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authorPeter Maydell <peter.maydell@linaro.org>2020-02-18 11:24:57 +0000
committerPhilippe Mathieu-Daudé <philmd@redhat.com>2020-02-20 14:47:08 +0100
commit19f703477314a5db09ffc3c0f6be9c45645f8302 (patch)
tree909e047c99a1abff54495692a085d9358cf1ebf6 /scripts/coccinelle/exec_rw_const.cocci
parent1ccda935d4fcc82a4371dc23d660197b0a6b6951 (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.cocci13
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;