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package/qemu: Fix a regression in semihosting

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The Buildroot's gitlab testing infra reported a build issue
with the qemu_arm_vexpress_tz_defconfig due to host-python3
modules issues [1]. Thoses issues has been fixed by the
previous patch.

But the defconfig doesn't boot with the current master
(2020.02-rc3).

It turn out that is an Qemu 4.2.0 regression that was
fixed upstream by [2]. This issue was found by using
git bisect old/new.

Fixes:
$ ../host/bin/qemu-system-arm -machine virt -machine secure=on -cpu cortex-a15 -smp 1 -s -m 1024 -d unimp -serial stdio -netdev user,id=vmnic -device virtio-net-device,netdev=vmnic -semihosting-config enable,target=native -bios bl1.bin
NOTICE:  Booting Trusted Firmware
NOTICE:  BL1: v2.0(release):2020.02-rc3-43-g9abf171ea6
NOTICE:  BL1: Built : 12:44:52, Mar  8 2020
ERROR:   Failed to load BL2 firmware.

After fixing host-python3 issue from [1]

[1] https://gitlab.com/buildroot.org/buildroot/-/jobs/456818689
[2] 21bf9b06cb

Signed-off-by: Adrien Grassein <adrien.grassein@smile.fr>
[Romain:
  - improve commit log
  - add upstream link
]
Signed-off-by: Romain Naour <romain.naour@smile.fr>
Cc: Etienne Carriere <etienne.carriere@linaro.org>
Cc: Gerome Burlats <gerome.burlats@smile.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
This commit is contained in:
Adrien Grassein 2020-03-08 19:35:35 +01:00 committed by Peter Korsgaard
parent 876e1b3479
commit c2cdde4887
1 changed files with 78 additions and 0 deletions
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78
package/qemu/4.2.0/0003-target-arm-arm-semi-fix-SYS_OPEN-to-return-nonzero-f.patch Normal file
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@ -0,0 +1,78 @@
From 318f83f387678a3c0a2a729b506613011c6830b2 Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <masahiroy@kernel.org>
Date: Fri, 17 Jan 2020 14:09:30 +0000
Subject: [PATCH] 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>
(cherry picked from commit 21bf9b06cb6d07c6cc437dfd47b47b28c2bb79db)
Signed-off-by: Adrien Grassein <adrien.grassein@smile.fr>
Signed-off-by: Romain Naour <romain.naour@smile.fr>
---
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 6f7b6d801b..4275dfc345 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;
}
--
2.24.1