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Cleanup SGX entry code #69040

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Merged
merged 3 commits into from
Feb 13, 2020
Merged

Cleanup SGX entry code #69040

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aeedc9d
Corrected ac_mitigation patch. That patch used the untrusted stack to…
raoulstrackx Feb 7, 2020
236ab6e
sanitize MXCSR/FPU control registers
raoulstrackx Feb 7, 2020
71b9ed4
Avoid jumping to Rust code with user %rsp (reentry_panic)
Feb 10, 2020
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11 changes: 11 additions & 0 deletions src/libstd/sys/sgx/abi/entry.S
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,14 @@ IMAGE_BASE:

/* We can store a bunch of data in the gap between MXCSR and the XSAVE header */

/* MXCSR initialization value for ABI */
.Lmxcsr_init:
.int 0x1f80

/* x87 FPU control word initialization value for ABI */
.Lfpucw_init:
.int 0x037f
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This is setting one of the reserved bits (6th) to 1?

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This is the default from the Intel SDM, Vol. 1, §8.1.5


/* The following symbols point at read-only data that will be filled in by the */
/* post-linker. */

Expand Down Expand Up @@ -173,6 +181,9 @@ sgx_entry:
mov %gs:tcsls_last_rsp,%r11
test %r11,%r11
jnz .Lusercall_ret
/* reset user state */
ldmxcsr .Lmxcsr_init(%rip)
fldcw .Lfpucw_init(%rip)
/* setup stack */
mov %gs:tcsls_tos,%rsp /* initially, RSP is not set to the correct value */
/* here. This is fixed below under "adjust stack". */
Expand Down