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author | Peter Maydell <peter.maydell@linaro.org> | 2020-02-18 11:24:57 +0000 |
---|---|---|
committer | Philippe Mathieu-Daudé <philmd@redhat.com> | 2020-02-20 14:47:08 +0100 |
commit | 19f703477314a5db09ffc3c0f6be9c45645f8302 (patch) | |
tree | 909e047c99a1abff54495692a085d9358cf1ebf6 /scripts/coccinelle/exec_rw_const.cocci | |
parent | 1ccda935d4fcc82a4371dc23d660197b0a6b6951 (diff) |
Avoid address_space_rw() with a constant is_write argument
The address_space_rw() function allows either reads or writes
depending on the is_write argument passed to it; this is useful
when the direction of the access is determined programmatically
(as for instance when handling the KVM_EXIT_MMIO exit reason).
Under the hood it just calls either address_space_write() or
address_space_read_full().
We also use it a lot with a constant is_write argument, though,
which has two issues:
* when reading "address_space_rw(..., 1)" this is less
immediately clear to the reader as being a write than
"address_space_write(...)"
* calling address_space_rw() bypasses the optimization
in address_space_read() that fast-paths reads of a
fixed length
This commit was produced with the included Coccinelle script
scripts/coccinelle/exec_rw_const.cocci.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20200218112457.22712-1-peter.maydell@linaro.org>
[PMD: Update macvm_set_cr0() reported by Laurent Vivier]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Diffstat (limited to 'scripts/coccinelle/exec_rw_const.cocci')
-rw-r--r-- | scripts/coccinelle/exec_rw_const.cocci | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/scripts/coccinelle/exec_rw_const.cocci b/scripts/coccinelle/exec_rw_const.cocci index 493d79cd13..4f0e634b3c 100644 --- a/scripts/coccinelle/exec_rw_const.cocci +++ b/scripts/coccinelle/exec_rw_const.cocci @@ -35,6 +35,19 @@ expression E1, E2, E3, E4; + address_space_write(E1, E2, E3, V, E4) ) +// Avoid uses of address_space_rw() with a constant is_write argument. +@@ +expression E1, E2, E3, E4, E5; +symbol true, false; +@@ +( +- address_space_rw(E1, E2, E3, E4, E5, false) ++ address_space_read(E1, E2, E3, E4, E5) +| +- address_space_rw(E1, E2, E3, E4, E5, true) ++ address_space_write(E1, E2, E3, E4, E5) +) + // Remove useless cast @@ expression E1, E2, E3, E4, E5, E6; |