| 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 |
| |