Le 16/01/2020 à 09:17, YunQiang Su a écrit : > Laurent Vivier <laurent@xxxxxxxxx> 于2020年1月16日周四 下午4:07写道： >> >> Le 16/01/2020 à 03:20, YunQiang Su a écrit : >>> From: YunQiang Su <ysu@xxxxxxxxxxxx> >>> >>> Currently program invoked by binfmt_misc cannot be aware about whether >>> P flag, aka preserve path is enabled. >>> >>> Some applications like qemu need to know since it has 2 use case: >>> 1. call by hand, like: qemu-mipsel-static test.app OPTION >>> so, qemu have to assume that P option is not enabled. >>> 2. call by binfmt_misc. If qemu cannot know about whether P flag is >>> enabled, distribution's have to set qemu without P flag, and >>> binfmt_misc call qemu like: >>> qemu-mipsel-static /absolute/path/to/test.app OPTION >>> even test.app is not called by absoulute path, like >>> ./relative/path/to/test.app >>> >>> This patch passes this information by the 3rd bits of unused AT_FLAGS. >>> Then, in qemu, we can get this info by: >>> getauxval(AT_FLAGS) & (1<<3) >>> >>> v1->v2: >>> not enable kdebug >>> >>> See: https://bugs.launchpad.net/qemu/+bug/1818483 >>> Signed-off-by: YunQiang Su <ysu@xxxxxxxxxxxx> >>> --- >>> fs/binfmt_elf.c | 6 +++++- >>> fs/binfmt_elf_fdpic.c | 6 +++++- >>> fs/binfmt_misc.c | 2 ++ >>> include/linux/binfmts.h | 4 ++++ >>> 4 files changed, 16 insertions(+), 2 deletions(-) >>> >>> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c >>> index f4713ea76e82..d33ee07d7f57 100644 >>> --- a/fs/binfmt_elf.c >>> +++ b/fs/binfmt_elf.c >>> @@ -178,6 +178,7 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, >>> unsigned char k_rand_bytes[16]; >>> int items; >>> elf_addr_t *elf_info; >>> + elf_addr_t flags = 0; >>> int ei_index; >>> const struct cred *cred = current_cred(); >>> struct vm_area_struct *vma; >>> @@ -252,7 +253,10 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, >>> NEW_AUX_ENT(AT_PHENT, sizeof(struct elf_phdr)); >>> NEW_AUX_ENT(AT_PHNUM, exec->e_phnum); >>> NEW_AUX_ENT(AT_BASE, interp_load_addr); >>> - NEW_AUX_ENT(AT_FLAGS, 0); >>> + if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0) { >>> + flags |= BINPRM_FLAGS_PRESERVE_ARGV0; >>> + } >> >> Perhaps we also need a different flag in AT_FLAG than in interp_flag as >> BINPRM_FLAGS_PRESERVE_ARGV0 is also part of the internal ABI? > > yep. It may be really a problem. > So, should we define a set of new macros for AT_FLAGS? Yes, I think. Thanks, Laurent
