https://bugs.kde.org/show_bug.cgi?id=497861
Bug ID: 497861
Summary: ARM: SUBW Rd, Rn, #uimm12 should accept SP as Rn
Classification: Developer tools
Product: valgrind
Version: 3.24 GIT
Platform: unspecified
OS: Other
Status: REPORTED
Severity: normal
Priority: NOR
Component: vex
Assignee: jsew...@acm.org
Reporter: aoikonomopou...@igalia.com
Target Milestone: ---
Created attachment 176865
--> https://bugs.kde.org/attachment.cgi?id=176865&action=edit
A trivial fix.
SUMMARY
The ARM manual specifies
(https://developer.arm.com/documentation/dui0489/i/arm-and-thumb-instructions/sub)
that SUBW Rd, Rn, #uimm12 accepts SP as Rn. However, the (T4) SUBW Rd, Rn,
#uimm12 case in guest_arm_toIR.c only accepts this form when SP is both Rd and
Rn.
STEPS TO REPRODUCE
1. Manually code up a program that uses such an instruction, e.g. I ran into
subw r3, sp, #8 in WebKit's JavaScriptCore.
2. Run the program natively, observe that it doesn't hit a SIGILL.
3. Run the program under valgrind, observe that it takes a SIGILL.
OBSERVED RESULT
SIGILL.
EXPECTED RESULT
No SIGILL.
SOFTWARE/OS VERSIONS
Valgrind at commit 04edd792bd707bace8ccbf947b48b0c70b7dc5d0.
ADDITIONAL INFORMATION
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