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| author | Josh Triplett <josh@joshtriplett.org> | 2023-04-04 14:31:48 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-04-19 01:29:53 +0200 |
| commit | ddc65971bb677aa9f6a4c21f76d3133e106f88eb (patch) | |
| tree | c369e01804784d9c749ebae87fad76eb29390c5b /include/uapi | |
| parent | maple_tree: simplify mas_wr_node_walk() (diff) | |
| download | linux-ddc65971bb677aa9f6a4c21f76d3133e106f88eb.tar.xz linux-ddc65971bb677aa9f6a4c21f76d3133e106f88eb.zip | |
prctl: add PR_GET_AUXV to copy auxv to userspace
If a library wants to get information from auxv (for instance,
AT_HWCAP/AT_HWCAP2), it has a few options, none of them perfectly reliable
or ideal:
- Be main or the pre-main startup code, and grub through the stack above
main. Doesn't work for a library.
- Call libc getauxval. Not ideal for libraries that are trying to be
libc-independent and/or don't otherwise require anything from other
libraries.
- Open and read /proc/self/auxv. Doesn't work for libraries that may run
in arbitrarily constrained environments that may not have /proc
mounted (e.g. libraries that might be used by an init program or a
container setup tool).
- Assume you're on the main thread and still on the original stack, and
try to walk the stack upwards, hoping to find auxv. Extremely bad
idea.
- Ask the caller to pass auxv in for you. Not ideal for a user-friendly
library, and then your caller may have the same problem.
Add a prctl that copies current->mm->saved_auxv to a userspace buffer.
Link: https://lkml.kernel.org/r/d81864a7f7f43bca6afa2a09fc2e850e4050ab42.1680611394.git.josh@joshtriplett.org
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/linux/prctl.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 1312a137f7fb..b99c0be72577 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -290,4 +290,6 @@ struct prctl_mm_map { #define PR_SET_VMA 0x53564d41 # define PR_SET_VMA_ANON_NAME 0 +#define PR_GET_AUXV 0x41555856 + #endif /* _LINUX_PRCTL_H */ |