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? > > Al? > > Thanks, > Laurent >
