From 72d98d16ed09584660d0cbb759d90f8dfeef2343 Mon Sep 17 00:00:00 2001 From: Mickael Guene Date: Wed, 16 Dec 2015 10:09:05 +0100 Subject: [ARM] Add support for thumb1 pcrop relocations. To support thumb1 execute-only code we need to support four new relocations (R_ARM_THM_ALU_ABS_G0_NC, R_ARM_THM_ALU_ABS_G1_NC, R_ARM_THM_ALU_ABS_G2_NC and R_ARM_THM_ALU_ABS_G3_NC). These relocations allow the static linker to finalize construction of symbol address. Typical sequence of code to get address of the symbol foo is then the following : movs r3, #:upper8_15:#foo lsls r3, #8 adds r3, #:upper0_7:#foo lsls r3, #8 adds r3, #:lower8_15:#foo lsls r3, #8 adds r3, #:lower0_7:#foo This will give following sequence of text and relocations after assembly : 4: 2300 movs r3, #0 4: R_ARM_THM_ALU_ABS_G3_NC foo 6: 021b lsls r3, r3, #8 8: 3300 adds r3, #0 8: R_ARM_THM_ALU_ABS_G2_NC foo a: 021b lsls r3, r3, #8 c: 3300 adds r3, #0 c: R_ARM_THM_ALU_ABS_G1_NC foo e: 021b lsls r3, r3, #8 10: 3300 adds r3, #0 10: R_ARM_THM_ALU_ABS_G0_NC foo --- gas/doc/c-arm.texi | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'gas/doc') diff --git a/gas/doc/c-arm.texi b/gas/doc/c-arm.texi index ee26e6d..091fc93 100644 --- a/gas/doc/c-arm.texi +++ b/gas/doc/c-arm.texi @@ -537,6 +537,22 @@ respectively. For example to load the 32-bit address of foo into r0: MOVT r0, #:upper16:foo @end smallexample +Relocations @samp{R_ARM_THM_ALU_ABS_G0_NC}, @samp{R_ARM_THM_ALU_ABS_G1_NC}, +@samp{R_ARM_THM_ALU_ABS_G2_NC} and @samp{R_ARM_THM_ALU_ABS_G3_NC} can be +generated by prefixing the value with @samp{#:lower0_7:#}, +@samp{#:lower8_15:#}, @samp{#:upper0_7:#} and @samp{#:upper8_15:#} +respectively. For example to load the 32-bit address of foo into r0: + +@smallexample + MOVS r0, #:upper8_15:#foo + LSLS r0, r0, #8 + ADDS r0, #:upper0_7:#foo + LSLS r0, r0, #8 + ADDS r0, #:lower8_15:#foo + LSLS r0, r0, #8 + ADDS r0, #:lower0_7:#foo +@end smallexample + @node ARM-Neon-Alignment @subsection NEON Alignment Specifiers -- cgit v1.1