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authorMasahiro Yamada <masahiroy@kernel.org>2020-01-17 14:09:30 +0000
committerPeter Maydell <peter.maydell@linaro.org>2020-01-17 14:09:30 +0000
commit21bf9b06cb6d07c6cc437dfd47b47b28c2bb79db (patch)
tree905a6779a38861191c7c60ac6aa5ffb6a779fbd8 /hw/arm/fsl-imx25.c
parentaf4ba4ed13b2bbfd2d33527741810a5905a11310 (diff)
target/arm/arm-semi: fix SYS_OPEN to return nonzero filehandle
According to the specification "Semihosting for AArch32 and Aarch64", the SYS_OPEN operation should return: - A nonzero handle if the call is successful - -1 if the call is not successful So, it should never return 0. Prior to commit 35e9a0a8ce4b ("target/arm/arm-semi: Make semihosting code hand out its own file descriptors"), the guest fd matched to the host fd. It returned a nonzero handle on success since the fd 0 is already used for stdin. Now that the guest fd is the index of guestfd_array, it starts from 0. I noticed this issue particularly because Trusted Firmware-A built with PLAT=qemu is no longer working. Its io_semihosting driver only handles a positive return value as a valid filehandle. Basically, there are two ways to fix this: - Use (guestfd - 1) as the index of guestfs_arrary. We need to insert increment/decrement to convert the guestfd and the array index back and forth. - Keep using guestfd as the index of guestfs_array. The first entry of guestfs_array is left unused. I thought the latter is simpler. We end up with wasting a small piece of memory for the unused first entry of guestfd_array, but this is probably not a big deal. Fixes: 35e9a0a8ce4b ("target/arm/arm-semi: Make semihosting code hand out its own file descriptors") Cc: qemu-stable@nongnu.org Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20200109041228.10131-1-masahiroy@kernel.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'hw/arm/fsl-imx25.c')
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