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charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: AEF4C1C0005 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: edxoqocs8gasthjnb5dftm5e1m1rjj83 X-HE-Tag: 1680532810-968017 X-HE-Meta: U2FsdGVkX19xLsMH8wTrEIIgyIabvpmGU7/fnv6oP32lYOSA4lV0/fooq38ui0UnTvzSM2DYD/YbSi6LAjsPQ52Roh4Qt4ymvjo+yBsHtJTPrfVYfwEp5SW15AxlLY/ZVhuVWX2uer/EelC98Bw2YcC5n6AsLmxxYmUj5fZxK8Xm1TmMgVVCwSmtssYdy1JWyXyAKDo+Ue/H+/KuAQNfxVmefKZmQTa/CW+pFIBlu4LQ8tOHIqZKvKjKFSBT1+G7aZqaQG4BXxAevs2cXc7FA6VikpBbbA65a+cZGhxAeg0o/dRmlzOeGvAK7792uCu6yUolASBzRWnsGBf4uxqxdOu2Q+NzSDZ3RY1VoF4NnXMUOFSi7gIY+fTxiOJA8DFBfou5hu3MLZSXS248U/UY8xqTDn1vV+0Cg0DH78csirr9m0OjYeayJcxlYPXSvBrCKcJPCj97phW8sssRTG3xRpEOBbnryihE7OQcrj6+xKKSXQXKglVhlT7gKebFrcZAwWUSbogKPqsmJbz/qUmrhnVISA/msTI0D+UjFykqhiYBHddkpF6ECYWxmti4HTlyfLNlvJ6AP2ZxFIjnRTgyoW//EIJxTgnEBV9Kka/jlyESPZ2nSN6RZjEuJo5IdbLpKJ5bKFPiIhrYcmCeBRxWm5taB+qVieKuQF8+DF7WMuai+kXgx+B/Li2n1VgRIoOkyQQl5kTU9lue8ANJEAP43CK0ZMKERmfTeOgP0CY3rwiIDKegI+u+MlycYbMseY1+rmPBbdmy4n+gYS+rFGpctrpoJF23wbfmMAO7Akd7GAXb9ayAjeMDrgdULZBOsxsehG7FWMDi8KyrI9mzBST2gUL+xYaT0MzoqNjfffVyCX95G2wOvE7PKbMXXD6+tZbyRZHUK8glciGT8hTFnSqmDsXH238FM8yeIj5th+u1JGdmAdsEZTmNEfrWtGyByxQydiL42xwHHfj1UYEium4 h/ZfcIU9 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000278, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 2023=EB=85=84 4=EC=9B=94 3=EC=9D=BC (=EC=9B=94) =EC=98=A4=ED=9B=84 9:53, Pe= tr Mladek =EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1: > > On Mon 2023-04-03 19:46:17, Jaewon Kim wrote: > > Hello > > > > I've just changed %09lx to %09pK on my driver code to hide the address,= but I > > faced compiler error. The %9pK without 0 worked. > > What exactly do you want to achieve, please? Hello Thank you for your comment. I wanted to print phys_addr_t type value only when kptr_restrict sysctl is allowed. So I thought I could use %pK for that purpose. And the physical address is not that long. I wanted to make that length short like 9 hex. > > Note that printk() hashes pointers by default. It means that %p does not > print the value but a hash based on the value. > > If you print the same pointer twice, you will see the same hash, so > you know that the pointer is the same. But you do not see the address > so that you could not use the value for a security attack. > > See Documentation/core-api/printk-formats.rst > > Anyway, the main question if it makes sense to print the pointer value > at all. The address is not useful if it can't be compared with > other pointers or if the data on the address could not be checked. > > > Is there restriction on %pK which does now allow %0 ? I've wondered whe= ther I > > did wrong or it is a printk problem. > > > > To show easily I tried to add pr_info("%09pK\n", nodemask); in page_all= oc.c > > Then here's what I did. > > > > $ ARCH=3Dx86 make x86_64_defconfig ; make mm/page_alloc.o > > # > > # No change to .config > > # > > CALL scripts/checksyscalls.sh > > DESCEND objtool > > INSTALL libsubcmd_headers > > CC mm/page_alloc.o > > In file included from ./include/asm-generic/bug.h:22:0, > > from ./arch/x86/include/asm/bug.h:87, > > from ./include/linux/bug.h:5, > > from ./include/linux/mmdebug.h:5, > > from ./include/linux/mm.h:6, > > from mm/page_alloc.c:19: > > mm/page_alloc.c: In function =E2=80=98__alloc_pages=E2=80=99: > > ./include/linux/kern_levels.h:5:18: error: '0' flag used with =E2=80=98= %p=E2=80=99 gnu_printf format [-Werror=3Dformat=3D] > > #define KERN_SOH "\001" /* ASCII Start Of Header */ > > As Sergey already wrote. %p does not support any modification flags. Okay, then we can't use %09pK. I've just wondered because %9pK works. BR Jaewon Kim > > Best Regards, > Petr