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| author |   Rohan McLure <rmclure@linux.ibm.com> | 2022-09-21 16:55:51 +1000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2022-09-26 23:00:15 +1000 |
| commit | b6b1334c9510e162bd8ca0ae58403cafad9572f1 (patch) | |
| tree | ceea5be25758dd56fe846b0f8a4d80b5bd6d5c5a /tools/perf/arch/powerpc/entry/syscalls/syscall.tbl | |
| parent | powerpc: Use generic fallocate compatibility syscall (diff) | |
| download | linux-dev-b6b1334c9510e162bd8ca0ae58403cafad9572f1.tar.xz linux-dev-b6b1334c9510e162bd8ca0ae58403cafad9572f1.zip | |
powerpc/32: Remove powerpc select specialisation
Syscall #82 has been implemented for 32-bit platforms in a unique way on
powerpc systems. This hack will in effect guess whether the caller is
expecting new select semantics or old select semantics. It does so via a
guess, based off the first parameter. In new select, this parameter
represents the length of a user-memory array of file descriptors, and in
old select this is a pointer to an arguments structure.
The heuristic simply interprets sufficiently large values of its first
parameter as being a call to old select. The following is a discussion
on how this syscall should be handled.
As discussed in this thread, the existence of such a hack suggests that for
whatever powerpc binaries may predate glibc, it is most likely that they
would have taken use of the old select semantics. x86 and arm64 both
implement this syscall with oldselect semantics.
Remove the powerpc implementation, and update syscall.tbl to refer to emit
a reference to sys_old_select and compat_sys_old_select
for 32-bit binaries, in keeping with how other architectures support
syscall #82.
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/lkml/13737de5-0eb7-e881-9af0-163b0d29a1a0@csgroup.eu/
Link: https://lore.kernel.org/r/20220921065605.1051927-12-rmclure@linux.ibm.com
Diffstat (limited to 'tools/perf/arch/powerpc/entry/syscalls/syscall.tbl')
| -rw-r--r-- | tools/perf/arch/powerpc/entry/syscalls/syscall.tbl | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl index 2600b4237292..64f27cbbdd2c 100644 --- a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl +++ b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl @@ -110,7 +110,7 @@ 79 common settimeofday sys_settimeofday compat_sys_settimeofday 80 common getgroups sys_getgroups 81 common setgroups sys_setgroups -82 32 select ppc_select sys_ni_syscall +82 32 select sys_old_select compat_sys_old_select 82 64 select sys_ni_syscall 82 spu select sys_ni_syscall 83 common symlink sys_symlink |