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22f975f4ff
Patch from Nikola Valerjev Single stepping an application using ptrace() fails over ARM instructions BX and BLX. Steps to reproduce: Compile and link the following files main.c ----- void foo(); int main() { foo(); return 0; } foo.s ----- .text .globl foo foo: BX LR Using ptrace() functionality, run to main(), and start singlestepping. Singlestep over \"BX LR\" instruction won\'t transfer the control back to main, but run the code to completion. This problems seems to be in the function get_branch_address() in arch/arm/kernel/ptrace.c. The function doesn\'t seem to recognize BX and BLX instructions as branches. BX and BLX instructions can be used to convert from ARM to Thumb mode if the target address has the low bit set. However, they are also perfectly legal in the ARM only mode. Although other things in the kernel seem to indicate that only ARM mode is accepted (and not Thumb), many compilers will generate BX and BLX instructions even when generating ARM only code. Signed-off-by: Nikola Valerjev <nikola@ghs.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> |
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