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ARM: 9295/1: unwind:fix unwind abort for uleb128 case

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[ Upstream commit fa3eeb638de0c1a9d2d860e5b48259facdd65176 ]

When unwind instruction is 0xb2,the subsequent instructions
are uleb128 bytes.
For now,it uses only the first uleb128 byte in code.

For vsp increments of 0x204~0x400,use one uleb128 byte like below:
0xc06a00e4 <unwind_test_work>: 0x80b27fac
  Compact model index: 0
  0xb2 0x7f vsp = vsp + 1024
  0xac      pop {r4, r5, r6, r7, r8, r14}

For vsp increments larger than 0x400,use two uleb128 bytes like below:
0xc06a00e4 <unwind_test_work>: @0xc0cc9e0c
  Compact model index: 1
  0xb2 0x81 0x01 vsp = vsp + 1032
  0xac      pop {r4, r5, r6, r7, r8, r14}
The unwind works well since the decoded uleb128 byte is also 0x81.

For vsp increments larger than 0x600,use two uleb128 bytes like below:
0xc06a00e4 <unwind_test_work>: @0xc0cc9e0c
  Compact model index: 1
  0xb2 0x81 0x02 vsp = vsp + 1544
  0xac      pop {r4, r5, r6, r7, r8, r14}
In this case,the decoded uleb128 result is 0x101(vsp=0x204+(0x101<<2)).
While the uleb128 used in code is 0x81(vsp=0x204+(0x81<<2)).
The unwind aborts at this frame since it gets incorrect vsp.

To fix this,add uleb128 decode to cover all the above case.

Signed-off-by: Haibo Li <haibo.li@mediatek.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Haibo Li 2023-04-17 10:17:07 +01:00 committed by Greg Kroah-Hartman
parent 0433baa893
commit 6578e0f196
1 changed files with 24 additions and 1 deletions
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25
arch/arm/kernel/unwind.c
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@ -307,6 +307,29 @@ static int unwind_exec_pop_subset_r0_to_r3(struct unwind_ctrl_block *ctrl,
return URC_OK;
}
static unsigned long unwind_decode_uleb128(struct unwind_ctrl_block *ctrl)
{
unsigned long bytes = 0;
unsigned long insn;
unsigned long result = 0;
/*
* unwind_get_byte() will advance `ctrl` one instruction at a time, so
* loop until we get an instruction byte where bit 7 is not set.
*
* Note: This decodes a maximum of 4 bytes to output 28 bits data where
* max is 0xfffffff: that will cover a vsp increment of 1073742336, hence
* it is sufficient for unwinding the stack.
*/
do {
insn = unwind_get_byte(ctrl);
result |= (insn & 0x7f) << (bytes * 7);
bytes++;
} while (!!(insn & 0x80) && (bytes != sizeof(result)));
return result;
}
/*
* Execute the current unwind instruction.
*/
@ -360,7 +383,7 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
if (ret)
goto error;
} else if (insn == 0xb2) {
unsigned long uleb128 = unwind_get_byte(ctrl);
unsigned long uleb128 = unwind_decode_uleb128(ctrl);
ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
} else {