamu.c index b99dd88..bb446d7 100644 --- a/drivers/iommu/fsl_pamu.c +++ b/drivers/iommu/fsl_pamu.c @@ -170,10 +170,10 @@ int pamu_disable_liodn(int liodn) static unsigned int map_addrspace_size_to_wse(phys_addr_t addrspace_size) { /* Bug if not a power of 2 */ - BUG_ON(!is_power_of_2(addrspace_size)); + BUG_ON((addrspace_size & (addrspace_size - 1))); /* window size is 2^(WSE+1) bytes */ - return __ffs(addrspace_size) - 1; + return fls64(addrspace_size) - 2; } /* Derive the PAACE window count encoding for the subwindow count */ @@ -351,7 +351,7 @@ int pamu_config_ppaace(int liodn, phys_addr_t win_addr, phys_addr_t win_size, struct paace *ppaace; unsigned long fspi; - if (!is_power_of_2(win_size) || win_size < PAMU_PAGE_SIZE) { + if ((win_size & (win_size - 1)) || win_size < PAMU_PAGE_SIZE) { pr_debug("window size too small or not a power of two %llx\n", win_size); return -EINVAL; } @@ -464,7 +464,7 @@ int pamu_config_spaace(int liodn, u32 subwin_cnt, u32 subwin, return -ENOENT; } - if (!is_power_of_2(subwin_size) || subwin_size < PAMU_PAGE_SIZE) { + if ((subwin_size & (subwin_size - 1)) || subwin_size < PAMU_PAGE_SIZE) { pr_debug("subwindow size out of range, or not a power of 2\n"); return -EINVAL; } diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c index 93072ba..3dd0b8e 100644 --- a/drivers/iommu/fsl_pamu_domain.c +++ b/drivers/iommu/fsl_pamu_domain.c @@ -301,7 +301,7 @@ static int check_size(u64 size, dma_addr_t iova) * Size must be a power of two and at least be equal * to PAMU page size. */ - if (!is_power_of_2(size) || size < PAMU_PAGE_SIZE) { + if ((size & (size - 1)) || size < PAMU_PAGE_SIZE) { pr_debug("%s: size too small or not a power of two\n", __func__); return -EINVAL; }
is_power_of_2 requires an unsigned long parameter which would lead to truncation of 64 bit values on 32 bit architectures. __ffs also expects an unsigned long parameter thus won't work for 64 bit values on 32 bit architectures. Signed-off-by: Varun Sethi <Varun.Sethi@freescale.com> --- drivers/iommu/fsl_pamu.c | 8 ++++---- drivers/iommu/fsl_pamu_domain.c | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-)