51 lines
2.2 KiB
Text
51 lines
2.2 KiB
Text
From: jan.kiszka@siemens.com (Jan Kiszka)
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Subject: [Qemu-devel] [PATCH 1/5] kqemu: x86-64: Run 16-bit-stack-return in
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ring 0
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Date: Fri, 29 May 2009 19:18:31 +0200
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Message-ID: <20090529171831.14265.89986.stgit@mchn012c.ww002.siemens.net>
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To: qemu-devel@nongnu.org
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The fix-up code for returning to 16 bit stack segments is currently
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executed in ring 1. This has the side effect that the interrupt flag
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remains cleared on return from ring 1 to the guest's ring 3 as its
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IOPL is 0 (ie. iret can only modify IF when run in ring 0).
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Fix this by moving the 32 bit return trampoline into ring 0.
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Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
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---
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common/kernel.c | 8 ++++----
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1 files changed, 4 insertions(+), 4 deletions(-)
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diff --git common/kernel.c common/kernel.c
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index 6a88452..1d7a69e 100644
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Index: common/kernel.c
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--- common/kernel.c
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+++ common/kernel.c
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@@ -422,8 +422,8 @@ struct kqemu_state *kqemu_init(struct kqemu_init *d,
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#ifdef __x86_64__
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s->monitor_ds_sel = 0; /* no need for a specific data segment */
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/* used for 16 bit esp fix */
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- s->monitor_cs32_sel = (s->monitor_selector_base + (7 << 3)) | 1;
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- s->monitor_ss16_sel = (s->monitor_selector_base + (6 << 3)) | 1;
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+ s->monitor_cs32_sel = s->monitor_selector_base + (7 << 3);
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+ s->monitor_ss16_sel = s->monitor_selector_base + (6 << 3);
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s->monitor_ss_null_sel = (s->monitor_selector_base + (1 << 3)) | 3;
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#else
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s->monitor_ds_sel = s->monitor_selector_base + (1 << 3);
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@@ -495,9 +495,9 @@ struct kqemu_state *kqemu_init(struct kqemu_init *d,
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0, 0xfffff, 0xa09a); /* long mode segment */
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set_seg((uint32_t *)(dt_table + (s->monitor_ss16_sel >> 3)),
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(s->monitor_data_vaddr + offsetof(struct kqemu_state, stack)) & ~0xffff,
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- 0xffff, 0x00b2); /* SS16 segment for 16 bit ESP fix */
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+ 0xffff, 0x0092); /* SS16 segment for 16 bit ESP fix */
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set_seg((uint32_t *)(dt_table + (s->monitor_cs32_sel >> 3)),
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- 0, 0xfffff, 0xc0ba); /* CS32 segment for 16 bit ESP fix */
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+ 0, 0xfffff, 0xc09a); /* CS32 segment for 16 bit ESP fix */
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set_seg((uint32_t *)(dt_table + (s->monitor_ss_null_sel >> 3)),
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0, 0, 0x40f2); /* substitute for null SS segment */
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#else
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