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authorMichael Ellerman2018-07-10 16:20:56 +1000
committerMichael Ellerman2018-08-10 22:26:10 +1000
commitf7a6947cd49b7ff4e03f1b4f7e7b223003d752ca (patch)
tree86107043996f10e9a662cea876f1b54c47354c6d /mm/hugetlb.c
parentf405b510c93eeb7390d0e2c6ef8d12af9a33021a (diff)
powerpc/uaccess: Enable get_user(u64, *p) on 32-bit
Currently if you build a 32-bit powerpc kernel and use get_user() to load a u64 value it will fail to build with eg: kernel/rseq.o: In function `rseq_get_rseq_cs': kernel/rseq.c:123: undefined reference to `__get_user_bad' This is hitting the check in __get_user_size() that makes sure the size we're copying doesn't exceed the size of the destination: #define __get_user_size(x, ptr, size, retval) do { retval = 0; __chk_user_ptr(ptr); if (size > sizeof(x)) (x) = __get_user_bad(); Which doesn't immediately make sense because the size of the destination is u64, but it's not really, because __get_user_check() etc. internally create an unsigned long and copy into that: #define __get_user_check(x, ptr, size) ({ long __gu_err = -EFAULT; unsigned long __gu_val = 0; The problem being that on 32-bit unsigned long is not big enough to hold a u64. We can fix this with a trick from hpa in the x86 code, we statically check the type of x and set the type of __gu_val to either unsigned long or unsigned long long. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'mm/hugetlb.c')
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