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linux-user/mips: sync k0 TLS for EF_MIPS_MACH_OCTEON userlands

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Cavium Octeon userspace is not following a generic MIPS Linux TLS
ABI rule here. Older Octeon glibc uses the k0 register as the fast
thread pointer, while newer Octeon2 and Octeon3 glibc variants use
the normal rdhwr $29 path.

linux-user already updates CP0_UserLocal for cpu_set_tls() and
TARGET_NR_set_thread_area, but it does not keep gpr[26]
synchronized. That leaves EF_MIPS_MACH_OCTEON userlands able to
complete set_thread_area() and still reach pthread startup or
pthread_self() with a stale k0 value.

Use the existing MIPS ELF machine flags from linux-user/elfload.c and
mirror CP0_UserLocal into gpr[26] only for EF_MIPS_MACH_OCTEON.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
James Hilliard
2026-04-09 20:00:12 -06:00
committed by Helge Deller
parent 1730e6f33f
commit 4c681ba3b8
4 changed files with 10 additions and 1 deletions
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3
linux-user/elfload.c
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@@ -1476,6 +1476,9 @@ static void load_elf_image(const char *image_name, const ImageSource *src,
/* Usual start for brk is after all sections of the main executable. */
info->brk = TARGET_PAGE_ALIGN(hiaddr + load_bias);
info->elf_flags = ehdr->e_flags;
#ifdef TARGET_MIPS
info->use_k0_tls = (ehdr->e_flags & EF_MIPS_MACH) == EF_MIPS_MACH_OCTEON;
#endif
prot_exec = PROT_EXEC;
#ifdef TARGET_AARCH64

5
linux-user/mips/target_cpu.h
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@@ -35,7 +35,12 @@ static inline void cpu_clone_regs_parent(CPUMIPSState *env, unsigned flags)
static inline void cpu_set_tls(CPUMIPSState *env, target_ulong newtls)
{
TaskState *ts = get_task_state(env_cpu(env));
env->active_tc.CP0_UserLocal = newtls;
if (ts->info->use_k0_tls) {
env->active_tc.gpr[26] = newtls;
}
}
static inline abi_ulong get_sp_from_cpustate(CPUMIPSState *state)

1
linux-user/qemu.h
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@@ -65,6 +65,7 @@ struct image_info {
uint32_t note_flags;
#ifdef TARGET_MIPS
bool use_k0_tls;
int fp_abi;
int interp_fp_abi;
#endif

2
linux-user/syscall.c
View File

@@ -13216,7 +13216,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
#ifdef TARGET_NR_set_thread_area
case TARGET_NR_set_thread_area:
#if defined(TARGET_MIPS)
cpu_env->active_tc.CP0_UserLocal = arg1;
cpu_set_tls(cpu_env, arg1);
return 0;
#elif defined(TARGET_I386) && defined(TARGET_ABI32)
return do_set_thread_area(cpu_env, arg1);