9db2541d4c
This adds a specific unwind plan for AArch64 Linux sigreturn frames. Previously we assumed that the fp would be valid here but it is not. https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/vdso/sigreturn.S On Ubuntu Bionic it happened to point to an old frame info which meant you got what looked like a correct backtrace. On Focal, the info is completely invalid. (probably due to some code shuffling in libc) This adds an UnwindPlan that knows that the sp in a sigreturn frame points to an rt_sigframe from which we can offset to get saved sp and pc values to backtrace correctly. Based on LibUnwind's change: https://reviews.llvm.org/D90898 A new test is added that sets all compares the frames from the initial signal catch to the handler break. Ensuring that the stack/frame pointer, function name and register values match. (this test is AArch64 Linux specific because it's the only one with a specific unwind plan for this situation) Fixes https://bugs.llvm.org/show_bug.cgi?id=52165 Reviewed By: omjavaid, labath Differential Revision: https://reviews.llvm.org/D112069
65 lines
2.4 KiB
C
65 lines
2.4 KiB
C
#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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void handler(int sig) {
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// The kernel only changes a few registers so set them all to something other
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// than the values in sigill() so that we can't fall back to real registers
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// and still pass the test.
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#define SETREG(N) "mov x" N ", #" N "+1\n\t"
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asm volatile(
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/* clang-format off */
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/* x0 is used for a parameter */
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SETREG("1") SETREG("2") SETREG("3")
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SETREG("4") SETREG("5") SETREG("6") SETREG("7")
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SETREG("8") SETREG("9") SETREG("10") SETREG("11")
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SETREG("12") SETREG("13") SETREG("14") SETREG("15")
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SETREG("16") SETREG("17") SETREG("18") SETREG("19")
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SETREG("20") SETREG("21") SETREG("22") SETREG("23")
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SETREG("24") SETREG("25") SETREG("26") SETREG("27")
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SETREG("28") // fp/x29 needed for unwiding
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SETREG("30") // 31 is xzr/sp
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/* clang-format on */
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::
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: /* skipped x0 */ "x1", "x2", "x3", "x4", "x5", "x6", "x7", "x8",
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"x9", "x10", "x11", "x12", "x13", "x14", "x15", "x16", "x17", "x18",
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"x19", "x20", "x21", "x22", "x23", "x24", "x25", "x26", "x27",
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"x28",
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/* skipped fp/x29 */ "x30");
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printf("Set a breakpoint here.\n");
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exit(0);
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}
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static void sigill() {
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// Set all general registers to known values to check
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// that the signal unwind plan sets their locations correctly.
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#define SETREG(N) "mov x" N ", #" N "\n\t"
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asm volatile(
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/* clang-format off */
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SETREG("0") SETREG("1") SETREG("2") SETREG("3")
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SETREG("4") SETREG("5") SETREG("6") SETREG("7")
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SETREG("8") SETREG("9") SETREG("10") SETREG("11")
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SETREG("12") SETREG("13") SETREG("14") SETREG("15")
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SETREG("16") SETREG("17") SETREG("18") SETREG("19")
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SETREG("20") SETREG("21") SETREG("22") SETREG("23")
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SETREG("24") SETREG("25") SETREG("26") SETREG("27")
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SETREG("28") SETREG("29") SETREG("30") /* 31 is xzr/sp */
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/* clang-format on */
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".inst 0x00000000\n\t" // udf #0 (old binutils don't support udf)
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::
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: "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7", "x8", "x9", "x10",
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"x11", "x12", "x13", "x14", "x15", "x16", "x17", "x18", "x19",
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"x20", "x21", "x22", "x23", "x24", "x25", "x26", "x27", "x28",
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"x29", "x30");
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}
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int main() {
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if (signal(SIGILL, handler) == SIG_ERR) {
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perror("signal");
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return 1;
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}
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sigill();
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return 2;
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}
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