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amd64: Cleanups to setting TLS registers for Linux binaries.

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- Use update_pcb_bases() when updating FS or GS base addresses to
  permit use of FSBASE and GSBASE in Linux processes.  This also sets
  PCB_FULL_IRET.  linux32 was setting PCB_32BIT which should be a
  no-op (exec sets it).

- Remove write-only variables to construct unused segment descriptors
  for linux32.

Reviewed by:	kib
MFC after:	1 week
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D29026
This commit is contained in:
John Baldwin 2021-03-12 09:47:31 -08:00
parent 9221145868
commit 704547ce1c
2 changed files with 5 additions and 21 deletions
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5
sys/amd64/linux/linux_machdep.c
View File

@ -251,7 +251,7 @@ linux_arch_prctl(struct thread *td, struct linux_arch_prctl_args *args)
switch (args->code) {
case LINUX_ARCH_SET_GS:
if (args->addr < VM_MAXUSER_ADDRESS) {
set_pcb_flags(pcb, PCB_FULL_IRET);
update_pcb_bases(pcb);
pcb->pcb_gsbase = args->addr;
td->td_frame->tf_gs = _ugssel;
error = 0;
@ -260,7 +260,7 @@ linux_arch_prctl(struct thread *td, struct linux_arch_prctl_args *args)
break;
case LINUX_ARCH_SET_FS:
if (args->addr < VM_MAXUSER_ADDRESS) {
set_pcb_flags(pcb, PCB_FULL_IRET);
update_pcb_bases(pcb);
pcb->pcb_fsbase = args->addr;
td->td_frame->tf_fs = _ufssel;
error = 0;
@ -290,6 +290,7 @@ linux_set_cloned_tls(struct thread *td, void *desc)
return (EPERM);
pcb = td->td_pcb;
update_pcb_bases(pcb);
pcb->pcb_fsbase = (register_t)desc;
td->td_frame->tf_fs = _ufssel;

21
sys/amd64/linux32/linux32_machdep.c
View File

@ -394,11 +394,9 @@ linux_old_select(struct thread *td, struct linux_old_select_args *args)
int
linux_set_cloned_tls(struct thread *td, void *desc)
{
struct user_segment_descriptor sd;
struct l_user_desc info;
struct pcb *pcb;
int error;
int a[2];
error = copyin(desc, &info, sizeof(struct l_user_desc));
if (error) {
@ -410,14 +408,10 @@ linux_set_cloned_tls(struct thread *td, void *desc)
if (error)
linux_msg(td, "set_cloned_tls copyout info failed!");
a[0] = LINUX_LDT_entry_a(&info);
a[1] = LINUX_LDT_entry_b(&info);
memcpy(&sd, &a, sizeof(a));
pcb = td->td_pcb;
update_pcb_bases(pcb);
pcb->pcb_gsbase = (register_t)info.base_addr;
td->td_frame->tf_gs = GSEL(GUGS32_SEL, SEL_UPL);
set_pcb_flags(pcb, PCB_32BIT);
}
return (error);
@ -668,9 +662,7 @@ linux_set_thread_area(struct thread *td,
struct linux_set_thread_area_args *args)
{
struct l_user_desc info;
struct user_segment_descriptor sd;
struct pcb *pcb;
int a[2];
int error;
error = copyin(args->desc, &info, sizeof(struct l_user_desc));
@ -721,18 +713,9 @@ linux_set_thread_area(struct thread *td,
if (error)
return (error);
if (LINUX_LDT_empty(&info)) {
a[0] = 0;
a[1] = 0;
} else {
a[0] = LINUX_LDT_entry_a(&info);
a[1] = LINUX_LDT_entry_b(&info);
}
memcpy(&sd, &a, sizeof(a));
pcb = td->td_pcb;
update_pcb_bases(pcb);
pcb->pcb_gsbase = (register_t)info.base_addr;
set_pcb_flags(pcb, PCB_32BIT);
update_gdt_gsbase(td, info.base_addr);
return (0);