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| author | Roland McGrath <roland@hack.frob.com> | 2013-11-22 11:39:20 -0800 |
|---|---|---|
| committer | Roland McGrath <roland@hack.frob.com> | 2013-11-22 11:39:20 -0800 |
| commit | 068dcfd6758b2f50445d40cfe9d10e4284bd0635 (patch) | |
| tree | 998c08fbfd6f8aab2723c480ce3723785a541020 | |
| parent | 12e0e8c65d639fe1e648d116cb5caa434c34ab61 (diff) | |
| download | glibc-068dcfd6758b2f50445d40cfe9d10e4284bd0635.zip glibc-068dcfd6758b2f50445d40cfe9d10e4284bd0635.tar.gz glibc-068dcfd6758b2f50445d40cfe9d10e4284bd0635.tar.bz2 | |
ARM: Fix memcpy computed-jump calculations for ARM_ALWAYS_BX case.
| -rw-r--r-- | ports/ChangeLog.arm | 8 | ||||
| -rw-r--r-- | ports/sysdeps/arm/arm-features.h | 8 | ||||
| -rw-r--r-- | ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S | 21 |
3 files changed, 19 insertions, 18 deletions
diff --git a/ports/ChangeLog.arm b/ports/ChangeLog.arm index 0dfe5c7..2ee4444 100644 --- a/ports/ChangeLog.arm +++ b/ports/ChangeLog.arm @@ -1,3 +1,11 @@ +2013-11-22 Roland McGrath <roland@hack.frob.com> + + * sysdeps/arm/armv7/multiarch/memcpy_impl.S + [ARM_ALWAYS_BX] (dispatch_helper): Fix PC computation to properly + account for instructions after the reference to PC given that 'bx' + might actually be expanded to multiple instructions. + * sysdeps/arm/arm-features.h (ARM_BX_NINSNS): Macro removed. + 2013-10-30 Mike Frysinger <vapier@gentoo.org> * sysdeps/arm/configure.in: Moved to ... diff --git a/ports/sysdeps/arm/arm-features.h b/ports/sysdeps/arm/arm-features.h index 1d4b0f1..336b690 100644 --- a/ports/sysdeps/arm/arm-features.h +++ b/ports/sysdeps/arm/arm-features.h @@ -53,14 +53,6 @@ # define ARM_BX_ALIGN_LOG2 2 #endif -/* The number of instructions that 'bx' expands to. A more-specific - arm-features.h that defines 'bx' as a macro should define this to the - number instructions it expands to. This is used only in a context - where the 'bx' expansion won't cross an ARM_BX_ALIGN_LOG2 boundary. */ -#ifndef ARM_BX_NINSNS -# define ARM_BX_NINSNS 1 -#endif - /* An OS-specific arm-features.h file may define ARM_NO_INDEX_REGISTER to indicate that the two-register addressing modes must never be used. */ diff --git a/ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S b/ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S index ad43a3d..44cecb0 100644 --- a/ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S +++ b/ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S @@ -127,25 +127,26 @@ .purgem dispatch_step .endm #else -# if ARM_BX_ALIGN_LOG2 < 4 +# if ARM_BX_ALIGN_LOG2 < 3 # error case not handled # endif .macro dispatch_helper steps, log2_bytes_per_step - .p2align ARM_BX_ALIGN_LOG2 /* TMP1 gets (max_bytes - bytes_to_copy), where max_bytes is (STEPS << LOG2_BYTES_PER_STEP). - So this is (steps_to_skip << LOG2_BYTES_PER_STEP). */ - rsb tmp1, tmp1, #(\steps << \log2_bytes_per_step) - /* Pad so that the add;bx pair immediately precedes an alignment - boundary. Hence, TMP1=0 will run all the steps. */ - .rept (1 << (ARM_BX_ALIGN_LOG2 - 2)) - (2 + ARM_BX_NINSNS) - nop - .endr + So this is (steps_to_skip << LOG2_BYTES_PER_STEP). + Then it needs further adjustment to compensate for the + distance between the PC value taken below (0f + PC_OFS) + and the first step's instructions (1f). */ + rsb tmp1, tmp1, #((\steps << \log2_bytes_per_step) \ + + ((1f - PC_OFS - 0f) \ + >> (ARM_BX_ALIGN_LOG2 - \log2_bytes_per_step))) /* Shifting down LOG2_BYTES_PER_STEP gives us the number of steps to skip, then shifting up ARM_BX_ALIGN_LOG2 gives us the (byte) distance to add to the PC. */ - add tmp1, pc, tmp1, lsl #(ARM_BX_ALIGN_LOG2 - \log2_bytes_per_step) +0: add tmp1, pc, tmp1, lsl #(ARM_BX_ALIGN_LOG2 - \log2_bytes_per_step) bx tmp1 + .p2align ARM_BX_ALIGN_LOG2 +1: .endm .macro dispatch_7_dword |