54 lines
1.6 KiB
Diff
54 lines
1.6 KiB
Diff
From 5a52ee4b5cd152fa4ccd1c1f938ce2eba652af52 Mon Sep 17 00:00:00 2001
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From: Sergei Trofimovich <slyfox@gentoo.org>
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Date: Mon, 14 Dec 2015 23:59:17 +0000
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Subject: [PATCH] Add %esp to list of clobbered registers
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GCC assumes that it can combine stacks from
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outer
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grub_stage2()
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and inner
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trampoline doit()
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functions (optimisation -fcombine-stack-adjustments).
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But doit() function clobbers %esp in inline
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assebly statement as:
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asm volatile ("movl %%esp, %0\n\tmovl %1, %%esp\n"
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: "=&r" (realstack) : "r" (simstack));
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which tricks gcc into computing invalid local variable
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offsets from current %esp value.
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Fix by hinting gcc about %esp change in clobber list.
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Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
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---
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grub/asmstub.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/grub/asmstub.c b/grub/asmstub.c
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index 6354806..44b056f 100644
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--- a/grub/asmstub.c
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+++ b/grub/asmstub.c
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@@ -174,7 +174,7 @@ grub_stage2 (void)
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{
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/* Make sure our stack lives in the simulated memory area. */
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asm volatile ("movl %%esp, %0\n\tmovl %1, %%esp\n"
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- : "=&r" (realstack) : "r" (simstack));
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+ : "=&r" (realstack) : "r" (simstack) : "%esp");
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/* Do a setjmp here for the stop command. */
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if (! setjmp (env_for_exit))
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@@ -191,7 +191,7 @@ grub_stage2 (void)
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}
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/* Replace our stack before we use any local variables. */
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- asm volatile ("movl %0, %%esp\n" : : "r" (realstack));
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+ asm volatile ("movl %0, %%esp\n" : : "r" (realstack) : "%esp");
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}
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assert (grub_scratch_mem == 0);
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--
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2.6.3
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