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[PULL 10/15] target/arm/arm-semi: fix SYS_OPEN to return nonzero filehan
From: |
Peter Maydell |
Subject: |
[PULL 10/15] target/arm/arm-semi: fix SYS_OPEN to return nonzero filehandle |
Date: |
Fri, 17 Jan 2020 14:28:11 +0000 |
From: Masahiro Yamada <address@hidden>
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: address@hidden
Signed-off-by: Masahiro Yamada <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
Message-id: address@hidden
Signed-off-by: Peter Maydell <address@hidden>
---
target/arm/arm-semi.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/target/arm/arm-semi.c b/target/arm/arm-semi.c
index 47d61f6fe1f..788fe61b51a 100644
--- a/target/arm/arm-semi.c
+++ b/target/arm/arm-semi.c
@@ -144,7 +144,8 @@ static int alloc_guestfd(void)
guestfd_array = g_array_new(FALSE, TRUE, sizeof(GuestFD));
}
- for (i = 0; i < guestfd_array->len; i++) {
+ /* SYS_OPEN should return nonzero handle on success. Start guestfd from 1
*/
+ for (i = 1; i < guestfd_array->len; i++) {
GuestFD *gf = &g_array_index(guestfd_array, GuestFD, i);
if (gf->type == GuestFDUnused) {
@@ -168,7 +169,7 @@ static GuestFD *do_get_guestfd(int guestfd)
return NULL;
}
- if (guestfd < 0 || guestfd >= guestfd_array->len) {
+ if (guestfd <= 0 || guestfd >= guestfd_array->len) {
return NULL;
}
--
2.20.1
- [PULL 00/15] target-arm queue, Peter Maydell, 2020/01/17
- [PULL 01/15] hw/misc: Add the STM32F4xx Sysconfig device, Peter Maydell, 2020/01/17
- [PULL 02/15] hw/misc: Add the STM32F4xx EXTI device, Peter Maydell, 2020/01/17
- [PULL 03/15] hw/arm: Add the STM32F4xx SoC, Peter Maydell, 2020/01/17
- [PULL 04/15] hw/arm: Add the Netduino Plus 2, Peter Maydell, 2020/01/17
- [PULL 05/15] tests/boot_linux_console: Add initrd test for the CubieBoard, Peter Maydell, 2020/01/17
- [PULL 08/15] hw/arm/allwinner-a10: Simplify by passing IRQs with qdev_pass_gpios(), Peter Maydell, 2020/01/17
- [PULL 07/15] hw/arm/allwinner-a10: Move SoC definitions out of header, Peter Maydell, 2020/01/17
- [PULL 06/15] tests/boot_linux_console: Add a SD card test for the CubieBoard, Peter Maydell, 2020/01/17
- [PULL 09/15] hw/arm/allwinner-a10: Remove local qemu_irq variables, Peter Maydell, 2020/01/17
- [PULL 10/15] target/arm/arm-semi: fix SYS_OPEN to return nonzero filehandle,
Peter Maydell <=
- [PULL 12/15] target/arm: adjust program counter for wfi exception in AArch32, Peter Maydell, 2020/01/17
- [PULL 11/15] i.MX: add an emulation for RNGC, Peter Maydell, 2020/01/17
- [PULL 14/15] target/arm: Return correct IL bit in merge_syn_data_abort, Peter Maydell, 2020/01/17
- [PULL 15/15] target/arm: Set ISSIs16Bit in make_issinfo, Peter Maydell, 2020/01/17
- [PULL 13/15] arm/gicv3: update virtual irq state after IAR register read, Peter Maydell, 2020/01/17
- Re: [PULL 00/15] target-arm queue, Peter Maydell, 2020/01/17