e893286918
On gcc5 the kernel does not link:
ld: .eh_frame_hdr table[4] FDE at 0000000000000648 overlaps table[5] FDE at 0000000000000670.
Because prior GCC versions always emitted NOPs on ALIGN directives, but
gcc5 started omitting them.
.LSTARTFDEDLSI1 says:
/* HACK: The dwarf2 unwind routines will subtract 1 from the
return address to get an address in the middle of the
presumed call instruction. Since we didn't get here via
a call, we need to include the nop before the real start
to make up for it. */
.long .LSTART_sigreturn-1-. /* PC-relative start address */
But commit 69d0627a7f ("x86 vDSO: reorder vdso32 code") from 2.6.25
replaced .org __kernel_vsyscall+32,0x90 by ALIGN right before
__kernel_sigreturn.
Of course, ALIGN need not generate any NOP in there. Esp. gcc5 collapses
vclock_gettime.o and int80.o together with no generated NOPs as "ALIGN".
So fix this by adding to that point at least a single NOP and make the
function ALIGN possibly with more NOPs then.
Kudos for reporting and diagnosing should go to Richard.
Reported-by: Richard Biener <rguenther@suse.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: <stable@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1425543211-12542-1-git-send-email-jslaby@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
146 lines
5 KiB
ArmAsm
146 lines
5 KiB
ArmAsm
/*
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* Common code for the sigreturn entry points in vDSO images.
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* So far this code is the same for both int80 and sysenter versions.
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* This file is #include'd by int80.S et al to define them first thing.
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* The kernel assumes that the addresses of these routines are constant
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* for all vDSO implementations.
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*/
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#include <linux/linkage.h>
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#include <asm/unistd_32.h>
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#include <asm/asm-offsets.h>
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#ifndef SYSCALL_ENTER_KERNEL
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#define SYSCALL_ENTER_KERNEL int $0x80
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#endif
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.text
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.globl __kernel_sigreturn
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.type __kernel_sigreturn,@function
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nop /* this guy is needed for .LSTARTFDEDLSI1 below (watch for HACK) */
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ALIGN
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__kernel_sigreturn:
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.LSTART_sigreturn:
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popl %eax /* XXX does this mean it needs unwind info? */
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movl $__NR_sigreturn, %eax
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SYSCALL_ENTER_KERNEL
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.LEND_sigreturn:
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nop
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.size __kernel_sigreturn,.-.LSTART_sigreturn
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.globl __kernel_rt_sigreturn
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.type __kernel_rt_sigreturn,@function
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ALIGN
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__kernel_rt_sigreturn:
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.LSTART_rt_sigreturn:
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movl $__NR_rt_sigreturn, %eax
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SYSCALL_ENTER_KERNEL
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.LEND_rt_sigreturn:
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nop
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.size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
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.previous
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.section .eh_frame,"a",@progbits
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.LSTARTFRAMEDLSI1:
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.long .LENDCIEDLSI1-.LSTARTCIEDLSI1
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.LSTARTCIEDLSI1:
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.long 0 /* CIE ID */
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.byte 1 /* Version number */
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.string "zRS" /* NUL-terminated augmentation string */
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.uleb128 1 /* Code alignment factor */
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.sleb128 -4 /* Data alignment factor */
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.byte 8 /* Return address register column */
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.uleb128 1 /* Augmentation value length */
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.byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
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.byte 0 /* DW_CFA_nop */
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.align 4
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.LENDCIEDLSI1:
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.long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
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.LSTARTFDEDLSI1:
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.long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */
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/* HACK: The dwarf2 unwind routines will subtract 1 from the
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return address to get an address in the middle of the
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presumed call instruction. Since we didn't get here via
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a call, we need to include the nop before the real start
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to make up for it. */
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.long .LSTART_sigreturn-1-. /* PC-relative start address */
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.long .LEND_sigreturn-.LSTART_sigreturn+1
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.uleb128 0 /* Augmentation */
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/* What follows are the instructions for the table generation.
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We record the locations of each register saved. This is
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complicated by the fact that the "CFA" is always assumed to
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be the value of the stack pointer in the caller. This means
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that we must define the CFA of this body of code to be the
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saved value of the stack pointer in the sigcontext. Which
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also means that there is no fixed relation to the other
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saved registers, which means that we must use DW_CFA_expression
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to compute their addresses. It also means that when we
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adjust the stack with the popl, we have to do it all over again. */
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#define do_cfa_expr(offset) \
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.byte 0x0f; /* DW_CFA_def_cfa_expression */ \
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.uleb128 1f-0f; /* length */ \
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0: .byte 0x74; /* DW_OP_breg4 */ \
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.sleb128 offset; /* offset */ \
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.byte 0x06; /* DW_OP_deref */ \
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1:
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#define do_expr(regno, offset) \
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.byte 0x10; /* DW_CFA_expression */ \
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.uleb128 regno; /* regno */ \
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.uleb128 1f-0f; /* length */ \
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0: .byte 0x74; /* DW_OP_breg4 */ \
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.sleb128 offset; /* offset */ \
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1:
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do_cfa_expr(IA32_SIGCONTEXT_sp+4)
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do_expr(0, IA32_SIGCONTEXT_ax+4)
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do_expr(1, IA32_SIGCONTEXT_cx+4)
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do_expr(2, IA32_SIGCONTEXT_dx+4)
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do_expr(3, IA32_SIGCONTEXT_bx+4)
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do_expr(5, IA32_SIGCONTEXT_bp+4)
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do_expr(6, IA32_SIGCONTEXT_si+4)
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do_expr(7, IA32_SIGCONTEXT_di+4)
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do_expr(8, IA32_SIGCONTEXT_ip+4)
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.byte 0x42 /* DW_CFA_advance_loc 2 -- nop; popl eax. */
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do_cfa_expr(IA32_SIGCONTEXT_sp)
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do_expr(0, IA32_SIGCONTEXT_ax)
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do_expr(1, IA32_SIGCONTEXT_cx)
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do_expr(2, IA32_SIGCONTEXT_dx)
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do_expr(3, IA32_SIGCONTEXT_bx)
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do_expr(5, IA32_SIGCONTEXT_bp)
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do_expr(6, IA32_SIGCONTEXT_si)
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do_expr(7, IA32_SIGCONTEXT_di)
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do_expr(8, IA32_SIGCONTEXT_ip)
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.align 4
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.LENDFDEDLSI1:
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.long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
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.LSTARTFDEDLSI2:
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.long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */
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/* HACK: See above wrt unwind library assumptions. */
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.long .LSTART_rt_sigreturn-1-. /* PC-relative start address */
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.long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1
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.uleb128 0 /* Augmentation */
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/* What follows are the instructions for the table generation.
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We record the locations of each register saved. This is
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slightly less complicated than the above, since we don't
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modify the stack pointer in the process. */
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do_cfa_expr(IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_sp)
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do_expr(0, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ax)
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do_expr(1, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_cx)
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do_expr(2, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_dx)
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do_expr(3, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bx)
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do_expr(5, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bp)
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do_expr(6, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_si)
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do_expr(7, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_di)
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do_expr(8, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ip)
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.align 4
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.LENDFDEDLSI2:
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.previous
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