3rd-party/linux-kernel-module-cheat
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x86 asm: align stack to 16-bits for abort() call

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Fixes the failing tests that called abort(). For coincidence, only native
tests were failing.

Asked at: https://stackoverflow.com/questions/56324948/why-does-calling-the-c-abort-function-from-an-x86-64-assembly-function-lead-to
This commit is contained in:
Ciro Santilli 六四事件 法轮功
2019-05-27 00:00:03 +00:00
parent 48079d0843
commit 6e790042f0
2 changed files with 5 additions and 1 deletions
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4
README.adoc
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@@ -11998,6 +11998,8 @@ Examples:
* link:lkmc/x86_64.h[] `ENTRY` and `EXIT` * link:lkmc/x86_64.h[] `ENTRY` and `EXIT`
One important catch is that the stack must always be aligned to 16-bits before making calls: https://stackoverflow.com/questions/56324948/why-does-calling-the-c-abort-function-from-an-x86-64-assembly-function-lead-to
Bibliography: Bibliography:
* https://en.wikipedia.org/wiki/X86_calling_conventions#System_V_AMD64_ABI * https://en.wikipedia.org/wiki/X86_calling_conventions#System_V_AMD64_ABI
@@ -13434,7 +13436,7 @@ output:
.... ....
CPSR.M 0x3 CPSR.M 0x3
CPSR.M 0x3 CPSR.M 0xA
CPSR.M 0x3 CPSR.M 0x3
CurrentEL.EL 0x1 CurrentEL.EL 0x1
CurrentEL.EL 0x2 CurrentEL.EL 0x2

2
lkmc/x86_64.h
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@@ -31,6 +31,7 @@
* https://github.com/cirosantilli/linux-kernel-module-cheat#x86_64-calling-convention * https://github.com/cirosantilli/linux-kernel-module-cheat#x86_64-calling-convention
*/ */
#define LKMC_EPILOGUE \ #define LKMC_EPILOGUE \
add $8, %rsp; \
pop %rbx; \ pop %rbx; \
pop %r12; \ pop %r12; \
pop %r13; \ pop %r13; \
@@ -56,6 +57,7 @@ main: \
push %r13; \ push %r13; \
push %r12; \ push %r12; \
push %rbx; \ push %rbx; \
sub $8, %rsp; \
main_after_prologue: \ main_after_prologue: \
; ;