Fix places where using %gs changes the usermode ABI. There are a few places where the change in struct pt_regs and the use of %gs affect the userspace ABI. These are primarily debugging interfaces where thread state can be inspected or extracted. Signed-off-by: Jeremy Fitzhardinge Cc: Chuck Ebbert <76306.1226@compuserve.com> Cc: Zachary Amsden Cc: Jan Beulich Cc: Andi Kleen --- arch/i386/kernel/process.c | 6 +++--- arch/i386/kernel/ptrace.c | 18 ++++++------------ include/asm-i386/elf.h | 2 +- include/asm-i386/unwind.h | 1 + 4 files changed, 11 insertions(+), 16 deletions(-) =================================================================== --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -309,8 +309,8 @@ void show_regs(struct pt_regs * regs) regs->eax,regs->ebx,regs->ecx,regs->edx); printk("ESI: %08lx EDI: %08lx EBP: %08lx", regs->esi, regs->edi, regs->ebp); - printk(" DS: %04x ES: %04x\n", - 0xffff & regs->xds,0xffff & regs->xes); + printk(" DS: %04x ES: %04x GS: %04x\n", + 0xffff & regs->xds,0xffff & regs->xes, 0xffff & regs->xgs); cr0 = read_cr0(); cr2 = read_cr2(); @@ -504,7 +504,7 @@ void dump_thread(struct pt_regs * regs, dump->regs.ds = regs->xds; dump->regs.es = regs->xes; savesegment(fs,dump->regs.fs); - savesegment(gs,dump->regs.gs); + dump->regs.gs = regs->xgs; dump->regs.orig_eax = regs->orig_eax; dump->regs.eip = regs->eip; dump->regs.cs = regs->xcs; =================================================================== --- a/arch/i386/kernel/ptrace.c +++ b/arch/i386/kernel/ptrace.c @@ -94,13 +94,9 @@ static int putreg(struct task_struct *ch return -EIO; child->thread.fs = value; return 0; - case GS: - if (value && (value & 3) != 3) - return -EIO; - child->thread.gs = value; - return 0; case DS: case ES: + case GS: if (value && (value & 3) != 3) return -EIO; value &= 0xffff; @@ -116,8 +112,8 @@ static int putreg(struct task_struct *ch value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK; break; } - if (regno > GS*4) - regno -= 2*4; + if (regno > ES*4) + regno -= 1*4; put_stack_long(child, regno - sizeof(struct pt_regs), value); return 0; } @@ -131,18 +127,16 @@ static unsigned long getreg(struct task_ case FS: retval = child->thread.fs; break; - case GS: - retval = child->thread.gs; - break; case DS: case ES: + case GS: case SS: case CS: retval = 0xffff; /* fall through */ default: - if (regno > GS*4) - regno -= 2*4; + if (regno > ES*4) + regno -= 1*4; regno = regno - sizeof(struct pt_regs); retval &= get_stack_long(child, regno); } =================================================================== --- a/include/asm-i386/elf.h +++ b/include/asm-i386/elf.h @@ -88,7 +88,7 @@ typedef struct user_fxsr_struct elf_fpxr pr_reg[7] = regs->xds; \ pr_reg[8] = regs->xes; \ savesegment(fs,pr_reg[9]); \ - savesegment(gs,pr_reg[10]); \ + pr_reg[10] = regs->xgs; \ pr_reg[11] = regs->orig_eax; \ pr_reg[12] = regs->eip; \ pr_reg[13] = regs->xcs; \ =================================================================== --- a/include/asm-i386/unwind.h +++ b/include/asm-i386/unwind.h @@ -64,6 +64,7 @@ static inline void arch_unw_init_blocked info->regs.xss = __KERNEL_DS; info->regs.xds = __USER_DS; info->regs.xes = __USER_DS; + info->regs.xgs = __KERNEL_PDA; } extern asmlinkage int arch_unwind_init_running(struct unwind_frame_info *,