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| author | Mikhail Maltsev <mikhail.maltsev@arm.com> | 2019-06-17 11:00:21 +0000 |
|---|---|---|
| committer | Mikhail Maltsev <mikhail.maltsev@arm.com> | 2019-06-17 11:00:21 +0000 |
| commit | d5323f6a707e376aab20ebe7864a78fc38fcedaa (patch) | |
| tree | 79dbbf6b3f86a160dccfea4a45e19b6882a2b4a2 | |
| parent | 2e46312ffd16982f0e991c9434d4908b107f5260 (diff) | |
| download | bcm5719-llvm-d5323f6a707e376aab20ebe7864a78fc38fcedaa.tar.gz bcm5719-llvm-d5323f6a707e376aab20ebe7864a78fc38fcedaa.zip | |
[libunwind][AArch64] Fix libunwind::Registers_arm64::jumpto
Summary:
The AArch64 version of the libunwind function which restores the
CPU state and resumes execution is not interrupt-safe. It restores
the target value of SP before loading the floating-point registers
from the context struct, but that struct is allocated on the stack
which is being deallocated. This means that if an interrupt occurs
during this function, and uses a lot of stack space, it could
overwrite the values about to be loaded into the floating-point
registers.
This patch fixes the issue.
Patch by Oliver Stannard.
Reviewers: phosek, chill
Reviewed By: chill
Subscribers: chill, javed.absar, kristof.beyls, christof, LukeCheeseman, pbarrio, olista01, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D63006
llvm-svn: 363545
| -rw-r--r-- | libunwind/src/UnwindRegistersRestore.S | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/libunwind/src/UnwindRegistersRestore.S b/libunwind/src/UnwindRegistersRestore.S index 01113565e8e..8122bf3e1b2 100644 --- a/libunwind/src/UnwindRegistersRestore.S +++ b/libunwind/src/UnwindRegistersRestore.S @@ -575,7 +575,8 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind15Registers_arm646jumptoEv) ldp x10,x11, [x0, #0x050] ldp x12,x13, [x0, #0x060] ldp x14,x15, [x0, #0x070] - ldp x16,x17, [x0, #0x080] + // x16 and x17 were clobbered by the call into the unwinder, so no point in + // restoring them. ldp x18,x19, [x0, #0x090] ldp x20,x21, [x0, #0x0A0] ldp x22,x23, [x0, #0x0B0] @@ -583,8 +584,6 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind15Registers_arm646jumptoEv) ldp x26,x27, [x0, #0x0D0] ldp x28,x29, [x0, #0x0E0] ldr x30, [x0, #0x100] // restore pc into lr - ldr x1, [x0, #0x0F8] - mov sp,x1 // restore sp ldp d0, d1, [x0, #0x110] ldp d2, d3, [x0, #0x120] @@ -604,7 +603,13 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind15Registers_arm646jumptoEv) ldr d30, [x0, #0x200] ldr d31, [x0, #0x208] + // Finally, restore sp. This must be done after the the last read from the + // context struct, because it is allocated on the stack, and an exception + // could clobber the de-allocated portion of the stack after sp has been + // restored. + ldr x16, [x0, #0x0F8] ldp x0, x1, [x0, #0x000] // restore x0,x1 + mov sp,x16 // restore sp ret x30 // jump to pc #elif defined(__arm__) && !defined(__APPLE__) |
